Sonographic features of colonic Crohn's disease: comparison of in vivo and in vitro studies.

The entire length of the colon, starting at the recto-sigmoid junction and ending at the cecum, can be sonographically visualized by retrograde water instillation into the colon. In order to evaluate the validity of colonic sonography as a diagnostic method, in vivo transabdominal ultrasound examination of the colon wall after water insufflation was compared with in vitro ultrasound examination of the same colon wall on four resected surgical specimens from patients with colonic Crohn's disease and four controls. The normal colon wall specimens were easy to recognize in that they had a thickness of 4 mm and five layers of different echo patterns, which could be demonstrated both in vivo and in vitro. On the other hand, in patients with Crohn's disease, a distinct wall thickening of up to 1.5 cm was found, and the typical five-layer stratification could no longer be recognized. The sonographic changes demonstrated in vivo and in vitro were thus comparable both in wall thickness and wall structural alterations. This study shows that transabdominal colonic sonography of the fluid-filled colon is a diagnostic method that permits a detailed and accurate assessment of the normal and the pathologically changed colonic wall.