[Effect of an enema on the macroscopic and microscopic appearance of the rectal mucosa]

In flexible fiberoptic sigmoidoscopy the application of an enema is mandatory. By contrast, rigid sigmoidoscopy can be performed without preparation. In 16 patients we tested the influence of a hypertonic enema on the macroscopic and microscopic appearance of the rectal mucosa. As a first step in the unprepared patient the mucosa was assessed and a rectal biopsy obtained. After enema this procedure was repeated. Development of mucosal edema was observed, although the histopathologist was not always able to decide whether or not the biopsy was taken before or after the enema. Histological assessment of edema requires histometric measurements which cannot be obtained from biopsy specimens. A knowledge of these changes is particularly important in assessment of inflammatory bowel disease, where edema of the unprepared mucosa means slight proctitis, and we recommend that the histopathologist be informed if enemas are used for bowel preparation.