Small intestinal mucosal biopsy for investigation of diarrhea and malabsorption in adults.

The use of small intestinal biopsy for diagnosis in diarrhea and suspected malabsorption depends on an optimal interaction between the clinician-endoscopist and the pathologist. This necessitates open and interactive communication between involved physicians and an appreciation for correct tissue handling and biopsy orientation in the endoscopy unit and the pathology laboratory. Classification of biopsy changes on the basis of architectural abnormalities in the small intestinal biopsy may be helpful in defining the diagnosis and include severe (flat) or variably severe (mild or moderate) abnormalities. For some small intestinal disorders that are characterized by diarrhea or malabsorption, the biopsy findings may be distinctive and lead to a specific diagnosis. For others, like celiac disease, the changes are less specific, and it has become better recognized that an increasing number of conditions can produce similar histopathologic changes. Definition of typical gluten-sensitive biopsy changes in this disorder is critical.