Objectives: The entire length of the colon, starting at the rectosigmoid junction and ending at the cecum, can be visualized by transabdominal sonography after retrograde water instillation into the colon. By this method, termed hydrocolonic sonography, it is possible to evaluate in detail the lumen, the colon wall, and the surrounding tissue. Five layers of different echogenicity can be differentiated within the colon wall.
Methods: In a prospective study of 440 patients, we compared the value of conventional abdominal sonography and hydrocolonic sonography with that of colonoscopy, in the diagnosis and differential diagnosis of ulcerative colitis and colonic Crohn's disease.
Results: In 93% of patients with Crohn's disease, the normal five-layer structure of the colonic wall was no longer in evidence, and the wall appeared hypoechogenic and clearly thickened. In contrast, in patients with ulcerative colitis, the five-layer structure could clearly be discerned, and although the colon wall remained hypoechogenic, it was only moderately thickened. Colonic Crohn's disease and ulcerative colitis were detectable by hydrocolonic sonography, with a sensitivity of 96% and 91%, respectively, whereas the sensitivity achieved by conventional abdominal sonography was only 71% and 62%, respectively. Furthermore, hydrocolonic sonography made possible the differentiation of Crohn's disease from ulcerative colitis in 93% of the cases.
Conclusion: This new diagnostic procedure could thus advantageously be introduced for the diagnosis, differential diagnosis, and follow-up of patients with chronic inflammatory large bowel diseases.