Irritable bowel syndrome diagnosis

Agrawal A and Whorwell PJ (2006) Irritable bowel syndrome diagnosis and management. British Medical journal 332 280-283. 

A 55-year-old man with irritable bowel syndrome who took alosetron 1 mg bd for 4 days developed symptoms of ischemic colitis, including rectal bleeding, and the diagnosis was confirmed macroscopically and histologically at colonoscopy. The symptoms suggestive of colitis abated on withdrawal of alosetron, but the symptoms of irritable bowel syndrome returned. Colonoscopy 2 weeks later showed a normal colon and biopsies showed normal colonic histology. 

FIGURE 36-2. Recommendations for treating chronic diarrhea. Follow these steps (1) Perform a careful history and physical examination. (2) The possible causes of chronic diarrhea are many. These can be classified into intestinal infections (bacterial or protozoal), inflammatory disease (Crohn s disease or ulcerative colitis), malabsorption (lactose intolerance), secretory hormonal tumor (intestinal carcinoid tumor or VIPoma), drug (antacid), factitious (laxative abuse), or motility disturbance (diabetes mellitus, irritable bowel syndrome, or hyperthyroidism). (3) If the diagnosis is uncertain, selected appropriate diagnostic studies should be ordered. (4) Once diagnosed, treatment is planned for the underlying cause with symptomatic antidiarrheal therapy. (5) If no specific cause can be identified, symptomatic therapy is prescribed. 

The condition of irritable bowel syndrome (IBS) is just that, a "syndrome." It is not truly a diagnosis. It is a set of symptoms and signs indicating some commonality. The most likely cause concerns the effects of the autonomic system. The sympathetic and parasympathetic systems are not... 

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