What is the preferred endoscopic procedure for the evaluation of diarrhea in AIDS?
The advantage of endoscopy is that it permits direct visualization of the mucosa and retrieval of tissue for histologic examination. The diagnostic yield of colonoscopy in HIV-infected patients with chronic diarrhea and negative stool studies ranges from 27% to 37%; in patients with AIDS, CMV is the most common etiologic factor identified.
CMV colitis is usually present in the distal colon; however, isolated, right-sided CMV colitis has been reported. Therefore if CMV is suspected as the cause of diarrhea, a full colonoscopy is warranted, especially if sigmoidoscopy is negative. However, it is still not clear whether colonoscopy has a higher yield than flexible sigmoidoscopy for the detection of organisms other than CMV. Evaluation with colonoscopy is prudent if right-sided abdominal complaints are also reported.
The value of upper endoscopy and small bowel biopsy in the evaluation of chronic diarrhea has also been demonstrated, although specific treatment options for most small bowel pathogens are limited. Some would obtain ileal biopsy at the time of colonoscopy rather than proceed with upper endoscopy and biopsy. The most commonly detected organisms involving the small bowel are cryptosporidia and microsporidia.