# 03 - 333 Gastrointestinal Endoscopy

### 333 Gastrointestinal Endoscopy

for nausea in first-trimester pregnancy. Peppermint oil and caraway 
seed oil products and herbal preparations such as STW 5 (a nineherb mixture) are useful for functional dyspepsia and IBS. Lowpotency pancreatic enzyme preparations are sold as digestive aids 
but have little evidence to support their efficacy.
THERAPIES TARGETING GUT DYSBIOSIS
Antibiotics are prescribed to treat H. pylori–induced ulcers, infec­
tious diarrhea, complicated diverticulitis, and small intestinal 
bacterial overgrowth. Some cases of diarrhea-predominant IBS 
respond to the nonabsorbable antibiotic rifaximin. Probiotics con­
taining bacterial cultures and prebiotics that selectively nourish 
nonnoxious commensal bacteria have been given as adjunctive 
therapy for infectious diarrhea and IBS, with limited evidence of 
efficacy. Postbiotics are metabolites made by probiotic organisms 
that inhibit pathogenic luminal bacteria. Transplanting donor feces 
into the colon by colonoscopy or enema is effective treatment for 
recurrent Clostridioides difficile colitis. Commercial oral and rectal 
microbiota-based products have been approved or are in develop­
ment for this indication.
THERAPEUTIC ENDOSCOPY
In addition to its diagnostic role, endoscopy has numerous thera­
peutic capabilities. Cautery techniques and injection of vasocon­
strictor substances can stop hemorrhage from ulcers and vascular 
malformations. Endoscopically placed clips can occlude arterial 
bleeding sites, while hemostatic powder sprays can stop brisk per­
sistent GI bleeding. Endoscopic encirclement of esophageal varices 
and hemorrhoids with constricting bands stops hemorrhage from 
these sites. Bleeding gastric varices can be injected with thrombin or 
cyanoacrylate. Endoscopy can remove polyps in the stomach, small 
bowel, or colon. Decompressive colonoscopy withdraws excess 
gas in some cases of acute colonic pseudoobstruction. Endoscopic 
mucosal resection, submucosal dissection, and radiofrequency 
techniques ablate some cases of Barrett’s esophagus with dysplasia 
and resect superficial cancers or subepithelial tumors elsewhere in 
the gut. Obstructions of the GI lumen and pancreaticobiliary tree 
are relieved by endoscopic dilation or placing plastic or expandable 
metal stents. Endoscopic sphincterotomy of the ampulla of Vater 
treats choledocholithiasis. Cholangioscopy can facilitate stone lith­
otripsy in the common bile duct, ablation of small ductal tumors, 
and placement of gallbladder stents to facilitate drainage in nonop­
erative candidates. Interventional EUS is used for pancreatic cyst 
gastrostomy using lumen-apposing metal stents, pancreatic necro­
sectomy, and placement of fiducial markers to direct pancreatic and 
rectal radiotherapy. EUS also can facilitate endoscopic access to the 
excluded distal stomach in patients who have undergone bariatric 
gastric bypass surgery using similar stents so that ERCP can be 
done for pancreaticobiliary conditions. EUS-directed stent place­
ment can manage postsurgical stenoses after pancreatic resection. 
Endoscopy is used to insert gastric feeding tubes. Peroral endo­
scopic myotomy is performed on the lower esophageal sphincter 
in achalasia, the pylorus in gastroparesis, and the upper esophageal 
sphincter for Zenker’s diverticulum. Endoscopic treatments for acid 
reflux including transoral incisionless fundoplication have been 
developed as potential alternatives to surgery. Endoscopic bariatric 
methods, including intragastric balloons, sleeve gastroplasty, and 
duodenal resurfacing and diversion, have been devised.

PART 10
Disorders of the Gastrointestinal System
INTERVENTIONAL RADIOLOGY
Interventional radiology techniques offer benefits in selected set­
tings. Angiographic embolization or vasoconstriction decreases 
bleeding from gut sites not amenable to endoscopic intervention. 
Angiographic embolectomy, stent placement, and thrombolysis 
also manage mesenteric ischemia. Dilatation or stenting under 
fluoroscopic guidance relieves luminal strictures. Contrast enemas 
can reduce colon volvulus. CT- and ultrasound-directed drainage of 
abdominal fluid collections can obviate the need for surgery. Per­
cutaneous transhepatic cholangiography relieves biliary obstruction 
when ERCP is contraindicated. Percutaneous cholecystostomy treats 

acute cholecystitis in patients unable to undergo cholecystectomy. 
Transjugular intrahepatic portosystemic shunts are performed for 
variceal hemorrhage not amenable to endoscopic therapy. Litho­
tripsy is rarely performed to fragment gallstones in patients who 
are not surgical candidates. Radiologic approaches are often chosen 
over endoscopy for gastroenterostomy placement. Radiographic 
assistance is sometimes needed for placement of central venous 
catheters for parenteral nutrition.
SURGERY
Roles of surgery in GI conditions include disease cure, symptom 
control, maintenance of nutrition, and palliation of unresectable 
neoplasm. Surgery cures medication-unresponsive ulcerative coli­
tis, diverticulitis, cholecystitis, appendicitis, and intraabdominal 
abscess, but only reduces symptoms and treats complications in 
Crohn’s disease. Surgery is performed for ulcer complications like 
bleeding, obstruction, or perforation and intestinal obstructions 
that persist after conservative care. Gastroesophageal fundoplica­
tion is performed for refractory acid reflux. Acid exposure time 
on pH testing helps select candidates for fundoplication. Achalasia 
responds to operations to reduce lower esophageal sphincter tone. 
Operations for motor disorders include implanted electrical stimu­
lators for gastroparesis and electrical devices and artificial sphinc­
ters for fecal incontinence. Surgery can place a jejunostomy for 
long-term enteral feedings. Other common indications for surgery 
include hernias, hemorrhoids, and nonhealing anal fissures.
PSYCHOLOGICAL APPROACHES AND PHYSICAL THERAPY
Psychological therapies, including psychotherapy, cognitive behav­
ioral therapy, and hypnosis, show efficacy in DGBIs and are most 
beneficial for patients with significant psychological dysfunction. 
Behavioral therapists provide instruction in diaphragmatic breath­
ing for belching or rumination. Biofeedback methods administered 
by physical therapists can treat refractory fecal incontinence or 
constipation secondary to dyssynergia.
■
■FURTHER READING
Benech N et al: Update on microbiota-derived therapies for recurrent 
Clostridioides difficile infections. Clin Microbiol Infect 30:462, 2024.
Gergely M et al: Management of refractory inflammatory bowel 
disease. Curr Opin Gastroenterol 38:347, 2022.
Hossain B et al: Prevalence and impact of gastrointestinal manifesta­
tions in COVID-19 patients: A systematic review. J Community Hosp 
Intern Med Perspect 13:39, 2023.
Jain S et al: Optimal strategies for colorectal cancer screening. Curr 
Treat Options Oncol 23:474, 2022.
Orpen-Palmer J et al: Update on the management of upper gastroin­
testinal bleeding. BMJ Med 1:e000202, 2022.
Shakir SM et al: Updates to the diagnosis and clinical management of 
Helicobacter pylori infections. Clin Chem 69:869, 2023.
Louis Michel Wong Kee Song, Vinay 
Chandrasekhara, Mark Topazian

Gastrointestinal 

Endoscopy
Gastrointestinal endoscopy has been attempted for over 200 years, 
but the introduction of semirigid and flexible gastroscopes in the 
mid-twentieth century marked the dawn of the modern endoscopic 
era. Since then, rapid advances in endoscopic technology have led to

FIGURE 333-1  Gastrointestinal endoscope. Shown here is a conventional 
colonoscope with control knobs for tip deflection, push buttons for suction and 
air insufflation (single arrows), and a working channel for passage of accessories 
(double arrows).
dramatic changes in the diagnosis and treatment of many digestive 
diseases. Innovative endoscopic devices and new endoscopic treatment 
modalities continue to expand the use of endoscopy in patient care.
Flexible endoscopes provide an electronic video image generated 
by a charge-coupled device (CCD) or a complementary metal oxide 
semiconductor (CMOS) chip in the tip of the endoscope. Operator 
controls permit deflection of the endoscope tip; fiberoptic bundles 
or light-emitting diodes provide light at the tip of the endoscope; and 
working channels allow washing, suctioning, and the passage of instru­
ments (Fig. 333-1). Progressive changes in the diameter and stiffness 
of endoscopes have improved the ease and patient tolerance of endos­
copy. High-resolution and high-definition endoscopes equipped with 
electronic and optical magnification capabilities enable acquisition 
of images with a high level of detail. Advanced imaging techniques, 
including narrow-band imaging (Fig. 333-2) and real-time imageprocessing enhancement algorithms, aid in tissue characterization or 
differentiation.
ENDOSCOPIC PROCEDURES
■
■UPPER ENDOSCOPY
Upper gastrointestinal endoscopy, also referred to as esophagogastro­
duodenoscopy (EGD), is performed by passing a flexible endoscope 
through the mouth into the esophagus, stomach, and duodenum. The 
procedure is the best method for examining the upper gastrointestinal 
mucosa (Fig. 333-3). While the upper gastrointestinal radiographic 
series has similar accuracy for diagnosis of duodenal ulcer (Fig. 333-4), 
EGD is superior for detection of gastric ulcers (Fig. 333-5) and flat 
mucosal lesions, such as Barrett’s esophagus (Fig. 333-6), and it per­
mits directed biopsy and endoscopic therapy. Intravenous sedation 
is given to most patients in the United States to ease the anxiety and 
discomfort of the procedure, although in many countries, EGD is rou­
tinely performed with topical pharyngeal anesthesia only. Patient toler­
ance of unsedated EGD is improved by the use of an ultrathin, 5-mm 
diameter endoscope that can be passed transorally or transnasally.
■
■COLONOSCOPY
Colonoscopy is performed by passing a flexible colonoscope through 
the anal canal into the rectum and colon. The cecum is reached in 
>95% of cases, and the terminal ileum (Fig. 333-7) can usually be 
examined. Colonoscopy is the gold standard for imaging the colonic 
mucosa (Fig. 333-8). Colonoscopy has greater sensitivity than barium 
enema for the detection of colitis (Fig. 333-9), colon polyps (Fig. 333-10), 
and colorectal cancer (Fig. 333-11). Computed tomography (CT) colo­
nography rivals the accuracy of colonoscopy for the detection of some 

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Gastrointestinal Endoscopy 
B
FIGURE 333-2  Flat colon polyp. A. White-light imaging. B. Corresponding narrowband imaging enhances mucosal features and lesion delineation.
polyps and cancer, although it is not as sensitive for the detection of flat 
lesions, such as serrated polyps (Fig. 333-12). Intravenous sedation is 
usually given before colonoscopy in the United States, although a will­
ing patient and a skilled examiner can complete the procedure without 
sedation in many cases.
■
■FLEXIBLE SIGMOIDOSCOPY
Flexible sigmoidoscopy is akin to colonoscopy, but it visualizes only the 
rectum and a variable portion of the left colon, typically to 60 cm from 
the anal verge. This procedure may result in abdominal cramping and 
discomfort, but it is brief and thus can be performed without sedation. 
Flexible sigmoidoscopy is primarily used for evaluation of diarrhea and 
rectal outlet bleeding.
■
■SMALL-BOWEL ENDOSCOPY
Three endoscopic techniques are currently used to evaluate the small 
intestine, most often in patients presenting with presumed smallbowel bleeding. For capsule endoscopy, the patient swallows a dispos­
able capsule that contains a CMOS chip camera. Color still images 
(Fig. 333-13) are transmitted wirelessly to an external receiver at sev­
eral frames per second until the capsule’s battery is exhausted or it is 
passed into the toilet. Capsule endoscopy enables visualization of the 
small-bowel mucosa beyond the reach of a conventional endoscope,

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PART 10
Disorders of the Gastrointestinal System
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E
FIGURE 333-3  Normal upper endoscopic examination. A. Esophagus. B. Gastroesophageal junction. C. Gastric fundus. D. Gastric body. E. Gastric antrum. F. Pylorus. 
G. Duodenal bulb. H. Second portion of the duodenum.

B
D
F

G
FIGURE 333-3  (Continued)
A
FIGURE 333-4  Duodenal ulcers. A. Ulcer with a small, flat, pigmented spot in its base. B. Ulcer with a visible vessel (arrow) in a patient with recent hemorrhage.
A
FIGURE 333-5  Gastric ulcers. A. Benign gastric ulcer in the antrum. B. Malignant gastric ulcer involving greater curvature of stomach.

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B

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FIGURE 333-6  Barrett’s esophagus. A. Salmon-colored Barrett’s mucosa extending proximally from the gastroesophageal junction. B. Barrett’s esophagus with a suspicious 
nodule (arrow) identified during endoscopic surveillance. C. Histologic finding of intramucosal adenocarcinoma in the endoscopically resected nodule. Tumor extends into 
the esophageal submucosa (arrow). D. Barrett’s esophagus with locally advanced adenocarcinoma.
PART 10
Disorders of the Gastrointestinal System
and at present, it is solely a diagnostic procedure. Patients with a 
history of prior intestinal surgery or Crohn’s disease are at risk for 
capsule retention at the site of a clinically unsuspected small-bowel 
stricture, and ingestion of a “patency capsule” composed of radiologi­
cally opaque biodegradable material may be indicated before capsule 
endoscopy in such patients.
Push enteroscopy is generally performed using a variable-stiffness 
pediatric or adult colonoscope, or a dedicated enteroscope with or 
without the assistance of a stiffening overtube that extends from the 
mouth to the small intestine. The proximal to mid-jejunum is usu­
ally reached, and the instrument channel of the endoscope allows for 
biopsy or endoscopic therapy.
A
FIGURE 333-7  Colonoscopic view of terminal ileum. A. Normal-appearing terminal ileum (TI). B. View of normal villi of TI enhanced by examination under water immersion.

B
D
Deeper intubation of the small bowel can be accomplished by single- 
or double-balloon enteroscopy, which enables pleating of the small 
intestine onto an overtube (Fig. 333-14, Video V5-1). With balloonassisted enteroscopy, the entire small intestine can be visualized in 
some patients when both the oral and anal routes of insertion are used. 
Biopsies and endoscopic therapy, such as thermal ablation of vascular 
ectasias and polypectomy, can be performed throughout the visualized 
small bowel (Fig. 333-15).
■
■ENDOSCOPIC RETROGRADE 
CHOLANGIOPANCREATOGRAPHY
During endoscopic retrograde cholangiopancreatography (ERCP), a 
side-viewing endoscope is passed through the mouth to the duodenum, 
B

A
C
FIGURE 333-8  Normal colonoscopic examination. A. Cecum with view of appendiceal orifice. B. Ileocecal valve. C. Normal-appearing colon. D. Rectum (retroflexed view).
the bile duct and/or pancreatic duct is cannulated with a thin plastic 
catheter, and radiographic contrast material is injected under fluo­
roscopic guidance (Fig. 333-16). When indicated, the major papilla 
can be incised using the technique of endoscopic sphincterotomy 
(Fig. 333-17). Stones can be retrieved from the ducts, biopsies can be 
performed, strictures can be dilated and/or stented (Fig. 333-18), and 
ductal leaks can be treated (Fig. 333-19). ERCP is usually performed 
for therapy but is also important diagnostically as it facilitates tissue 
sampling of biliary or pancreatic ductal strictures.
■
■ENDOSCOPIC ULTRASOUND
Endoscopic ultrasound (EUS) utilizes ultrasound transducers incor­
porated into the tip of a flexible endoscope. Ultrasound images are 
obtained of the gut wall and adjacent organs, vessels, lymph nodes, and 
other structures. High-resolution images are obtained by bringing a 
high-frequency ultrasound transducer close to the area of interest via 
endoscopy. EUS provides the most accurate preoperative local stag­
ing of esophageal, pancreatic, and rectal malignancies (Fig. 333-20), 
but it does not detect distant metastases that are beyond its imaging 
range. EUS is also useful for diagnosis of bile duct stones, gallbladder 
disease, subepithelial gastrointestinal lesions, and chronic pancreatitis. 
Fine-needle aspirates and core biopsies of organs, masses, and lymph 
nodes in the posterior mediastinum, abdomen, retroperitoneum, and 

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D
pelvis can be obtained under EUS guidance (Fig. 333-21). EUS-guided 
therapeutic procedures are increasingly performed, including drainage 
of abscesses, pseudocysts, and pancreatic necrosis into the gut lumen 
(Video V5-2); celiac plexus neurolysis for treatment of pancreatic 
pain; ethanol ablation of pancreatic neuroendocrine tumors; treatment 
of gastric and intestinal varices; biliary or pancreatic drainage; and 
endoscopic gastrojejunostomy for palliation of malignant gastric outlet 
obstruction (Video V5-3).
■
■NATURAL ORIFICE TRANSLUMINAL 
ENDOSCOPIC SURGERY
Natural orifice transluminal endoscopic surgery (NOTES) represents a 
collection of endoscopic methods that entail passage of an endoscope 
or its accessories into or through the wall of the gastrointestinal tract 
to perform diagnostic or therapeutic interventions. Some NOTES 
procedures, such as percutaneous endoscopic gastrostomy (PEG) or 
endoscopic necrosectomy of pancreatic necrosis, are well-established 
clinical procedures (Video V5-2); others such as peroral endoscopic 
myotomy (POEM) for achalasia (Fig. 333-22) and gastroparesis, 
peroral endoscopic tumorectomy (POET) (Fig. 333-23), and endo­
scopic full-thickness resection (EFTR) of gastrointestinal mural lesions 
(Fig. 333-24, Video V5-4), are newer minimally invasive therapeutic 
options.

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PART 10
Disorders of the Gastrointestinal System
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FIGURE 333-9  Causes of colitis. A. Chronic ulcerative colitis with diffuse inflammation. B. Severe Crohn’s colitis with deep ulcers. C. Pseudomembranous colitis with yellow, 
adherent pseudomembranes. D. Ischemic colitis with patchy mucosal edema, subepithelial hemorrhage, superficial ulcerations, and cyanosis.
A
FIGURE 333-10  Colonic polyps. A. Pedunculated polyp on a stalk. B. Sessile polyp.

B
D
B

FIGURE 333-11  Ulcerated colon adenocarcinoma narrowing the colonic lumen.
A
B
C
FIGURE 333-12  Flat serrated polyp in the cecum. A. Appearance of the lesion under 
conventional white-light imaging. B. Mucosal patterns and boundary of the lesion 
enhanced with narrow-band imaging. C. Submucosal lifting of the lesion with dye 
(methylene blue) injection before resection.

FIGURE 333-13  Capsule endoscopy. Image of a jejunal vascular ectasia.
■
■ENDOSCOPIC RESECTION AND CLOSURE 
TECHNIQUES
Endoscopic mucosal resection (EMR) (Fig. 333-25, Video V5-5) and 
endoscopic submucosal dissection (ESD) (Fig. 333-26, Video V5-6) 
are the two commonly used techniques for the resection of benign and 
early-stage malignant gastrointestinal neoplasms. In addition to pro­
viding larger specimens for more accurate histopathologic assessment 
and diagnosis, these techniques may be curative for some dysplastic 
lesions and superficial carcinomas involving the esophagus, stomach, 
and colon.
CHAPTER 333
Gastrointestinal Endoscopy 
Several devices are available for closure of mucosal defects created 
by EMR and ESD, as well as gastrointestinal fistulas and perfora­
tions. Endoscopic clips deployed through the working channel of an 
FIGURE 333-14  Double-balloon enteroscopy. Radiograph of the orally inserted 
instrument deep in the small intestine.

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PART 10
Disorders of the Gastrointestinal System
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C
FIGURE 333-15  Nonsteroidal anti-inflammatory drug (NSAID)–induced proximal 
ileal stricture managed via double-balloon enteroscopy. A. High-grade ileal 
stricture causing obstructive symptoms. B. Balloon dilation of the ileal stricture. 
C. Appearance of the stricture after dilation.

A
B
FIGURE 333-16  Endoscopic retrograde cholangiopancreatography (ERCP) for bile 
duct stones. A. Faceted bile duct stones are demonstrated in the common bile duct 
and common hepatic duct. B. After endoscopic sphincterotomy, the stones are 
extracted with a stone extraction balloon.

A
C
FIGURE 333-17  Endoscopic sphincterotomy. A. A normal-appearing ampulla of Vater (arrow). B. Biliary endoscopic sphincterotomy is performed with electrosurgery. C. Bile 
duct stones are extracted with a balloon catheter.
endoscope have been used for many years to treat bleeding lesions, 
and the development of larger over-the-scope clips has facilitated 
endoscopic closure of gastrointestinal fistulas and perforations not 
previously amenable to endoscopic therapy (Video V5-7). Endoscopic 
suturing can be used to close some perforations and large defects (Fig. 
333-27), anastomotic leaks, and fistulas. Endoscopic suturing may also 
be used to prevent stent migration (Fig. 333-28, Video V5-8) and to 
perform endoscopic bariatric procedures. These technologies are play­
ing an expanding role in patient care.
RISKS OF ENDOSCOPY
Medications used during sedation may cause respiratory depression or 
allergic reactions. All endoscopic procedures carry some risk of bleed­
ing and gastrointestinal perforation. The risk is small with diagnostic 

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Gastrointestinal Endoscopy 
upper endoscopy, flexible sigmoidoscopy, and colonoscopy (<1:1000 
procedures), but it ranges from 0.5 to 5% when therapeutic maneuvers 
such as polypectomy, EMR, ESD, control of hemorrhage, or stricture 
dilation are performed. The risk of adverse events for diagnostic EUS 
(without needle aspiration) is similar to that for diagnostic upper 
endoscopy.
Infectious complications are uncommon with most endoscopic 
procedures. Some procedures carry a higher incidence of postproce­
dural bacteremia, and prophylactic antibiotics may be indicated (Table 
333-1). Management of antithrombotic agents before endoscopic pro­
cedures should take into account the procedural risk of hemorrhage, 
the agent, and the patient condition, as summarized in Table 333-2.
ERCP carries additional risks. Pancreatitis occurs in ~5% of patients 
undergoing the procedure, and young, anicteric patients with normal

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PART 10
Disorders of the Gastrointestinal System
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FIGURE 333-18  Endoscopic diagnosis, staging, and palliation of hilar cholangiocarcinoma. A. Endoscopic retrograde cholangiopancreatography (ERCP) in a patient with 
obstructive jaundice demonstrates a malignant-appearing stricture of the biliary confluence extending into the left and right intrahepatic ducts. B. Per oral cholangioscopy 
demonstrating a stricture with dilated, tortuous vessels with a malignant appearance. C. Intraductal biopsy obtained during ERCP demonstrates malignant cells infiltrating 
the submucosa of the bile duct wall (arrow). (Image courtesy of Dr. Thomas Smyrk.) D. Endoscopic placement of multiple plastic stents draining the right anterior, right 
posterior, and left systems relieves the biliary obstruction. 
ducts are at increased risk (up to 25%). Post-ERCP pancreatitis is 
usually mild and self-limited, but it may result in prolonged hospital­
ization, surgery, diabetes, or death when severe. Significant bleeding 
occurs after endoscopic sphincterotomy in ~1% of cases. Ascending 
cholangitis, pseudocyst infection, duodenal perforation, and abscess 
formation may occur as a result of ERCP.
PEG tube placement during EGD is associated with a 10–15% inci­
dence of adverse events, most often wound infections. Fasciitis, pneu­
monia, bleeding (Fig. 333-29), buried bumper syndrome (Fig. 
333-30), and colonic injury may result from PEG tube placement.

B
D
URGENT ENDOSCOPY
■
■ACUTE GASTROINTESTINAL HEMORRHAGE
Endoscopy is the primary diagnostic and therapeutic procedure for 
patients with acute gastrointestinal hemorrhage. Although gastroin­
testinal bleeding stops spontaneously in most cases, some patients will 
have persistent or recurrent hemorrhage that may be life-threatening. 
Clinical predictors of rebleeding help identify patients most likely to 
benefit from urgent endoscopy and endoscopic, angiographic, or surgi­
cal hemostasis.

A
FIGURE 333-19  Bile leak. A. Site of leak (arrow) from the cystic duct after laparoscopic cholecystectomy. B. Contrast leaks from the cystic duct stump across surgical clips 
into the gallbladder fossa (arrow).
A
FIGURE 333-20  Local staging of gastrointestinal cancers with endoscopic ultrasound. In each example, the arrowhead marks the primary tumor and the arrow indicates 
the muscularis propria (MP) of the intestinal wall. A. T2 gastric cancer. The tumor invades the MP. B. Submucosal gastric tumor. The tumor is confined to the submucosal 
space without invasion into the MP.
A
FIGURE 333-21  Endoscopic ultrasound (EUS)–guided tissue sampling. A. Ultrasound image of a 22-gauge needle (arrow) passed through the gastric wall and positioned in 
a hypoechoic pancreatic neck mass. B. Touch preparation demonstrating aspirated malignant cells.

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Gastrointestinal Endoscopy 
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B

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PART 10
Disorders of the Gastrointestinal System
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G
FIGURE 333-22  Peroral endoscopic myotomy (POEM) for achalasia. A. Dilated aperistaltic esophagus with retained secretions. B. Hypertonic lower esophageal sphincter 
(LES) region. C. Mucosal incision (mucosotomy) 10 cm proximal to the LES. D. Submucosal dissection using an electrosurgical knife following endoscope entry through the 
mucosotomy site into the submucosal space. E. Completion of submucosal tunnel to the cardia. F. Initiation of myotomy of the muscularis propria distal to the mucosotomy 
site. G. Completion of myotomy to the cardia. H. Closure of mucosotomy site with clips. I. Patulous gastroesophageal junction following myotomy.
Initial Evaluation 
The initial evaluation of the bleeding patient 
focuses on the severity of hemorrhage as reflected by the presence of 
supine hypotension or tachycardia, postural vital sign changes, and 
the frequency of hematemesis or melena. Decreases in hematocrit and 
hemoglobin lag behind the clinical course and are not reliable gauges 
of the magnitude of acute bleeding. Nasogastric tube aspiration and 
lavage can also be used to judge the severity of bleeding, but these are 
no longer routinely performed for this purpose. The bedside initial 
evaluation, completed well before the bleeding source is confidently 
identified, guides immediate supportive care of the patient; triage to 
outpatient follow-up, a hospital ward, or an intensive care unit; and 
timing of endoscopy. The severity of the initial hemorrhage is the most 
important indication for urgent endoscopy, since a large initial bleed 
increases the likelihood of ongoing or recurrent bleeding. Patients 
with resting hypotension or orthostatic change in vital signs, repeated 
hematemesis, bloody nasogastric aspirate that does not clear with 
large-volume lavage, or those requiring blood transfusions should be 
considered for urgent endoscopy within 12–24 h of presentation. In 
addition, patients with cirrhosis, coagulopathy, or respiratory or renal 
failure and those >70 years old are more likely to have significant 
rebleeding and to benefit from prompt evaluation and treatment.

C
F
I
Bedside evaluation also suggests an upper or lower gastrointestinal 
source of bleeding in most patients. Over 90% of patients with melena 
are bleeding proximal to the ligament of Treitz, and ~85% of patients 
with hematochezia are bleeding from the colon. Melena can result from 
bleeding in the small bowel or right colon, especially in older patients 
with slow colonic transit. Conversely, some patients with massive 
hematochezia may be bleeding from an upper gastrointestinal source, 
with rapid intestinal transit. An urgent upper endoscopy should be 
considered in such patients.
Endoscopy should be performed after the patient has been resus­
citated with intravenous fluids and transfusions, as necessary. Marked 
coagulopathy or thrombocytopenia is usually treated before endoscopy, 
since correction of these abnormalities may lead to resolution of bleed­
ing, and techniques for endoscopic hemostasis are limited in such 
patients. Metabolic derangements should also be addressed. Tracheal 
intubation for airway protection should be considered before upper 
endoscopy in patients with repeated recent hematemesis, particularly in 
those with suspected variceal hemorrhage. A single dose of erythromy­
cin (3–4 mg/kg or 250 mg) administered intravenously 30–90 min before 
upper endoscopy increases gastric emptying and may clear blood and 
clots from the stomach to improve endoscopic visualization.

A
C
E
G
FIGURE 333-23  Peroral endoscopic tumorectomy (POET). A. Mid-esophageal subepithelial lesion (arrow). B. Mucosal incision (mucosotomy) 5 cm proximal to the 
lesion. C. Submucosal dissection and tunneling to the site of the lesion. D. Dissection of the lesion from its attachment to the muscularis propria. E. Postresection defect 
through the muscularis propria. F. Mucosotomy site. G. Closure of mucosotomy site with clips. H. Resected specimen (leiomyoma).

B
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Gastrointestinal Endoscopy 
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H

A
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PART 10
Disorders of the Gastrointestinal System
FIGURE 333-24  Endoscopic full-thickness resection (EFTR) of a gastrointestinal stromal tumor. A. Subepithelial lesion in the proximal stomach. B. Hypoechoic lesion arising 
from the fourth layer (muscularis propria) at endoscopic ultrasound. C. Full-thickness resection defect. D. Closure of defect using an over-the-scope clip.
Most patients with hematochezia who are otherwise stable can 
undergo semi-elective colonoscopy. Controlled trials have not shown a 
benefit to urgent colonoscopy (within 24 h of presentation) in patients 
hospitalized with hematochezia, although selected patients with mas­
sive or recurrent large-volume episodes of hematochezia should prob­
ably undergo urgent colonoscopy after both upper endoscopy and a 
rapid colonic purge with an oral polyethylene glycol solution. Colo­
noscopy has a higher diagnostic yield than radionuclide bleeding scans 
or catheter-based angiography in lower gastrointestinal bleeding, and 
endoscopic therapy can be applied in some cases. Urgent colonoscopy 
A
FIGURE 333-25  Endoscopic mucosal resection (EMR). A. Large sessile polypoid fold in the transverse colon. B. Lifting of lesion following submucosal fluid injection. 
C. Piecemeal hot snare resection. D. Initial resection site. E. Resection defect following completion of piecemeal EMR.

B
can be hindered by poor visualization due to persistent vigorous bleed­
ing with recurrent hemodynamic instability, and other techniques (e.g., 
angiography or even emergent subtotal colectomy) must be employed. 
The anal and rectal mucosa should also be visualized endoscopically 
early in the course of massive rectal bleeding, as bleeding lesions in or 
close to the anal canal may be identified that are amenable to endo­
scopic or surgical transanal hemostatic techniques.
Peptic Ulcer 
The endoscopic appearance of peptic ulcers provides 
useful prognostic information and guides the need for endoscopic 
B

C
E
FIGURE 333-25  (Continued)
A
FIGURE 333-26  Endoscopic submucosal dissection (ESD). A. Large, flat, distal rectal adenoma. B. Circumferential incision following submucosal fluid injection at the 
periphery of the lesion. C. ESD using an electrosurgical knife. D. Rectal defect following ESD. E. Specimen resected en bloc.

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Gastrointestinal Endoscopy 
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PART 10
Disorders of the Gastrointestinal System
FIGURE 333-27  Closure of large defect using an endoscopic suturing device. A. Ulcerated inflammatory fibroid polyp in the antrum. B. Large defect following endoscopic 
submucosal dissection of the lesion. C. Closure of the defect using endoscopic sutures (arrows). D. Resected specimen.
C
D
E
A
B
FIGURE 333-26  (Continued)

C
FIGURE 333-27  (Continued)
therapy in patients with acute hemorrhage (Fig. 333-31). A cleanbased ulcer is associated with a low risk (3–5%) of rebleeding; patients 
with melena and a clean-based ulcer may be discharged home from 
the emergency room or endoscopy suite if they are young, reliable, 
otherwise healthy, and able to return as needed. Flat pigmented spots 
and adherent clots covering the ulcer base have a 10% and 20% risk of 
rebleeding, respectively. Flat pigmented spots do not require treatment, 
but endoscopic therapy is often applied to an ulcer with an adherent 
clot. When a fibrin plug is seen protruding from a vessel wall in the 
base of an ulcer (so-called sentinel clot or visible vessel), the risk of 
rebleeding from the ulcer approximates 40%. This finding typically 
leads to endoscopic therapy to decrease the rebleeding rate. When 
A
C
FIGURE 333-28  Prevention of stent migration using endoscopic sutures. A. Esophagogastric anastomotic stricture refractory to balloon dilation. B. Temporary placement of 
a covered esophageal stent. C. Endoscopic suturing device to anchor the stent to the esophageal wall. D. Stent fixation with endoscopic sutures (arrows).

D
active spurting from an ulcer is seen, there is a 90% risk of ongoing 
bleeding without endoscopic or surgical therapy.
Endoscopic therapy of ulcers with high-risk stigmata typically 
lowers the rebleeding rate to 5–10%. Several hemostatic techniques 
are available, including injection of epinephrine or a sclerosant into 
and around the vessel (Fig. 333-32), “coaptive coagulation” of the 
vessel in the base of the ulcer using a thermal probe that is pressed 
against the site of bleeding (Fig. 333-33), placement of through-thescope clips (Fig. 333-34) or an over-the-scope clip (Fig. 333-35), 
application of a hemostatic powder or gel, or a combination of these 
modalities (Video V5-9). Epinephrine injection can slow or stop 
active bleeding, but it is not a stand-alone technique for definitive 
CHAPTER 333
Gastrointestinal Endoscopy 
B
D

TABLE 333-1  Antibiotic Prophylaxis for Endoscopic Procedures
PATIENT CONDITION
PROCEDURE CONTEMPLATED
GOAL OF PROPHYLAXIS
All cardiac conditions
Any endoscopic procedure
Prevention of infective endocarditis
Not recommended
Bile duct obstruction in the absence of 
cholangitis
ERCP with complete drainage
Prevention of cholangitis
Not recommended
Bile duct obstruction in the absence of 
cholangitis
ERCP with anticipated incomplete 
drainage (e.g., sclerosing cholangitis, 
hilar strictures)
Sterile pancreatic fluid collection (e.g., 
pseudocyst, necrosis), which communicates 
with pancreatic duct
ERCP
Prevention of cyst infection
Recommended; continue antibiotics 
after the procedure
Sterile pancreatic fluid collection
Transmural drainage
Prevention of cyst infection
Recommended
Solid lesion along upper GI tract
EUS-FNA or FNB
Prevention of local infection
Not recommendeda
Solid lesion along lower GI tract
EUS-FNA or FNB
Prevention of local infection
Not recommendeda
Cystic lesions along GI tract (including 
mediastinum and pancreas)
EUS-FNA or FNB
Prevention of cyst infection
Recommended
All patients
Percutaneous endoscopic feeding tube 
placement
Cirrhosis with acute GI bleeding
Recommended for all such patients, 
regardless of endoscopic procedures
Continuous peritoneal dialysis
Lower GI tract endoscopy
Prevention of bacterial peritonitis
Recommended
Synthetic vascular graft and other 
nonvalvular cardiovascular devices
Any endoscopic procedure
Prevention of graft and device infection
Not recommendedd
Prosthetic joints
Any endoscopic procedure
Prevention of septic arthritis
Not recommendedd
aLow rates of bacteremia and local infection. bCefazolin or an antibiotic with equivalent coverage of oral and skin flora. cRisk for bacterial infection associated with cirrhosis 
and GI bleeding is well established; ceftriaxone or a quinolone antibiotic recommended. dVery low risk of infection.
Abbreviations: ERCP, endoscopic retrograde cholangiopancreatography; EUS-FNA, endoscopic ultrasound–fine-needle aspiration; EUS-FNB, endoscopic ultrasound–fine 
needle biopsy; GI, gastrointestinal.
Source: Reproduced with permission from MA Kashab et al: Antibiotic prophylaxis for GI endoscopy. Gastrointest Endosc 81:81, 2015.
PART 10
Disorders of the Gastrointestinal System
hemostasis. In conjunction with endoscopic therapy, the administra­
tion of a proton pump inhibitor decreases the risk of rebleeding and 
improves patient outcome.
Varices 
Two complementary strategies guide therapy of bleeding 
varices: local treatment of the bleeding varices and treatment of the 
underlying portal hypertension. Local therapies, including endoscopic 
variceal band ligation, endoscopic variceal sclerotherapy, stent place­
ment, and tamponade with a stent or Sengstaken-Blakemore tube, 
effectively control acute hemorrhage in most patients, although thera­
pies that decrease portal pressure (pharmacologic treatment, surgical 
shunts, or radiologically placed transjugular intrahepatic portosys­
temic shunts) also play an important role.
Endoscopic variceal ligation (EVL) is indicated for the prevention 
of a first bleed (primary prophylaxis) from large esophageal varices 
(Fig. 333-36), particularly in patients in whom nonselective beta 
blockers are contraindicated or not tolerated. EVL is also the preferred 
endoscopic therapy for control of active esophageal variceal bleeding 
and for subsequent eradication of esophageal varices (secondary pro­
phylaxis). During EVL, a varix is suctioned into a cap fitted at the tip 
of the endoscope, and a rubber band is released from the cap, ligating 
the varix (Fig. 333-37, Video V5-10). EVL controls acute hemorrhage 
in up to 90% of patients. Complications of EVL, such as postligation 
ulcer bleeding and esophageal stenosis, are uncommon. Endoscopic 
variceal sclerotherapy (EVS) involves the injection of a sclerosing, 
thrombogenic solution into or next to esophageal varices. EVS also 
controls acute hemorrhage in most patients, but due to its higher 
complication rate, it is generally used as salvage therapy when band 
ligation fails. Bleeding from large gastric fundal varices (Fig. 333-38) 
is best treated with endoscopic cyanoacrylate (“glue”) injection (Video 
V5-11) or EUS-guided coil placement and cyanoacrylate injection, 
since EVL or EVS of these varices is associated with a high rebleeding 
rate. Complications of cyanoacrylate injection include infection and 
glue embolization to other organs, such as the lungs, brain, and spleen.
After treatment of the acute hemorrhage, an elective course of 
endoscopic therapy can be undertaken with the goal of eradicating 

PERIPROCEDURAL ANTIBIOTIC 
PROPHYLAXIS
Prevention of cholangitis
Recommended; continue antibiotics 
after the procedure
Prevention of peristomal infection
Recommendedb
Prevention of infectious complications 
and reduction of mortality
Recommended, upon admissionc
esophageal varices and preventing rebleeding months to years later. 
However, this chronic therapy is less successful, preventing long-term 
rebleeding in ~50% of patients. Pharmacologic therapies that decrease 
portal pressure have similar efficacy. The preferred strategy, however, 
for secondary prophylaxis of variceal bleeding is the combination of 
EVL with a nonselective beta blocker.
Dieulafoy’s Lesion 
This lesion, also called persistent caliber 
artery, is a large-caliber arteriole that runs immediately beneath the 
gastrointestinal epithelium and bleeds through a focal mucosal ero­
sion (Fig. 333-39). Dieulafoy’s lesion commonly involves the lesser 
curvature of the proximal stomach, causes impressive arterial hemor­
rhage, and may be difficult to diagnose when not actively bleeding; it is 
often recognized only after repeated endoscopy for recurrent bleeding. 
Endoscopic therapy, such as thermal coagulation, band ligation, clip 
placement, or endoscopic suturing, is typically effective for control 
of bleeding and sealing of the underlying vessel once the lesion has 
been identified (Video V5-12). Rescue therapies, such as angiographic 
embolization or surgical oversewing, are considered in situations 
where endoscopic therapy has failed.
Mallory-Weiss Tear 
A Mallory-Weiss tear is a linear mucosal rent 
near or across the gastroesophageal junction that is often associated 
with retching or vomiting (Fig. 333-40). When the tear disrupts a 
submucosal arteriole, brisk hemorrhage may result. Endoscopy is the 
best method for diagnosis, and an actively bleeding tear can be treated 
endoscopically with coaptive coagulation, band ligation, or clip place­
ment, with or without epinephrine injection (Video V5-13). Unlike 
peptic ulcer, a Mallory-Weiss tear with a nonbleeding sentinel clot in its 
base rarely rebleeds and thus does not necessitate endoscopic therapy.
Vascular Ectasias 
Vascular ectasias are flat mucosal vascular 
anomalies that are best diagnosed by endoscopy. They usually cause 
slow intestinal blood loss and occur either in a sporadic fashion or in a 
well-defined pattern of distribution (e.g., gastric antral vascular ectasia 
[GAVE] or “watermelon stomach”) (Fig. 333-41). Cecal vascular ecta­
sias, GAVE, and radiation-induced rectal ectasias are often responsive

TABLE 333-2  Management of Antithrombotic Drugs Prior to Endoscopic Procedures
BLEEDING RISK 
OF PROCEDURE
MANAGEMENT
DRUG
Warfarin
Lowa
Continue
N/A
Ensure that INR is not supratherapeutic
 
Highb
Discontinue
3–7 days (usually 5), INR should 
be ≤1.5 for procedure
Dabigatran, rivaroxaban, 
apixaban, edoxaban
Lowa
Hold morning dose on 
day of procedure
Dabigatran
Highb
Discontinue
2–3 days if GFR is ≥50 mL/min, 
4–5 days if GFR is 30–49 mL/min
Rivaroxaban, apixaban, 
edoxaban
Higha
Discontinue
2 days if GFR is ≥60 mL/min, 3 
days if GFR is 30–59 mL/min, 4 
days if GFR is <30 mL/min
Heparin
Lowa
Continue
N/A
 
 
Highb
Discontinue
4–6 h for unfractionated heparin Skip one dose if using low-molecular-weight heparin
Aspirin
Any
Continue
N/A
Low-dose aspirin does not substantially increase the risk 
of endoscopic procedures
Aspirin with dipyridamole
Lowa
Continue
N/A
 
 
Highb
Discontinue
2–7 days
Consider continuing aspirin monotherapy
P2Y12 receptor antagonists 
(clopidogrel, prasugrel, 
ticlopidine, ticagrelor, 
cangrelor)
Lowa
Continue
Coronary stent in place: 
discuss with cardiologist
No coronary stent: 
discontinue, consider 
substituting aspirin
Highb
aLow-risk endoscopic procedures include esophagogastroduodenoscopy (EGD) or colonoscopy with or without biopsy, endoscopic ultrasound (EUS) without fine-needle 
aspiration (FNA), and endoscopic retrograde cholangiopancreatography (ERCP) with stent exchange. bHigh-risk endoscopic procedures include EGD or colonoscopy with 
dilation, polypectomy, or thermal ablation; percutaneous endoscopic gastrostomy (PEG); EUS with FNA; and ERCP with sphincterotomy or pseudocyst drainage. cBridging 
therapy with low-molecular-weight heparin should be considered for patients discontinuing warfarin who are at high risk for thromboembolism, including those with 
(1) prosthetic metal heart valve, (2) atrial fibrillation with a CHA2DS2-VASc score ≥3, mitral stenosis, prosthetic valve or history of stroke or transient ischemic attack; (3) 
mechanical mitral valve; (4) mechanical aortic valve with other thromboembolic risk factors or older-generation mechanical aortic valve; or (5) venous thromboembolism 
(VTE) within the past 3 months.
Abbreviations: GFR, glomerular filtration rate; GI, gastrointestinal; INR, international normalized ratio; N/A, not applicable.
Source: Adapted from RD Acosta et al: Gastrointest Endosc 83:3, 2016; and AM Veitch et al: Gut 70:1611, 2021.
A
FIGURE 333-29  Bleeding from percutaneous endoscopic gastrostomy (PEG) tube placement. A. Patient with melena from a recently placed PEG tube. B. Loosening of the 
internal disk bumper of the PEG tube revealed active bleeding from within the PEG tract.

INTERVAL BETWEEN LAST 
DOSE AND PROCEDURE
COMMENTS
Consider bridging therapy with low-molecular-weight 
heparin for patients at high risk of thrombosisc; usually 
safe to resume warfarin on the same or next day
For life-threatening GI hemorrhage, consider reversal 
with unactivated prothrombin complex concentrate
N/A
 
Bridging therapy not recommended; resume drug when 
bleeding risk is low
For life-threatening GI hemorrhage, consider use of a 
reversal agent
Bridging therapy not recommended; resume drug when 
bleeding risk is low
For life-threatening GI hemorrhage, consider use of a 
reversal agent
N/A
5 days (clopidogrel or 
ticagrelor), 7 days (prasugrel), 
10–14 days (ticlopidine)
Risk of stent thrombosis for at least 12 months after 
insertion of drug-eluting coronary stent or 1 month after 
insertion of bare metal coronary stent
CHAPTER 333
Gastrointestinal Endoscopy 
B

A
FIGURE 333-30  Buried bumper syndrome. A. Migration of the internal disk bumper of a percutaneous endoscopic gastrostomy (PEG) tube through the gastric wall. 
B. Close-up view of the disk bumper (arrow) buried in the gastric wall.
to local endoscopic ablative therapy, such as argon plasma coagulation 
(Video V5-14). Patients with diffuse small-bowel vascular ectasias 
(associated with chronic renal failure and with hereditary hemorrhagic 
telangiectasia) may continue to bleed despite endoscopic treatment 
of easily accessible lesions by conventional endoscopy. These patients 
may benefit from deep enteroscopy with endoscopic hemostasis, or 
pharmacologic therapy, such as octreotide or low-dose thalidomide, in 
those who continue to bleed despite endoscopic therapy.
PART 10
Disorders of the Gastrointestinal System
Colonic Diverticula 
Diverticula form where nutrient arteries 
penetrate the muscular wall of the colon en route to the colonic mucosa 
(Fig. 333-42). The artery found in the base of a diverticulum may 
bleed, causing painless and impressive hematochezia. Colonoscopy 
is indicated in patients with hematochezia and suspected diverticular 
hemorrhage, since other causes of bleeding (e.g., vascular ectasias, 
colitis, and colon cancer) must be excluded. In addition, an actively 
A
FIGURE 333-31  Stigmata of hemorrhage in peptic ulcers. A. Gastric antral ulcer with a clean base. B. Duodenal ulcer with flat pigmented spots (arrows). C. Duodenal ulcer 
with a dense adherent clot. D. Duodenal ulcer with a pigmented protuberance/visible vessel (arrow). E. Duodenal ulcer with active spurting (arrow).

B
bleeding diverticulum may be seen and treated during colonoscopy 
(Fig. 333-43, Video V5-15).
■
■GASTROINTESTINAL OBSTRUCTION AND 
PSEUDOOBSTRUCTION
Endoscopy is useful for evaluation and treatment of some forms of 
gastrointestinal obstruction. An important exception is small-bowel 
obstruction due to surgical adhesions, which is generally not diagnosed 
or treated endoscopically. Esophageal, gastroduodenal, and colonic 
obstruction or pseudoobstruction can all be diagnosed and often man­
aged endoscopically.
Acute Esophageal Obstruction 
Esophageal obstruction by 
impacted food (Fig. 333-44) or an ingested foreign body (Fig. 333-45) is 
a potentially life-threatening event and represents an endoscopic emer­
gency. Left untreated, the patient may develop esophageal ulceration, 
B

C
D
E
FIGURE 333-31  (Continued)
FIGURE 333-32  Injection therapy for ulcer hemostasis. Epinephrine injection into a 
duodenal ulcer with visible vessel (arrow) and adherent clot.

CHAPTER 333
Gastrointestinal Endoscopy 
ischemia, and perforation. Patients with persistent esophageal obstruc­
tion often have hypersalivation and are usually unable to swallow 
water. Sips of a carbonated beverage, sublingual nifedipine or nitrates, 
or intravenous glucagon may resolve an esophageal food impaction, 
but in many patients, an underlying web, ring, or stricture is present, 
and endoscopic removal of the obstructing food bolus is necessary. 
Endoscopy is generally the best initial test in such patients since endo­
scopic removal of the obstructing material is usually possible, and the 
presence of an underlying esophageal pathology can often be deter­
mined. Radiographs of the chest and neck should be considered before 
endoscopy in patients with fever, obstruction for ≥24 h, or ingestion of 
a sharp object, such as a fishbone. Radiographic contrast studies inter­
fere with subsequent endoscopy and are not advisable in most patients 
with a clinical picture of esophageal obstruction.
Gastric Outlet Obstruction 
Obstruction of the gastric outlet is 
commonly caused by gastric, duodenal, or pancreatic malignancy or 
chronic peptic ulceration with stenosis of the pylorus (Fig. 333-46). 
Patients vomit partially digested food many hours after eating. Gas­
tric decompression with a nasogastric tube and subsequent lavage for 
removal of retained material is the first step in treatment. Endoscopy is 
useful for diagnosis and treatment. Patients with benign pyloric steno­
sis may be treated with endoscopic balloon dilation of the pylorus, and 
a course of endoscopic dilation results in long-term relief of symptoms

PART 10
Disorders of the Gastrointestinal System
A
B
C
A
B
FIGURE 333-33  Contact coagulation for ulcer hemostasis. A. Duodenal ulcer with a visible vessel (arrow). B. Coagulation of the vessel with a contact thermal probe. 
C. Obliteration of the treated vessel (arrow).
FIGURE 333-34  Through-the-scope clip placement for ulcer hemostasis. A. Superficial duodenal ulcer with visible vessel (arrow). B. Hemostasis secured following 
placement of multiple through-the-scope clips.

A
B
FIGURE 333-35  Over-the-scope clip placement for ulcer hemostasis. A. Pyloric 
channel ulcer with visible vessel (arrow). B. Hemostasis secured following 
placement of an over-the-scope clip.
in ~50% of patients. Removable, fully covered lumen-apposing metal 
stents (LAMS) may also be used to treat benign pyloric stenosis 
(Video V5-16). Malignant gastric outlet obstruction can be relieved 
with endoscopically placed expandable stents across the obstruction in 
patients with inoperable malignancy (Video V5-17) or by EUS-guided 
gastroenterostomy to bypass the obstruction (Video V5-3).
Colonic Obstruction and Pseudoobstruction 
These con­
ditions both present with abdominal distention and discomfort, 
tympany, and a dilated colon on plain abdominal radiography. 
The radiographic appearance may be characteristic of a particular 
condition, such as sigmoid volvulus (Fig. 333-47). Both obstruc­
tion and pseudoobstruction may lead to colonic perforation if left 
untreated. Acute colonic pseudoobstruction is a form of colonic 
FIGURE 333-36  Esophageal varices.

A
CHAPTER 333
Gastrointestinal Endoscopy 
B
FIGURE 333-37  Endoscopic variceal ligation. A. Esophageal varices with red wale 
marks. B. Band ligation of varices.
ileus that is usually attributable to electrolyte disorders, narcotic 
and anticholinergic medications, immobility (as after surgery), or 
retroperitoneal hemorrhage or mass. Multiple causative factors are 
often present. Colonoscopy, water-soluble contrast enema, or CT 
may be used to assess for an obstructing lesion and differentiate 
obstruction from pseudoobstruction. One of these diagnostic studies 
should be strongly considered if the patient does not have clear risk 
factors for pseudoobstruction, if radiographs do not show air in the 
rectum, or if the patient fails to improve when underlying causes of 
pseudoobstruction have been addressed. The risk of cecal perforation 
in pseudoobstruction rises when the cecal diameter exceeds 12 cm, 
and decompression of the colon may be achieved using intravenous 
neostigmine or via colonoscopic decompression (Fig. 333-48). Most 
patients should receive a trial of conservative therapy (with correc­
tion of electrolyte disorders, discontinuation of offending medica­
tions, and increased mobilization) before undergoing an invasive 
decompressive procedure for colonic pseudoobstruction.
Acute colonic obstruction is an indication for urgent intervention. 
In the past, emergent diverting colostomy was usually performed 
with a subsequent second operation after bowel preparation to treat 
the underlying cause of obstruction. Colonoscopic placement of an

PART 10
Disorders of the Gastrointestinal System
A
B
C
A
B
FIGURE 333-39  Dieulafoy’s lesion. A. Actively spurting gastric Dieulafoy’s lesion. B. Coagulation of the lesion using a contact thermal probe. C. Hemostasis secured 
following contact coagulation (arrow). D. Histology of a gastric Dieulafoy’s lesion. A persistent caliber artery (arrows) is present in the gastric submucosa, immediately 
beneath the mucosa.
FIGURE 333-38  Gastric varices. A. Large gastric fundal varices with stigmata of recent bleeding (arrow). B. Injection of cyanoacrylate (glue) into the culprit gastric 
varix. C. Obliterated varix following glue injection on endoscopic follow-up at 1 month (arrow).

C
FIGURE 333-39  (Continued)
expandable stent is an alternative treatment option that can relieve 
malignant colonic obstruction without emergency surgery and permit 
bowel preparation for an elective one-stage operation (Fig. 333-49, 
Video V5-18).
■
■ACUTE BILIARY OBSTRUCTION
The steady, severe pain that occurs when a gallstone acutely obstructs 
the common bile duct often brings patients to seek medical atten­
tion. The diagnosis of a ductal stone is suspected when the patient is 
jaundiced or when serum liver tests or pancreatic enzyme levels are 
elevated; it is confirmed by transabdominal ultrasound, EUS, magnetic 
resonance cholangiopancreatography (MRCP), or direct cholangiog­
raphy (performed endoscopically, percutaneously, or during surgery). 
ERCP is the primary means of treating common bile duct stones (Figs. 
333-16 and 333-17), although they can also be removed by bile duct 
exploration at the time of cholecystectomy. Radiologic percutaneous 
biliary drainage may be required in some cases.
Bile Duct Imaging 
While transabdominal ultrasound diagnoses 
only a minority of bile duct stones, MRCP and EUS are >90% accurate 
and have an important role in diagnosis. Examples of these modalities 
are shown in Fig. 333-50.
FIGURE 333-40  Mallory-Weiss tear with an adherent clot at the gastroesophageal 
junction following forceful retching and vomiting.

D
If the suspicion for a bile duct stone is high and urgent treatment is 
required (as in a patient with obstructive jaundice and biliary sepsis), 
ERCP is the procedure of choice since it remains the gold standard 
for diagnosis and allows for immediate treatment (Video V5-19). If 
a persistent bile duct stone is relatively unlikely (as in a patient with 
gallstone pancreatitis), ERCP may be supplanted by less invasive imag­
ing techniques, such as EUS, MRCP, or intraoperative cholangiography 
performed during cholecystectomy, sparing some patients the risk and 
discomfort of ERCP.
CHAPTER 333
Gastrointestinal Endoscopy 
Ascending Cholangitis 
Charcot’s triad of jaundice, abdominal 
pain, and fever is present in ~70% of patients with ascending cholan­
gitis and biliary sepsis. These patients are managed initially with fluid 
resuscitation and intravenous antibiotics. Abdominal ultrasound is 
often performed to assess for gallbladder stones and bile duct dila­
tion. However, the bile duct may not be dilated early in the course of 
acute biliary obstruction. Medical management usually improves the 
patient’s clinical status, providing a window of ~24 h during which 
biliary drainage should be established, typically by ERCP. Undue 
delay can result in recrudescence of overt sepsis and increased mor­
bidity and mortality rates. In addition to Charcot’s triad, the presence 
of shock and confusion (Reynolds’s pentad) is associated with a high 
mortality rate and should prompt urgent intervention to restore biliary 
drainage.
Gallstone Pancreatitis 
Gallstones may cause acute pancreatitis 
as they pass through the ampulla of Vater. The occurrence of gallstone 
pancreatitis usually implies passage of a stone into the duodenum, and 
only ~20% of patients harbor a persistent stone in the ampulla or the 
common bile duct. Retained stones are more common in patients with 
jaundice, rising serum liver tests following hospitalization, severe pan­
creatitis, or superimposed ascending cholangitis.
Urgent ERCP decreases the morbidity rate of gallstone pancreati­
tis in a subset of patients with retained bile duct stones. It is unclear 
whether the benefit of ERCP is mainly attributable to treatment and 
prevention of ascending cholangitis or to relief of pancreatic duc­
tal obstruction. ERCP is warranted early in the course of gallstone 
pancreatitis if ascending cholangitis is suspected, especially in a 
jaundiced patient. Urgent ERCP may also benefit patients predicted 
to have severe pancreatitis using a clinical index of severity, such as 
the Glasgow or Ranson score. Since the benefit of ERCP is limited to 
patients with a retained bile duct stone, a strategy of initial MRCP or 
EUS for diagnosis decreases the utilization of ERCP in gallstone pan­
creatitis and improves clinical outcomes by limiting the occurrence of 
ERCP-related adverse events.

PART 10
Disorders of the Gastrointestinal System
A
B
C
FIGURE 333-41  Gastrointestinal vascular ectasias. A. Gastric antral vascular ectasia (“watermelon stomach”) characterized by stripes of prominent flat or raised vascular 
ectasias. B. Cecal vascular ectasia. C. Radiation-induced vascular ectasias of the rectum in a patient previously treated for prostate cancer.
ELECTIVE ENDOSCOPY
■
■DYSPEPSIA
Dyspepsia is a chronic or recurrent burning discomfort or pain in 
the upper abdomen that may be caused by diverse processes, such as 
gastroesophageal reflux, peptic ulcer disease, and “nonulcer dyspepsia,” 
a heterogeneous category that includes disorders of motility, sensa­
tion, and somatization. Gastric and esophageal malignancies are less 
common causes of dyspepsia. Careful history-taking allows accurate 
differential diagnosis of dyspepsia in only about half of patients. In 
the remainder, endoscopy can be a useful diagnostic tool, especially 
in patients whose symptoms are not resolved by Helicobacter pylori 
treatment or an empirical trial of acid-reducing therapy. Endoscopy 
should be performed at the outset in patients with dyspepsia and alarm 
features, such as weight loss, obstructive symptoms, or iron-deficiency 
anemia.
■
■GASTROESOPHAGEAL REFLUX DISEASE
When classic symptoms of gastroesophageal reflux are present, such 
as water brash and substernal heartburn, presumptive diagnosis and 
empirical treatment are often sufficient. Endoscopy is a sensitive test 
for diagnosis of esophagitis (Fig. 333-51), but it will miss nonero­
sive reflux disease (NERD) since some patients have symptomatic 
reflux without esophagitis. The most sensitive test for diagnosis of 
gastroesophageal reflux disease (GERD) is 24-h ambulatory pH and 
impedance monitoring. Endoscopy is indicated in patients with reflux 
symptoms refractory to antisecretory therapy; in those with alarm 
symptoms, such as dysphagia, weight loss, or gastrointestinal bleed­
ing; and in those with recurrent dyspepsia after treatment that is not 
clearly due to reflux on clinical grounds alone. Endoscopy should be 
considered in patients with long-standing GERD, as they have a sixfold 
increased risk of harboring Barrett’s esophagus compared to patients 
with <1 year of reflux symptoms.

FIGURE 333-42  Colonic diverticula.
Barrett’s Esophagus and Esophageal Squamous Dysplasia 

Barrett’s esophagus is specialized columnar metaplasia that replaces 
the normal squamous mucosa of the distal esophagus in some persons 
with GERD. Barrett’s epithelium is a major risk factor for adenocarci­
noma of the esophagus and is readily detected endoscopically, due to 
proximal displacement of the squamocolumnar junction (Fig. 333-6). 
A screening EGD for Barrett’s esophagus should be considered in 
patients with a chronic (≥10 year) history of GERD symptoms, even 
if their symptoms have been mild. Endoscopic biopsy is the gold 
standard for confirmation of Barrett’s esophagus and for dysplasia or 
cancer arising in Barrett’s mucosa.
Periodic EGD with biopsies is recommended for surveillance of 
patients with Barrett’s esophagus. Endoscopic resection (EMR or ESD) 
and/or ablation are treatment options when high-grade dysplasia or 
intramucosal cancer are found in the Barrett’s mucosa. Both endo­
scopic therapy and periodic surveillance are acceptable options in 
patients with Barrett’s esophagus and low-grade dysplasia. Radiofre­
quency ablation (RFA) is the most common ablative modality used 
for endoscopic treatment of Barrett’s esophagus, and other modalities, 
such as cryotherapy, are also available.
Esophageal squamous dysplasia is the precursor lesion of esophageal 
squamous cell cancer (ESCC), the most common type of esophageal 
malignancy worldwide. Endoscopic detection of esophageal squa­
mous dysplasia often requires specialized imaging methods, such as 
chromoendoscopy with Lugol’s iodine solution. Once detected, it can 
be treated endoscopically with EMR, ESD, or RFA (Fig. 333-52). Pop­
ulation-based screening for esophageal squamous dysplasia has been 
shown to decrease the occurrence of ESCC in high-incidence regions.
■
■PEPTIC ULCER
Peptic ulcer classically causes epigastric gnawing or burning, often 
occurring nocturnally and promptly relieved by food or antacids. 
Although endoscopy is the most sensitive diagnostic test for peptic 
ulcer, it is not a cost-effective strategy in young patients with ulcer-like 
dyspeptic symptoms unless endoscopy is available at low cost. Patients 
with suspected peptic ulcer should be evaluated for H. pylori infection. 
Serology (which diagnoses past or current infection), urea breath test­
ing (current infection), and stool tests (current infection) are noninva­
sive and less costly than endoscopy with biopsy. Patients aged >50 and 
those with alarm symptoms or persistent symptoms despite treatment 
should undergo endoscopy to exclude malignancy.
■
■NONULCER DYSPEPSIA
Nonulcer dyspepsia may be associated with bloating and, unlike peptic 
ulcer, tends not to remit and recur. Most patients describe persis­
tent symptoms despite acid-reducing, prokinetic, or anti-Helicobacter 

A
CHAPTER 333
Gastrointestinal Endoscopy 
B
C
FIGURE 333-43  Diverticular hemorrhage. A. Actively bleeding sigmoid diverticulum. 
B. Treatment of the bleeding vessel at the dome of the diverticulum with a contact 
thermal probe. C. Hemostasis secured following contact coagulation with tattoo 
injection to aid future localization.

FIGURE 333-44  Esophageal food impaction. Meat bolus impacted in the distal 
esophagus.
therapy and are referred for endoscopy to exclude a refractory ulcer 
and assess for other causes. Although endoscopy is useful for excluding 
other diagnoses, its impact on the treatment of patients with nonulcer 
dyspepsia is limited.
PART 10
Disorders of the Gastrointestinal System
■
■DYSPHAGIA
About 50% of patients presenting with difficulty swallowing have a 
mechanical obstruction; the remainder have a motility disorder, such 
as achalasia or diffuse esophageal spasm, or an inflammatory disorder, 
such as eosinophilic esophagitis. Careful history-taking often points to 
a presumptive diagnosis and leads to the appropriate use of diagnostic 
tests. Esophageal strictures (Fig. 333-53) typically cause progres­
sive dysphagia, first for solids, then for liquids; motility disorders 
often cause intermittent dysphagia for both solids and liquids. Some 
underlying disorders have characteristic historic features: Schatzki’s 
ring (Fig. 333-54) causes episodic dysphagia for solids, typically at the 
beginning of a meal; oropharyngeal motor disorders typically present 
with difficulty initiating deglutition (transfer dysphagia) and nasal 
reflux or coughing with swallowing; and achalasia may cause nocturnal 
regurgitation of undigested food from the esophagus.
FIGURE 333-45  Esophageal foreign body. Intentionally ingested toothbrush 
impacted in the esophageal lumen.

A
B
C
FIGURE 333-46  Gastric outlet obstruction due to pyloric stenosis. A. Nonsteroidal 
anti-inflammatory agent–induced ulcer disease with severe stenosis of the pylorus 
(arrow). B. Balloon dilation of the stenosis. C. Appearance of pyloric ring after 
dilation.
When mechanical obstruction is suspected, endoscopy is a useful 
initial diagnostic test, since it permits immediate biopsy and/or dilation 
of strictures, masses, or rings. The presence of linear furrows and multiple 
corrugated rings throughout a narrowed esophagus should raise sus­
picion for eosinophilic esophagitis, an increasingly recognized cause 
of recurrent dysphagia and food impaction (Fig. 333-55). Blind or 
forceful passage of an endoscope may lead to perforation in a patient 
with stenosis of the cervical esophagus or a Zenker’s diverticulum 
(Fig. 333-56), but gentle passage of an endoscope under direct visual 
guidance is reasonably safe. Endoscopy can miss a subtle stricture or 
ring in some patients.
When transfer dysphagia is evident or an esophageal motility disor­
der is suspected, esophageal radiography and/or a video-swallow study 
are the best initial diagnostic tests. The oropharyngeal swallowing 
mechanism, esophageal peristalsis, and the lower esophageal sphincter

A
B
C
FIGURE 333-47  Sigmoid volvulus. A. Abdominal x-ray showing characteristic 
radiologic appearance of a “bent inner tube.” B. Site of sigmoid torsion identified 
at colonoscopy C. Significantly dilated colonic lumen proximal to the sigmoid twist 
with mild ischemic-appearing mucosal changes.

A
B
FIGURE 333-48  Acute colonic pseudoobstruction. A. Acute colonic dilation 
occurring in a patient soon after knee surgery. B. Colonoscopic placement of 
decompression tube with marked improvement in colonic dilation.
CHAPTER 333
can all be assessed. In some disorders, subsequent esophageal manom­
etry is required for diagnosis.
Various causes of dysphagia are amenable to endoscopic therapy. 
Benign strictures, rings, and webs can be dilated using a through-thescope balloon (Fig. 333-57) or a tapered polyvinyl dilator passed over 
a guide wire. In some instances, fibrotic strictures may respond to 
needle-knife electroincision (Fig. 333-58) when they prove refractory 
to dilation. Self-expanding esophageal stents can be used to palliate 
dysphagia from malignant obstruction (Fig. 333-59), and flexible 
endoscopic cricopharyngeal myotomy is an option for Zenker’s diver­
ticulum (Video V5-20). Recent advances in third-space (submucosal) 
endoscopy have enabled the development of procedures, such as 
POEM (Video V5-21) and POET (Video V5-22), for the management 
of achalasia and select subepithelial esophageal tumors, respectively.
Gastrointestinal Endoscopy 
■
■ENDOSCOPIC TREATMENT OF OBESITY
A significant proportion of Americans are overweight or obese, and 
obesity-associated diabetes has become a major public health prob­
lem. Bariatric surgery is the most effective weight-loss intervention, 
decreasing long-term mortality in obese persons, but many patients 
choose not to undergo surgery. Endoscopic treatments for obesity have 
been developed and include insertion of an intragastric balloon or duo­
denojejunal bypass liner, placement of a percutaneous gastric tube for 
aspiration of gastric contents after meals, duodenal mucosal electro­
poration, or endoscopic sleeve gastroplasty, which utilizes endoscopic 
suturing to narrow the lumen of the gastric body (Video V5-23). 
Prospective trials show that these treatments induce total-body weight 
loss of 7–20% and provide varying degrees of glycemic control and 
improvement in other diseases linked to obesity, such as metabolicassociated fatty liver disease (MAFLD). Additional endoscopic modali­
ties are undergoing clinical trials. The efficacy of bariatric endoscopy 
may approach that of bariatric surgery in the short term. Long-term 
outcomes are still under evaluation.
■
■TREATMENT OF MALIGNANCIES
Endoscopy plays an important role in the treatment of gastrointestinal 
malignancies. Early-stage malignancies limited to the mucosal and 
superficial submucosal layers may be resected using the techniques

PART 10
Disorders of the Gastrointestinal System
A
B
C
FIGURE 333-49  Obstructing colonic carcinoma. A. Colonic adenocarcinoma causing marked luminal narrowing of the distal transverse colon. B. Endoscopic placement of 
a self-expandable metal stent. C. Radiograph of expanded stent across the obstructing tumor with a residual waist (arrow).
A
B
C
FIGURE 333-50  Methods of bile duct imaging. Arrows mark bile duct stones. A. Endoscopic ultrasound (EUS) demonstrating a hyperechoic stone with acoustic shadowing 
(arrowhead). B. Magnetic resonance cholangiopancreatography (MRCP). C. Helical computed tomography (CT).

A
C
FIGURE 333-51  Causes of esophagitis. A. Severe reflux esophagitis with mucosal ulceration and friability. B. Cytomegalovirus esophagitis. C. Herpes simplex virus 
esophagitis with target-type shallow ulcerations. D. Candida esophagitis with white plaques adherent to the esophageal mucosa.
of EMR (Video V5-5) or ESD (Video V5-6). RFA and cryotherapy are 
effective modalities for ablative treatment of high-grade dysplasia and 
intramucosal cancer in Barrett’s esophagus (Video V5-24). Gastroin­
testinal stromal tumors can be removed en bloc by endoscopic fullthickness resection (Video V5-4). In general, endoscopic techniques 
offer the advantage of a minimally invasive approach to treatment but 
rely on other imaging techniques (such as CT, magnetic resonance 
imaging [MRI], positron emission tomography [PET], and EUS) to 
exclude distant metastases or locally advanced disease better treated by 
surgery or other modalities. The decision to treat an early-stage gas­
trointestinal malignancy endoscopically is often made in collaboration 
with a surgeon and/or oncologist.
A
FIGURE 333-52  Early squamous cell cancer. A. Nodularity in the distal esophagus due to T1 esophageal squamous cell cancer. B. The nodular lesion remains unstained 
following chromoendoscopy with Lugol’s solution without additional unstained areas. C. Circumferential mucosal incision around the lesion. D. Resection defect following 
en bloc removal of the lesion via endoscopic submucosal dissection.

B
D
CHAPTER 333
Endoscopic palliation of gastrointestinal malignancies relieves 
symptoms and, in many cases, prolongs survival. Malignant obstruc­
tion can be relieved by endoscopic stent placement (Figs. 333-18, 
333-49, 333-59, and 333-60; Videos V5-17 and V5-18), and malignant 
gastrointestinal bleeding can be palliated endoscopically as well. EUSguided celiac plexus neurolysis may relieve pancreatic cancer pain.
Gastrointestinal Endoscopy 
■
■ANEMIA AND OCCULT BLOOD IN THE STOOL
Iron-deficiency anemia may be attributed to poor iron absorption 
(as in celiac sprue) or, more commonly, chronic blood loss. Intestinal 
bleeding should be strongly suspected in men and postmenopausal 
women with iron-deficiency anemia, and colonoscopy is indicated in 
B

C
FIGURE 333-52  (Continued)
such patients, even in the absence of detectable occult blood in the 
stool. Approximately 30% will have large colonic polyps or colorectal 
cancer, and a few patients will have colonic vascular lesions. When a 
convincing source of blood loss is not found in the colon, upper gastrointestinal endoscopy should be considered; if no lesion is found, 
duodenal biopsies should be obtained to exclude sprue (Fig. 333-61). 
Small-bowel evaluation with capsule endoscopy (Fig. 333-62), CT or 
magnetic resonance (MR) enterography, or deep enteroscopy may be 
appropriate if both EGD and colonoscopy are unrevealing.
PART 10
Disorders of the Gastrointestinal System
Tests for occult blood in the stool detect hemoglobin or the heme 
moiety and are most sensitive for colonic blood loss, although they will 
also detect larger amounts of upper gastrointestinal bleeding. Patients 
with occult blood in the stool should undergo colonoscopy to diagnose 
or exclude colorectal neoplasia, especially if they are >50 years old or 
have a family history of colonic neoplasia. Whether upper endoscopy 
is also indicated depends on the patient’s symptoms.
The small intestine may be the source of chronic intestinal bleeding, especially if colonoscopy and upper endoscopy are not diagnostic. The utility of small-bowel evaluation varies with the clinical 
setting and is most important in patients in whom bleeding causes 
A
B
FIGURE 333-53  Esophageal stricture. A. Peptic stricture associated with esophagitis. B. Balloon dilation of peptic stricture.

D
chronic or recurrent anemia. In contrast to the low diagnostic yield 
of small-bowel radiography, positive findings on capsule endoscopy 
are seen in 50–70% of patients with suspected small intestinal bleeding. The most common finding is mucosal vascular ectasia. CT and 
MR enterography accurately detect small-bowel masses and Crohn’s 
disease and are also useful for initial small-bowel evaluation. Deep 
enteroscopy may follow capsule endoscopy for biopsy of lesions or to 
provide specific therapy, such as argon plasma coagulation of vascular ectasias (Fig. 333-63).
■
■COLORECTAL CANCER SCREENING
The majority of colon cancers develop from preexisting colonic adenomas, and colorectal cancer can be largely prevented by the detection 
and removal of adenomatous polyps (Video V5-25). The choice of 
screening strategy for an asymptomatic person depends on personal 
and family history. Individuals with inflammatory bowel disease, a history of colorectal polyps or cancer, family members with adenomatous 
polyps or cancer, or certain familial cancer syndromes (Fig. 333-64) 
are at increased risk for colorectal cancer. An individual without these 
factors is generally considered at average risk.

FIGURE 333-54  Schatzki’s ring at the gastroesophageal junction.
Screening strategies are summarized in Table 333-3. While fecal 
immunochemical tests (FITs) for heme or stool tests for occult blood 
have been shown to decrease the mortality rate from colorectal cancer, 
they do not detect some cancers and many polyps. FIT-DNA multitar­
geted stool DNA tests appear to be more sensitive, but direct visualiza­
tion of the colon is the gold standard method for detection of polyps 
and cancers and remains a preferred screening strategy. Sigmoidoscopy 
is also used for colorectal cancer screening. However, the distribution 
of colon cancers has changed in the United States over time, with 
proportionally fewer rectal and left-sided cancers than in the past. 
Large American studies of colonoscopy for screening of average-risk 
individuals show that cancers are roughly equally distributed between 
the left and right colon and half of patients with right-sided lesions 
have no polyps in the left colon. Visualization of the entire colon thus 
appears to be the optimal strategy for colorectal cancer screening and 
prevention.
Computed tomography colonography (CTC) is a radiologic tech­
nique that images the colon with CT following rectal insufflation of 
FIGURE 333-55  Eosinophilic esophagitis. Multiple circular rings of the esophagus 
creating a corrugated appearance and an impacted grape at the narrowed 
esophagogastric junction. The diagnosis requires biopsy with histologic finding of 
≥15 eosinophils/high-power field.

CHAPTER 333
A
Gastrointestinal Endoscopy 
B
FIGURE 333-56  Zenker’s diverticulum. A. Contrast esophagography demonstrates 
a moderate-sized Zenker’s diverticulum. B. Endoscopic view of the Zenker’s 
diverticulum (left) relative to the true esophageal lumen (right) separated by the 
diverticular septum. C. Flexible endoscopic diverticulotomy using an electrosurgical 
knife. D. Appearance after diverticulotomy.
the colonic lumen. Computer rendering of CT images generates an 
electronic display of a virtual “flight” along the colonic lumen, simulat­
ing colonoscopy (Fig. 333-65). Findings detected during CTC often 
require subsequent conventional colonoscopy for confirmation and 
treatment.
■
■DIARRHEA
Most cases of diarrhea are acute, self-limited, and due to infections 
or medication. Chronic diarrhea (lasting >4–6 weeks) is more often 
due to a primary inflammatory, malabsorptive, or motility disorder; is 
less likely to resolve spontaneously; and generally, requires diagnostic 
evaluation. Patients with chronic diarrhea or severe, unexplained acute 
diarrhea often undergo endoscopy if stool tests for pathogens are

C
PART 10
Disorders of the Gastrointestinal System
D
FIGURE 333-56  (Continued)
unrevealing. The choice of endoscopic testing depends on the clinical 
setting.
Patients with colonic symptoms and findings such as bloody 
diarrhea, tenesmus, fever, or leukocytes in stool generally undergo 
sigmoidoscopy or colonoscopy to assess for colitis (Fig. 333-9). Sig­
moidoscopy is an appropriate initial test in most patients. Conversely, 
patients with symptoms and findings suggesting small-bowel disease, 
such as large-volume watery stools, substantial weight loss, and malab­
sorption of iron, calcium, or fat, may undergo upper endoscopy with 
duodenal aspirates for assessment of bacterial overgrowth and biopsies 
for assessment of mucosal diseases, such as celiac sprue.
Many patients with chronic diarrhea do not fit either of these pat­
terns. In the setting of a long-standing history of altered bowel habits 
dating to early adulthood, without findings such as blood in the stool 
or anemia, a diagnosis of irritable bowel syndrome may be made 
without direct visualization of the bowel and by relying on appropri­
ate blood tests (including complete blood count, C-reactive protein 
and antibody tests for celiac disease) to screen for other diagnoses. 
Steatorrhea and upper abdominal pain may prompt evaluation of 
the pancreas rather than the gut. Patients whose chronic diarrhea is 
not easily categorized often undergo initial colonoscopy to examine 
the entire colon and terminal ileum for inflammatory or neoplastic 
disease (Fig. 333-66).

A
B
C
FIGURE 333-57  Endoscopic management of peptic stricture. A. Peptic stricture. 
B. Through-the-scope balloon dilation of stricture. C. Improvement in luminal 
diameter after dilation.
■
■MINOR HEMATOCHEZIA
Bright red blood passed with or on formed brown stool usually has an 
anal, rectal, or sigmoid source (Fig. 333-67). Even trivial amounts of 
hematochezia should be investigated with colonoscopy and/or flexible 
sigmoidoscopy together with anoscopy to exclude polyps or cancers, 
especially in patients >40 years old and those with a personal or fam­
ily history of colorectal polyps or cancer. Patients reporting red blood 
on the toilet tissue only, without blood in the toilet or on the stool, 
are generally bleeding from a lesion in the anal canal; careful external 
inspection, digital examination, and sigmoidoscopy with anoscopy 
may be sufficient for diagnosis in such cases.
■
■PANCREATITIS
About 20% of patients with pancreatitis have no identified cause after 
routine clinical investigation (including a review of medication and 
alcohol use; measurement of serum triglyceride, calcium, and immu­
noglobulin G subclass 4 [IgG4] levels; abdominal ultrasonography; 
and CT or MRI). Endoscopic assessment leads to a specific diagnosis

A
B
FIGURE 333-58  Endoscopic management of an esophagogastric anastomotic stricture. A. Recurrent anastomotic stricture despite periodic balloon dilation. B. Needle-knife 
electroincision of stricture. C. Improvement in luminal opening after therapy.
in the majority of such patients, often altering clinical management. 
Endoscopic investigation is particularly appropriate if the patient has 
had more than one episode of pancreatitis.
Microlithiasis, or the presence of microscopic crystals in bile, is 
a leading cause of previously unexplained acute pancreatitis and is 
sometimes seen during abdominal ultrasonography as layering sludge 
or flecks of floating, echogenic material in the gallbladder. EUS may 
identify microlithiasis or gallstones not seen on transabdominal 
ultrasound.
Previously undetected chronic pancreatitis, pancreatic malignancy, 
or pancreas divisum may be diagnosed by either ERCP or EUS. Auto­
immune pancreatitis is often suspected based on CT, MRI, or serologic 
findings, but it may first become apparent during EUS and may require 
EUS-guided pancreatic biopsy for histologic diagnosis.
Severe pancreatitis often results in pancreatic fluid collections. 
Symptomatic pseudocysts and areas of walled-off pancreatic necro­
sis can be drained into the stomach or duodenum endoscopically, 
using transpapillary and transmural endoscopic techniques. Pancreatic 
necrosis can be debrided by direct endoscopic necrosectomy (Video 
V5-2) via an endoscopically created transmural drainage site.
■
■CANCER STAGING
Local staging of esophageal, gastric, pancreatic, bile duct, and rectal 
cancers can be obtained with EUS (Fig. 333-20). EUS with fine-needle 
aspiration (Fig. 333-21) or biopsy currently provides the most accurate 
preoperative assessment of local tumor and nodal staging, but it does 
not detect many distant metastases. Details of the local tumor stage 
can guide treatment decisions, including resectability and need for 
neoadjuvant therapy. EUS with transesophageal needle biopsy may 
A
FIGURE 333-59  Palliation of malignant dysphagia. A. Obstructing distal esophageal cancer. B. Palliative stent placement.

C
also be used to assess the presence of non-small-cell lung cancer in 
mediastinal nodes.
OPEN-ACCESS ENDOSCOPY
Direct scheduling of endoscopic procedures by providers without 
preceding gastroenterology consultation, or open-access endoscopy, 
is common. When the indications for endoscopy are clear-cut and 
appropriate, the procedural risks are low, and the patient understands 
what to expect, open-access endoscopy streamlines patient care and 
decreases costs.
CHAPTER 333
Patients referred for open-access endoscopy should have a recent 
history, physical examination, and medication list that are available 
for review when the patient comes to the endoscopy suite. Patients 
with unstable or symptomatic cardiovascular or respiratory conditions 
should not be referred directly for open-access endoscopy. Those with 
particular conditions who are undergoing certain procedures should 
be prescribed prophylactic antibiotics before endoscopy (Table 333-1). 
In addition, patients taking anticoagulants and/or antiplatelet drugs 
may require adjustment of these agents before endoscopy based on the 
procedural risk for bleeding and their underlying risk for a thrombo­
embolic event (Table 333-2).
Gastrointestinal Endoscopy 
Common indications for open-access EGD include dyspepsia 
resistant to a trial of appropriate therapy, dysphagia, gastrointestinal 
bleeding, and persistent anorexia or early satiety. Open-access colo­
noscopy is often requested in men or postmenopausal women with 
iron-deficiency anemia, in patients with hematochezia or occult blood 
in the stool, in patients with a previous history of colorectal adeno­
matous polyps or cancer, and for colorectal cancer screening. Flexible 
sigmoidoscopy is commonly performed as an open-access procedure.
B

A
PART 10
Disorders of the Gastrointestinal System
C
FIGURE 333-60  Placement of biliary and duodenal self-expanding metal stents (SEMS) for obstruction caused by pancreatic cancer. A. Endoscopic retrograde 
cholangiopancreatography (ERCP) demonstrates a distal bile duct stricture (arrow). B. A biliary SEMS is placed. C. Contrast injection demonstrates a duodenal stricture 
(arrow). D. Biliary and duodenal SEMS in place.
FIGURE 333-61  Celiac sprue. Scalloped duodenal folds in a patient with celiac 
sprue.

B
D
When patients are referred for open-access colonoscopy, the pri­
mary care provider may need to choose a colonic preparation. Com­
monly used oral preparations include polyethylene glycol lavage 
solution, with or without citric acid. A “split-dose” regimen improves 
the quality of colonic preparation. Osmotic purgative preparations 
(such as sodium phosphate or magnesium citrate) are also effective 
but may cause fluid and electrolyte abnormalities and renal toxicity, 
especially in patients with renal failure or congestive heart failure and 
those >70 years of age.
FIGURE 333-62  Capsule endoscopy. Images of a mildly scalloped jejunal fold (left) 
and an ileal tumor (right) in a patient with celiac sprue. (Images courtesy of Dr. 
Elizabeth Rajan; with permission.)

A
C
FIGURE 333-63  Small-bowel vascular ectasia. A. Actively bleeding mid-jejunal vascular ectasia identified by double-balloon enteroscopy. B. Ablation of vascular ectasia 
with argon plasma coagulation (APC). C. Hemostasis secured following APC.
FIGURE 333-64  Familial adenomatous polyposis. Numerous colon polyps in a patient with familial adenomatous polyposis syndrome.

B
CHAPTER 333
Gastrointestinal Endoscopy

TABLE 333-3  Colorectal Cancer Screening Strategies
 
CHOICES/RECOMMENDATIONS
COMMENTS
Average-Risk Patients
Asymptomatic individuals between 45 and 75 years of age
Colonoscopy every 10 yearsa
Gold standard cancer prevention strategy
 
Multitargeted stool DNA test every 1–3 years 
FIT or HSgFOBT every year, with or without flexible 
sigmoidoscopy every 10 years
 
CT colonography every 5 years
Colonoscopy if results are positive
 
Flexible sigmoidoscopy every 5 years
Does not detect proximal colon polyps and cancers; 
colonoscopy if an adenomatous polyp is found
Asymptomatic individuals > 75 years of age
Selective screening
Consider patient’s overall health, results of previous 
screening exams, and preferences
Personal History of Polyps or CRC
1–2 small (<10 mm) tubular adenomas
Repeat colonoscopy in 7–10 yearsa
Assuming complete polyp resection. Interval may vary 
based on prior personal history and family history
3–4 tubular adenomas <10 mm
Repeat colonoscopy in 3–5 yearsa; subsequent 
colonoscopy based on findings
5–10 tubular adenomas <10 mm
Repeat colonoscopy in 3 yearsa
Assuming complete polyp resection
>10 adenomas on a single exam
Repeat colonoscopy in 1 yeara
Consider evaluation for FAP or HNPCC; see 
recommendations below
Adenoma ≥10 mm, or adenoma with tubulovillous or 
villous histology, or high-grade dysplasia
Repeat colonoscopy in 3 yearsa
Assuming complete polyp resection
Piecemeal removal of any sessile polyp
Exam in 6 months to verify complete removal
 
Small (<1 cm) hyperplastic polyps of sigmoid and 
rectum
Repeat colonoscopy in 10 yearsa
Those with hyperplastic polyposis syndrome merit more 
frequent follow-up
Hyperplastic polyp ≥10 mm
Repeat colonoscopy in 3–5 yearsa
 
PART 10
Disorders of the Gastrointestinal System
1–2 SSPs <10 mm
Repeat colonoscopy in 5–10 yearsa
Assuming complete polyp resection
3–4 SSPs <10 mm
Repeat colonoscopy in 3–5 yearsa
Assuming complete polyp resection
5–10 SSPs <10 mm, or any single SSP ≥10 mm, or any 
SSP with dysplasia
Repeat colonoscopy in 3 yearsa
Assuming complete polyp resection. Serrated polyposis 
syndrome merits more frequent follow-up
Piecemeal removal of serrated polyp ≥1 cm
Exam in 2–6 months to verify complete removal
 
Colon cancer
Evaluate entire colon around the time of resection, 
then repeat colonoscopy in 1 yeara
Subsequent colonoscopy in 3 years if the 1-year 
examination is normal
Inflammatory Bowel Disease
Long-standing (>8 years) ulcerative pancolitis or 
Crohn’s colitis, or left-sided ulcerative colitis 

of >15 years’ duration
Colonoscopy with biopsies every 1–2 years
Consider chromoendoscopy or other advanced imaging 
techniques for detection of flat dysplasia during 
colonoscopy
Family History of Polyps or CRC
First-degree relatives with only small tubular adenomas
Same as average risk
 
One first-degree relative with CRC or advanced 
adenoma at age ≥60 years
Begin screening starting at age 40, tests and 
intervals per average-risk recommendations
One first-degree relative with CRC or advanced 
adenoma at age <60 years, or two first-degree relatives 
with CRC or advanced adenomas at any age
Colonoscopy every 5 years beginning at age 

40 years or 10 years before the age at diagnosis of 
the youngest affected relative, whichever is earlier
Familial adenomatous polyposis (FAP)
Sigmoidoscopy or colonoscopy annually, beginning 
at age 10–12 years
Hereditary nonpolyposis colorectal cancer (HNPCC; 
Lynch syndrome)   
 
 
Serrated polyposis syndrome (SPS)   
 
Colonoscopy every 2 years beginning at age 20–25 
years (or 10 years younger than the youngest firstdegree relative was when diagnosed with CRC) until 
age 40, then annually thereafter   
Colonoscopy at age 40 (or the same age at which 
the youngest first-degree relative was when 
diagnosed with SPS, or 10 years younger than the 
youngest first-degree relative was when diagnosed 
with CRC), then every 1–2 years thereafter 
Colonoscopy every 3–5 years beginning 10 years 
before the age at diagnosis of the youngest affected 
relative
 
 
Family colon cancer syndrome X
aAssumes good colonic preparation and complete examination to cecum. bHigh-risk adenoma: any adenoma ≥1 cm in size or containing high-grade dysplasia or villous features.
Abbreviations: CRC, colorectal cancer; CT, computed tomography; FIT, fecal immunochemical test; HSgFOBT, high-sensitivity guaiac fecal occult blood test; SSP, sessile 
serrated polyp.
Sources: Adapted from U.S. Preventative Services Task Force Draft Guidelines finalized May 18, 2021 (https://www.uspreventiveservicestaskforce.org/uspstf/
recommendation/colorectal-cancer-screening) and American Cancer Society Guidelines (https://www.cancer.org/cancer/types/colon-rectal-cancer/detection-diagnosisstaging/acs-recommendations.html), both accessed on September 15, 2023, as well as the following articles: DK Rex et al: Colorectal cancer screening: Recommendations 
for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Gastroenterology 153:307, 2017; S Gupta et al: Recommendations for follow-up after 
colonoscopy and polypectomy: A consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology 158:1131, 2020; G Mankaney et al: Serrated 
polyposis syndrome. Clin Gastroenterol Hepatol 18:777, 2020.

Less sensitive than colonoscopy; colonoscopy if results 
are positive
Less sensitive than colonoscopy; colonoscopy if results 
are positive
Assuming complete polyp resection
 
 
Consider genetic counseling and testing; consider 
screening family members
Consider histologic evaluation for microsatellite 
instability in tumor specimens of patients who meet 
modified Bethesda criteria; consider genetic counseling 
and testing, consider screening family members 
Consider screening family members, even of patients 
with multiple serrated polyps who do not meet SPS 
criteria