Irritable Bowel Syndrome Message Boards | On the Relationship Between Colon Ischemia, Irritable Bowel Syndrome, and Serotonergic Therapy of Irritable Bowel Syndrome

From Medscape Gastroenterology

Irritable Bowel Syndrome Expert Column
On the Relationship Between Colon Ischemia, Irritable Bowel Syndrome, and Serotonergic Therapy of Irritable Bowel Syndrome
Posted 09/24/2004

Lawrence J. Brandt, MD

Introduction and Context
The Problem
Colon ischemia and irritable bowel syndrome (IBS) are 2 common gastroenterologic disorders that, until recently, were thought to occur independently in very different populations. We know now, however, that there is a complex association between the 2: (1) colon ischemia appears to be more common in the IBS patient than was recognized previously; and (2) there is concern that the newly developed serotonin receptor agonists or antagonists may increase the risk of colon ischemia, and serotonergic signaling may be abnormal in patients with colitis. This review highlights some of the relationships between colon ischemia, IBS, and therapy for IBS.

IBS -- Pathophysiology and Clinical Presentation
IBS is a disorder that is diagnosed by various symptom-based criteria, such as the Manning, Rome, and Rome II criteria. IBS lacks any biologic, physiologic, structural, or serologic marker, and so diagnosis is symptom-based. Symptoms typically include abdominal discomfort or pain, bloating, diarrhea, fecal urgency, and constipation. Symptoms may change with time, and patients who have diarrhea or constipation as a major part of their illness may evolve to the opposite bowel habit or develop a pattern in which they alternate between the 2. IBS must never be considered as the explanation for rectal bleeding, bloody diarrhea, weight loss, fever, constitutional symptoms, or anemia, and in the presence of these "alarm" symptoms or signs, organic disease must be excluded using conventional stool tests, endoscopic, and radiologic examinations. For the IBS patient without alarm symptoms, the routine use of these tests is not recommended, although for patients with IBS and diarrhea, serologic testing for celiac sprue may be appropriate and cost-effective.[1,2] Of course, screening tests for colon cancer are recommended for all patients 50 years of age or older, including those with IBS.

Colon Ischemia -- Pathophysiology and Clinical Presentation
Colon ischemia generally presents in individuals older than 55 years, a population considerably older than that typically affected by IBS. The known causes of colon ischemia are many, but in the usual case, no definitive cause is found; most episodes of colon ischemia are thought to be caused by brief periods of localized nonocclusive ischemia. The acute onset of mild, lower abdominal pain accompanied or followed by diarrhea, rectal bleeding, or bloody diarrhea is typical. Most patients with colon ischemia have spontaneous resolution of symptoms within several days. Computed tomography of the abdomen usually shows segmental thickening of the colon, although this is not a specific finding. Colonoscopy, if performed within the first 24-48 hours, usually will show submucosal hemorrhage or edema in a segmental pattern (ischemic colopathy). If the examination is repeated within a few days after the onset of symptoms, it will show the disease process to have evolved into a segmental (ischemic) colitis pattern with ulceration and even pseudopolyp formation, an appearance that may mimic inflammatory bowel disease or infectious colitis; biopsy usually is nonspecific, with only infarction and ghost cells pathognomonic of ischemic injury. In general, mesenteric angiography is not used to evaluate patients suspected of having colon ischemia, because by the time of presentation, colonic blood flow usually has normalized.

It is important for primary care practitioners to be aware of colon ischemia because it is a common cause of bloody diarrhea in the elderly and can be seen in patients of all ages, especially those who have a coagulation disorder, systemic illness associated with vasculitis, or those with IBS. Moreover, colon ischemia can mimic or be mimicked by infectious colitis or inflammatory bowel disease. Most patients who develop colon ischemia do well with conservative management. For the patient who continues to have symptoms for more than 2 weeks, referral to a gastroenterologist is recommended because it is likely that these individuals will have a complicated course.

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Section 1 of 6 Next Page: Issues in Epidemiology

Lawrence J. Brandt, MD, Chief of Gastroenterology, Montefiore Medical Center, Bronx, New York; Professor of Medicine and Surgery, Albert Einstein College of Medicine, Bronx, New York

Disclosure: Lawrence J. Brandt, MD, has served as an advisor or consultant for Novartis, GlaxoSmithKline, Solvay, and TAP. He has also disclosed he is on the speakers bureau for AstraZeneca.

Medscape Gastroenterology 6(2), 2004. � 2004 Medscape

Continue reading this article here http://www.medscape.com/viewarticle/488174_2

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