Diagnostic approach to the patient with a chronic diarrheal disorder

Chronic diarrhea is a common problem facing the practitioner of medicine. Despite impressive advances in diagnostic technology, many patients continue to have chronic diarrhea without a firm diagnosis being established. Most important, the history and physical examination are often perfunctory and the patient undergoes a number of contrast and imaging studies, endoscopic procedures, and laboratory investigations which may still be non-diagnostic. In all patients with chronic diarrhea, which I will arbitrarily define as diarrhea that has persisted over at least 2 months, there is a need for a careful orderly approach to the differential diagnosis. In this paper I will detail a method that I have used in evaluating such patients. The method emphasizes a careful history and physical examination, judicious and sequential use of laboratory investigations, contrast studies, and endoscopic procedures, and calls attention to special situations where more detailed investigations are required. I have found that unless I go through this detailed diagnostic approach, I will miss disorders that can be readily diagnosed and, more importantly, such patients may not be given appropriate treatment.