Evaluation of chronic diarrhea in patients with human immunodeficiency virus infection.

Chronic diarrhea is a common problem for patients with human immunodeficiency virus infection, especially those with advanced disease. The extent of evaluation and whether to do flexible sigmoidoscopy, colonoscopy, and/or upper endoscopy have been areas of significant debate. Based upon the marked improvement in long-term survival since the introduction of highly active antiretroviral therapy, a comprehensive evaluation is currently justified. A stepwise approach to the evaluation of chronic diarrhea appears to be the best approach. The first step is a history, with a focus on any association between the onset of diarrhea and the institution of protease inhibitor therapy, which is associated with significant diarrhea in many patients. If there is no temporal association with antiretroviral therapy, the next step is examination of stool for bacterial and protozoal pathogens. If the stool studies are negative, the next step is to proceed to colonoscopy. Flexible sigmoidoscopy alone has been noted to miss up to 39% of cases of cytomegalovirus colitis. The inclusion of ileoscopy and biopsy of the terminal ileum during colonoscopy has a significant yield for microsporidiosis, which may obviate the need for upper endoscopy. The highest yield can be expected in patients with fever, weight loss, and a CD4 count of under 200 cells/mm3, especially those with a CD4 count less than 50 cells/mm3.