15.14 Colonic diverticular disease 2960

15.14 Colonic diverticular disease 2960

ESSENTIALS Colonic diverticula are herniations of mucosa through the bowel musculature. They are seen most often in the sigmoid and descending colon, with a prevalence of up to 65% in people over the age of 80 in European populations. They are uncommon in African and Asian countries, where the prevalence is only 0.2%. A lifelong diet deficient in dietary fibre is associated with their development, but it is not known why some diverticula become symptomatic. Diverticula are usually discovered incidentally, but symptoms which are attributable to diverticular disease include colicky abdom- inal pain and bloating, often accompanied by a change in bowel habit with the passage of broken, pellety stools after considerable straining. All patients with such presentation should be investigated to exclude rectal or sigmoid carcinoma. Treatment is with reassurance that there is no serious underlying disease, a high-​fibre diet, and—​for patients with pain—​antispasmodics such as mebeverine. Elective resection may be indicated in the few patients who have repeated severe attacks. Complications of diverticular disease include diverticulitis, pericolic abscess formation, peritonitis, intestinal obstruction, haem- orrhage, and fistula formation. Acute diverticulitis typically presents with pain and tenderness over the left lower abdomen, and the pa- tient may have pyrexia, malaise, anorexia, and nausea. Treatment is with rest, broad-​spectrum antibiotics, and analgesia. Resection of the sigmoid colon may be necessary if symptoms fail to resolve or recur, or for patients with complications (peritonitis, fistula, obstruc- tion). Overall, percutaneous drainage, antibiotic treatment, and ex- pectant policies have reduced the need for both acute and elective surgical treatment. Epidemiology The term diverticular disease was first described in the medical literature at the turn of the 20th century. The first case of resec- tion for a complication of diverticular disease was documented by Mayo in 1907. Autopsy studies in the United Kingdom and Australia have shown that the prevalence of colonic diverticula increases with age. It is less than 5% at the age of 40 years, at the age of 60 it is 30%, and it rises to 65% by the age of 80. In Edinburgh, 23% of all barium enemas demonstrated diverticula. The annual incidence increased from 0.17 in 1000 in those under 45 years to 5.7 in 1000 in those over 75 years of age. Subtle sex differences have been observed: women were affected more than men. A study in eastern England measured the incidence of perforation sec- ondary to diverticular disease. They observed that there was in- crease in perforation with age and after adjusting for age there was a higher incidence in males (5.1 in 100 000/​year in males and 3.6 in 100 000/​year in females). In spite of the introduction of high-​fibre diets, there is no evidence that the incidence of diverticular disease is declining. A recent review has observed a slight rise in the preva- lence of perforated diverticular disease in Western countries from 2.4 in 100 000 in 1986 to 3.8 in 100 000 in 2000. By contrast, colonic diverticulosis is very rare in African and Asian countries where the prevalence is 0.2%. Interestingly, in a re- view of 600 Japanese patients with diverticular disease, right-​sided colonic disease was demonstrated in 70%. This geographical distri- bution is not simply due to genetic factors and race, as Asian and African migrants moving to the United Kingdom or the United States of America have acquired the prevalence of disease seen in the native white population, which suggests an environmental risk factor, thought to be dietary. This is in agreement with the observa- tion that patients presenting with complicated diverticular disease have a low intake of dietary fibre, and vegetarians have a low inci- dence of the disease. Multiple other factors have also been impli- cated in the development of diverticular disease, including lack of physical exercise, obesity, smoking, and immunosuppression. Aetiology Diverticular disease is said to be a disease of the 20th century and in the United Kingdom there is a correlation between the rising in- cidence at the beginning of the 20th century and an increased con- sumption of refined flour and sugar. Sugar consumption has trebled since 1860, and in the late 1870s the stone grinding of flour was re- placed by roller milling, which removes more fibre. Modern white bread and some brown breads contain little fibre compared with the 15.14 Colonic diverticular disease Nicolas C. Buchs, Roel Hompes, Shazad Q. Ashraf, and Neil J.McC. Mortensen

15.14  Colonic diverticular disease 2961 amount in wholemeal bread, which was previously a staple part of the diet. The development of diverticula may be heavily influenced by a lifelong diet deficient in dietary fibre. A high-​fibre diet is related to reduced gut transit times, with less strain on the colon. Modern, fibre-​deficient diets on the other hand give rise to stiff, viscous stools that need high intracolonic pressures to propel them. High luminal pressures cause a protrusion of the mucosa through vul- nerable points in the sigmoid and descending colon. These usually occur at sites where colonic blood vessels penetrate the wall. This hypothesis is supported by the observation that, although basal intracolonic pressures are similar in health and diverticular disease, when the diseased colon is activated by emotion, eating, mechanical stimuli, or drugs such as morphine or prostigmine, high pressures are generated in those segments that have diverticula. This is due to hypersegmentation by the colonic smooth muscle, and the dif- ference has been recorded in the earliest stage of disease and may explain its progressive nature. In symptomatic patients, an increase in dietary fibre causes a relief of symptoms in many cases. Changes in the colon wall also play a part. With age, and fol- lowing episodes of diverticulitis, the colonic wall becomes stiff and less distensible, aggravating the effects of raised intracolonic pres- sure. An increase in elastin and changes in collagen have been re- ported. Diabetic patients are prone to diverticular disease at an earlier stage, suggesting a defect in glycosylation of colonic collagen with advancing age. In those with connective tissue disorders such as Ehlers–​Danlos syndrome or Marfan’s disease, diverticula are also seen at an unusually early age. Pathogenesis of diverticular complications The distinction between symptomatic and asymptomatic diver- ticular disease is important, for although something is known about the formation of diverticula, it is not known why some diverticula become symptomatic. A large American cohort study has shown that high red meat in- take and a diet deficient in fruit and vegetables multiplied the risk of developing symptomatic diverticular disease threefold. The benefits of fibre are thought to be secondary to their effect in reducing gut transit times and colonic segmentation. Secondly, there may be a symbiotic effect related to the formation of short-​chain fatty acids, which are released after bacterial action on fibre. On the other hand, certain chemicals in cooked meat such as heterocyclic amines are thought to trigger cytotoxicity of colonocytes. The pathogenesis of diverticular perforation is not clear. However, rises in intradiverticular pressure are thought to play a role. This may be secondary to a blockage of the mouth of a diverticulum with faecal material or colonic segmentation. Once the pressure rises over a critical threshold, focal ischaemia leading to necrosis occurs. This would then allow the passage of luminal bacteria into the local pericolic tissue. With time, this would mature into a local abscess. In cases of failure of local tissue to contain the infection, there may be a progression to a faecal peritonitis. This spectrum of diverticular complications can be classified into the four stages as proposed by Hinchey (Table 15.14.1). More recently, a practical classification based on CT findings has been proposed, which is effectively a modified Hinchey classification (Table 15.14.2). The sigmoid colon, which is less compliant than other colonic segments, is where intraluminal colonic pressures are highest. This reflects the observation that the sigmoid colon is the commonest area in the colon to develop diverticular disease and also sec- ondary complications such as perforation. It has also been noted that diverticula are very distensible and other factors are thought to play a role in whether complications such as perforation occur. Pathology reveals that diverticula consist mainly of a mucosal layer and any factor that results in changes of the integrity of the mu- cosal barrier will result in alteration of the ability microbial popu- lation to pass into the local tissues. This can be divided into factors affecting: • the microbial flora (antibiotics and fibre deficiency) • mucin secretion (nonsteroidal anti-​inflammatory drugs (NSAIDs) and fibre) • epithelial cell insult (NSAIDs) • immune activity in the colonic wall (age, drugs such as cortico- steroids and immunosuppressants) There is a growing body of evidence that NSAIDs have a role to play in complicated diverticular disease. Two prospective case–​control studies have shown patients with complications of diverticular disease were more likely to be taking NSAIDs than age-​matched controls. Another study compared 115 cases with complicated di- verticular disease with 77 with uncomplicated disease. NSAIDs and corticosteroids were found to be associated with development of peritonitis and abscess formation. Also, a large American co- hort study following over 35 000 male health professionals showed that individuals on NSAIDS had a relative risk of 2.2 of developing symptoms of abdominal pain, bleeding, or change in bowel habit secondary to diverticular disease. The action of NSAIDs may be sec- ondary to a reduction in mucosal blood flow as a result of modula- tion of prostaglandin levels. Table 15.14.1  Hinchey classification of sepsis/​contamination in diverticulitis Stage Characteristics I Pericolic abscess II Contained pelvic, retroperitoneal, or distant intraperitoneal abscess III Generalized purulent peritonitis, no communication with bowel lumen IV Generalized faecal peritonitis, communication with bowel lumen Table 15.14.2  Modified Hinchey classification in diverticulitis Stage Characteristics 0 Mild clinical diverticulitis Ia Ib Confined pericolic inflammation—​phlegmon Confined pericolic abscess II Pelvic, or distant intra-​abdominal, or retroperitoneal abscess III Generalized purulent peritonitis IV Faecal peritonitis

section 15  Gastroenterological disorders 2962 Pathology A diverticulum consists of a herniation of mucosa through the co- lonic musculature. As it enlarges, its muscular covering atrophies, so that the fully developed diverticulum consists of mucosa, connective tissue, and peritoneum, making it strictly a false diverticulum. The striking abnormality is in the thickening of the circular and longitu- dinal muscle, which both narrows the colonic lumen and shortens the sigmoid like a concertina to give a ‘sawtooth’ appearance on barium enema. The diverticula occur as slit-​like apertures between the muscle clefts. Inflammation in diverticular disease is the result of infection around diverticula, which spreads within the pericolic fat to form a dissecting abscess. Usually a single diverticulum is the cause of a pericolic abscess, perhaps initiated by the presence of a faecolith. Involvement of the peritoneum results in local peritonitis, which may become generalized in the event of a perforation. This may also give rise to intra-​abdominal abscesses or fistulas to the bladder, small bowel, vagina, or uterus. Repeated episodes of diverticulitis lead to a contracted, narrowed sigmoid colon surrounded by fibrous tissue. Bleeding in diverticular disease can often be traced to an in- fected diverticulum. This may cause either the erosion of a vessel in its wall or the formation of granulation tissue inside the diver- ticulum, which then bleeds. Clinical features, investigation, and management Only 15 to 25% of cases of diverticular disease result in symptoms, of which 75% develop diverticulitis. They are usually discovered in- cidentally. The symptoms usually result from disordered motility ra- ther than secondary complications of the disease. Uncomplicated diverticular disease Symptoms which are attributable to diverticular disease include col- icky abdominal pain and bloating. Pain can be felt along the course of the colon, particularly over the sigmoid, and is often accompanied by a change in bowel habit with the passage of broken, pellety stools after considerable straining. Examination may reveal some tender- ness over the sigmoid colon without guarding or evidence of sys- temic upset. These symptoms may be indistinguishable from those of the irritable bowel syndrome. The passage of blood with an un- formed stool needs to be investigated thoroughly to exclude more sinister pathology. All patients should have a CT colonography or flexible sigmoidos- copy to exclude a rectal or sigmoid carcinoma (Fig. 15.14.1). Once diagnosed, patients should be reassured that there is no serious underlying disease and a high-​fibre diet should be recommended. Exercise and high dietary fibre have been shown to prevent the devel- opment of diverticular disease in prospective studies. However, evi- dence for the efficacy of dietary fibre for the treatment of established diverticular disease is not conclusive, as shown by two random- ized controlled trials where only one showed improved symptoms. Current dietary recommendations include wholemeal bread, whole- wheat breakfast cereals, rough porridge, or muesli, and fresh fruit and vegetables daily. Fibre increases stool bulk in three ways—​by holding water, by proliferation of bacteria, and from the by-​products of bacterial fermentation. The coarser the fibre, the greater is the faecal bulk, but also the greater the unpalatability. Although cooking bran improves its taste, it reduces its water-​holding capacity. A good clinical response is usually achieved by including two tablespoons of bran with the morning cereal, but about one-​half of patients will experience gaseous distension or cramps on starting the high-​fibre diet. It is worth warning them that this is likely to happen and that it will resolve within a month or so if they persist with the diet. More recent studies looking at pharmacological agents have shown some benefit with rifaximin (a derivative of rifamycin), pro- biotics, and fibre. Mesalazine has also been associated with a de- creased recurrence of symptoms over placebo. However, this study also showed that abdominal pain was more common in the treat- ment group. A case–​control study has shown that mesalazine is as- sociated with reduced intracolonic pressure and a reduction in the perforation rate. A reduction in perforation rate was also observed with the use of calcium channel blockers. This is thought to act via the mechanism of reducing intracolonic pressure. Long-​term use of opioids may be detrimental in such patients, resulting in an in- creased risk of developing perforation. In patients with pain, antispasmodics such as mebeverine may be useful. In a minority with repeated severe attacks, an elective laparo- scopic resection might be indicated (Table 15.14.3). This is probably more effective than sigmoid myotomy, an operation that became popular in the mid 1960s. In this procedure, the circular muscle is divided with a longitudinal incision to widen the colonic lumen. The incision is made through the taenia so as to avoid opening diver- ticula, and is deepened until the mucosa is just seen. The operation Table 15.14.3  Indications for surgery in diverticular disease Sepsis Purulent peritonitis Faecal peritonitis Nondrainable pelvic or pericolic abscess Colonic obstruction Inflammatory stricture Fibrotic stricture Suspected malignancy Fistulae Colovesical Colovaginal Ileocolic Major haemorrhage Fig. 15.14.1  Barium enema showing a narrowed sigmoid colon with a few diverticula. This appearance can be confused with that of a carcinoma and colonoscopy would be indicated to clarify the diagnosis.

15.14  Colonic diverticular disease 2963 lowers the sigmoid intraluminal pressures and improves symptoms but, after 3 years, pressures return to their former levels. The use of myotomy has declined and the procedure is now rarely, if ever, performed. The current gold standard is a laparoscopic sigmoid resection. Complicated diverticular disease Complications of diverticular disease include diverticulitis, which can be subdivided into uncomplicated and complicated attacks. The latter subgroup includes patients with pericolic abscess for- mation, peritonitis, fistula formation, intestinal obstruction, and haemorrhage. Complicated diverticular disease results in significant morbidity and mortality. This has obvious cost implications in terms of expend- iture in health services across the Western world. It is important to distinguish the minority of patients who suffer from a febrile attack with left iliac fossa peritonism, sometimes called left-​sided appendi- citis, from those with chronic pain and diarrhoea. The inflammation may settle with minimal symptoms, or develop into a pericolic ab- scess or peritonitis. Clinical assessment alone for the diagnosis of diverticulitis (or its complications) is not precise enough. CT is highly accurate and should be performed. Ultrasonography or MRI can be used as an al- ternative to diagnose acute diverticulitis, with the choice depending mainly on local preferences and experience. There is no role for col- onoscopy in the acute phase. Acute diverticulitis Pain is felt over the left lower abdomen, and the patient may have pyrexia, malaise, anorexia, and nausea which is evidence of sys- temic upset. The neutrophil count and C-​reactive protein level are raised. This is as a result of localized bacterial infection in the colonic wall causing an inflammatory infiltrate thus resulting in systemic manifestations. In some cases, right iliac fossa tender- ness may be present due to sigmoid colon looping to the right side of the abdomen. This may be diagnosed at laparoscopy for right iliac pain. The generally recommended treatment is with rest, antibiotics, usually co-​amoxiclav 1.2 g and metronidazole 500 mg 8-​hourly (ef- fective against Gram-​negative bacteria and anaerobes), and anal- gesia. Most patients with an uncomplicated attack can be treated as outpatients. It is noteworthy, however, that a recent randomized trial showed that antibiotic treatment for acute uncomplicated diverticu- litis did not accelerate recovery, also that antibiotics did not pre- vent complications or recurrence. Regardless of the treatment, most cases settle within a few days and the diagnosis can be confirmed after 6 to 8 weeks with imaging or endoscopy. A narrow segment can sometimes be difficult to distinguish from a carcinoma and any doubtful cases can be clarified by subsequent careful colonoscopy (Fig. 15.14.2). Routine intraluminal imaging following an episode of CT-​ or ultrasonography-​diagnosed acute diverticulitis is recom- mended to exclude the occasional synchronous cancer. If symptoms fail to resolve, or recur, laparoscopic resection of the sigmoid colon may be necessary. When it is necessary to resect an acutely inflamed and unprepared colon, a Hartmann’s operation may be safer than a sigmoid colectomy as the former avoids an anastomosis, although recent studies have shown the feasibility and safety of primary anastomosis in these circumstances. Complications will normally develop during the primary episode, with further episodes having less inflammatory sequelae. The risk of recurrence after the first episode ranges from 7 to 60%. Elective surgery after uncomplicated diverticulitis may be indicated by the presence of persistent symptoms, and the frequency and severity of attacks. It would also be reasonable to discuss surgery in a patient under the age of 50 years presenting with severe, complicated di- verticulitis for the first time. However, this needs to be tempered by the observation from a population-​based study that only 25% of patients with perforated diverticulitis actually had a previous his- tory of diverticular disease. This is in agreement with other studies which puts the range at 3 to 30%. Furthermore, following elective operation, 10% develop recurrent diverticulitis. Patients being con- sented for elective operations therefore need to be fully informed of the potential risks and benefits. Current guidelines do not suggest the routine indication for elective surgery following uncomplicated diverticulitis. There is little evidence to support a different management strategy in younger patients compared to older ones. However, earlier elective surgery might be justified in immunocompromised patients because of an increased risk of complications in this population. For recur- rent diverticulitis operated electively, a primary anastomosis would be ideal. Diverticular abscess Acute diverticulitis can lead to a local peritonitis with abscess forma- tion, either in the paracolic or pelvic area. There may be a palpable mass and a swinging fever. When in doubt, the diagnosis should be confirmed by spiral CT scanning with rectal contrast (Fig. 15.14.3). The latter investigation is excellent at demonstrating bowel wall thickening, abscess formation, and extraluminal disease. The speci- ficity is high (>97%). The size of the abscess can be measured. Small abscesses less than 5 cm in size can be treated with antibiotics with good outcome. Those less than 2 cm in size can be treated with anti- biotics in the community. It is wise to let an abscess localize while treating the patient with rest, antibiotics, and analgesia. Some abscesses will be amenable to Fig. 15.14.2  The typical appearance of diverticula seen at colonoscopy. Note the muscular haustra and the mouths of diverticula—​one with a faecolith. From the Slide atlas of gastroenterology, Gower Medical Publishing, London, with permission.

section 15  Gastroenterological disorders 2964 drainage by direct incision, either over them or via the rectum or va- gina. More complicated collections, especially in the pelvis, are best drained by CT-​guided aspiration or drain placement. There is rarely any need to do a proximal transverse colostomy. If drainage persists, an elective laparoscopic sigmoid colectomy with primary anasto- mosis can be done at a later date. Even when an abscess is localized, there is a risk of rupture into the peritoneal cavity with subsequent generalized peritonitis. Perforated diverticulitis Acute diverticulitis can be complicated by generalized purulent peri- tonitis, either by direct spread from the inflamed colon or by rupture of a peridiverticular abscess. Purulent peritonitis carries a mortality of around 15%. The clinical picture is of severe intraperitoneal sepsis with toxaemia, ileus, and abdominal pain, and generalized sepsis will often follow. Before surgery, such patients need to be intensively resuscitated with intravenous fluids together with administration of systemic antibiotics. Once stabilized, they require emergency laparotomy. Other causes of the acute abdomen that may not require surgery should be excluded, including pelvic inflammatory disease, ureteric calculus, and even pulmonary embolus. In these circumstances, spiral CT scanning is invaluable. Surgical options include: • laparoscopic lavage with drainage • defunctioning transverse loop colostomy • Hartmann’s procedure—​removing the diseased sigmoid, over- sewing the distal rectum, and bringing out an end colostomy • colonic resection and primary anastomosis Laparoscopic washout has been shown to be an effective option in selected cases where there is no evidence of widespread faecal con- tamination, but its use remains controversial. Drains are routinely left in place at the end of the procedure. An elective laparoscopic sigmoid resection is advised at least 12 weeks after the initial attack. Defunctioning stomas are associated with complications of ongoing sepsis secondary to residual faecal material that is still pre- sent within the septic colon. Historically, complicated diverticular disease was managed in three stages in which initially the sepsis was drained together with the formation of transverse loop colostomy. This was then followed by resection of the diseased segment and end colostomy followed by reversal. However, this required three hospital admissions and resulted in considerable morbidity. The reduction to a two-​stage (Hartmann’s) procedure resulted in a drop in mortality rates. More recent studies suggest that in a selected case group a one-​ stage process involving primary anastomosis is not associated with increased mortality rates. This has the added advantages of reducing hospital readmissions, although there is a risk of potential leak, and most patients with a primary anastomosis require a defunctioning ileostomy There has been a shift away from the more conservative procedures in this situation due to the residual ‘septic colon’ and the further problem of the unsuspected carcinoma within the inflam- matory mass. For these reasons, experienced colorectal surgeons tend to perform colonic resections. Hartmann’s operation is still the procedure most frequently used (Fig. 15.14.4). Hartmann’s procedure is safe and effective and removes the postoperative risk of anastomotic leak, although subsequent (a) (b) Fig. 15.14.4  (a) The area of sigmoid colon resected for perforated diverticular disease. (b) Hartmann’s operation—​the sigmoid colon has been resected, the rectum oversewn, and a left iliac fossa colostomy fashioned. Fig. 15.14.3  CT of the pelvis in a patient with acute diverticulitis. The sigmoid colon is grossly thickened, the lumen narrowed, and pockets of air are seen in the diverticular disease.

15.14  Colonic diverticular disease 2965 reconnection involves a major operation in older patients. A signifi- cant proportion of patients (up to 40%) do not undergo reversal, thus adding weight to the argument for the one-​stage procedure in selected and stable cases. Faecal peritonitis This is a catastrophic complication with a mortality approaching 50% in patients over the age of 80 years. A diverticulum ruptures, often with little or no inflammation, liberating quantities of faeces into the peritoneal cavity. Rapid and severe septic shock ensues. Energetic resuscitation is necessary, followed promptly by sur- gery and a Hartmann’s operation. These patients often need to be stabilized in an intensive care unit postoperatively. Intestinal obstruction Recurrent inflammation with fibrosis and muscular hypertrophy can lead to progressive stenosis and colonic obstruction, which is usually chronic but may present acutely. Conservative treatment is worth trying at first, provided a carcinoma has been excluded. With the aid of a stool softener, the symptoms may resolve and the stric- ture gradually dilate. If these measures fail, the bowel should be prepared for a laparoscopic segmental colonic resection, with care taken not to aggravate the obstruction. A surgical resection is also indicated if a carcinoma cannot be excluded. Small-​bowel obstruction is sometimes a complication of acute diverticulitis, as the bowel may adhere to the inflammatory mass. It usually resolves as the inflammation subsides but on occasion, surgery is required for division of adhesions or even a small-​bowel resection. Colonic fistulas A colovesical fistula usually presents with recurrent urinary tract in- fections, together with pneumaturia or faecuria. The fistula arises in the sigmoid, which has often folded over into the pouch of Douglas, and adheres to the apex of the bladder. This is the most frequent cause of colovesical fistula, but carcinoma and Crohn’s disease should be excluded. In women, this condition is usually seen after hysterectomy. Fistulas may also occur between the sigmoid and vagina, uterus, ureter, and ileum. They seldom heal spontaneously but do not always give rise to disabling symptoms and so represent a relative indication for surgery. Sigmoid colectomy as a one-​stage procedure is the best option, and colostomy is rarely required. A fistula into the bladder is simply closed. Urethral catheter drainage is continued for a week, and can be removed after a cystogram has excluded a urinary leak. Haemorrhage Major haemorrhage is an uncommon but well-​recognized compli- cation. Bleeding from the colon only accounts for 20% of gastro- intestinal haemorrhages, of which 50% are diverticular in origin. It is important that other more common causes for bleeding such as polyps and angiodysplasia are excluded by angiographic studies or CT angiography and colonoscopy. Most patients tend to be eld- erly. Massive bleeding is defined when over 40% of blood volume is lost. This can be catastrophic in older patients who have a reduced physiological capacity to maintain vital organ perfusions. Massive bleeds tend to present as fresh rectal bleeding. Up to 80% will settle down spontaneously and require only transfusion and supportive measures. The initial management of these patients in- cludes oxygen therapy with adequate venous access. Disorders of coagulation need to be identified and corrected during the ongoing resuscitation process. It is important to exclude upper gastrointes- tinal bleeding by way of endoscopy. Colonoscopy in the immediate aftermath of a bleed can be difficult but in experienced hands the diagnostic yield can be high as 70%. The endoscope needs to have a wide-​bore suction channel and excessive insufflation needs to be avoided due to the risk of causing a rebleed. In units with access to vascular services, mesenteric angiography can be performed. An ongoing minimum bleeding rate of 1 to 1.5 ml/​min is required to accurately localize the lesion. Therapeutic interventions that are available include vasopressin injection and selective embolization, though this carries a risk of colonic ischaemia. Radiolabelling is usually reserved for patients who are haemo- dynamically stable, with no access to vascular radiology and failure to establish a diagnosis during endoscopy. However, in circum- stances where there is accelerated transit of blood, localization can be poor. As the haemorrhage can be from any part of the colon, good localization is an essential prelude to any operation. Blind colonic resections have a particularly poor record and if the site of bleeding has still not been located, on-​table colonic lavage via the appendix stump and intraoperative colonoscopy will usually target the bleeding segment. A study published in The New England Journal of Medicine re- ported the results of urgent colonoscopy in bleeding diverticular disease. Instead of the traditional conservative measures, pa- tients were given bowel preparation and colonoscoped within 12 h. Bleeding sites thus identified were treated by colonoscopic diathermy and the number of major bleeds, blood transfusions, and operations was reduced together with length of hospital stay. It remains to be seen whether this will result in a major shift of emphasis in management. However, the main objective in these patients should be proper monitoring and prompt investigation after admission with colonic bleeding. FURTHER READING Angenete E, et al. (2014). 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