[What is the contribution of echography in Crohn disease?].

The alimentary tract often contains some gas which may obstruct the passage of the ultrasonic beam. However, when a pathological process involves the intestinal wall, a "target" pattern or a "pseudo-kidney" pattern may be visualized by ultrasound. It is also possible to visualize by US examination some complications of Crohn's disease: intestinal obstructive lesion with distended loops, fistula, abscesses and renal or biliary lithiasis. Because sonography is non-invasive and simple to perform without radiation exposure, it should often be used in Crohn's disease as the initial diagnosis and as the following-up test.