Non-infective colitides

Non-infective colitides

Diverticular colitis Diverticular colitis is a clinicopathological entity distinct from acute diverticulitis (see Diverticular disease ). The term refers to colonic mucosal inflammation, resembling IBD, in a segment of colon a ff ected by diverticula. Symptoms of diarrhoea, pain and bleeding may occur, and the histology overlaps with that of IBD. It is usually self-limiting, with a short clinical course and low rate of recurrence. It is important to di ff erentiate diver ticular colitis from IBD to avoid further unnecessary tests and treatment. Localisation near to diverticula, a previous history of diverticulitis and rectal sparing should raise suspicion. Diversion colitis Diversion colitis is an iatrogenic process that occurs when a colon/rectum is defunctioned with a proximal stoma. Although the majority of patients with defunctioned bowel will develop typical changes of di ff use inflammation with friable mucosa and spontaneous bleeding, less than 50% will develop symp toms of lower abdominal pain, blood and mucus per rectum. The aetiology is likely to be multifactorial with alteration of the bacterial flora and a reduction in the bioavailability of short chain fatty acids (the predominant metabolic substrate of colonic m ucosa). Diagnosis is by endoscopy and treatment includes reassurance and, if feasible, restoration of the bowel continuity . See Chapter 75 . - Radiation colitis Radiation colitis refers to the characteristic acute and chronic morphological changes that occur following radiation treat - ment. Although most commonly occurring in the rectum (proctitis) these changes can a ff ect the colon if any portion falls within the radiation field. Acute inflammatory changes manifest a few days to 6 weeks after treatment, whereas chronic colonic changes leading to fibrosis and stenosis occur up to y ears later. Obstructive symptoms require appropriate radio - - logical and possibly endoscopic assessment and may lead to - resectional surgery . After resection care must be taken to ensure healthy non-irradiated bowel is used for any anastomosis. As - the rectum is the most commonly a ff ected part of the lar ge bowel, further details are given in Chapter 79 . Graft-versus-host disease colitis Graft-versus-host disease colitis (GVHD) is a common compli - cation occurring about 3–6 weeks after haematopoietic stem cell transplantation and is the result of severe immune-mediated toxicity against host cells. The patient develops diarrhoea and vomiting with colicky abdominal pain. Inflammation is e vident on endoscopy . Treatment is complex and di ffi cult. Once established the prognosis is poor. Drug-induced colitis A wide range of medications may induce colitis ( Summary box 77.10 ) and recognition is essential as cessation of the medication often leads to prompt resolution of symptoms. Patients with the DPYD ( dihydropyrimidine dehydrogenase ) gene mutation are particularly prone to colitis if treated with 5-FU during treatment for colon cancer. Dose reduction should be employed. Summary box 77.10 Drugs that may result in colitis /uni25CF /uni25CF - /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF - Ischaemic colitis Ischaemia of the colon typically results from thrombosis or embolism. Sudden embolic events leading to acutely ischaemic bowel present with severe pain out of proportion to the degree of peritonism, bloody diarrhoea, haemodynamic instability and shock. Resuscitation and laparotomy are required with

Non-steroidal anti-in /f_l ammatory drugs Proton pump inhibitors and H2 antagonists Cardiac drugs (digoxin, diuretics, dopamine) Immunosuppressants Antibiotics (owing to increasing the likelihood of C. dif /f_i cile infection) Statins Chemotherapy Antidepressants (selective serotonin reuptake inhibitors) Anti-migraine drugs (ergotamine) Cocaine

bowel ends. Mortality is extremely high. Thrombotic occlusion usually occurs in the context of global atherosclerosis. The presentation of this ischaemic coli tis tends to be less dramatic with abdominal pain, a raised white cell count and rectal bleeding. A plain abdominal radiograph may show ‘thumb-printing’ and endoscop y may demonstrate haemorrhagic oedema. The left colon and, in particular, the splenic flexure are usually the w orst a ff ected (the ‘watershed’ area of blood flow). Symptoms usually settle spontaneously . In some cases, ulceration at the splenic flexure associated with ischaemic colitis may heal with stricturing and present with subsequent large bowel obstruction. Bowel ischemia is a well-known but uncommon complica tion following both open and endovascular abdominal aortic aneurysm repair due to sacrifice of the inferior mesenteric artery .