[Tumours of the large bowel and rectum: possibilities and limitations of sonographic evaluation]

Sonographic detection rate of colorectal tumours in comparison with endoscopy.

Within a period of 32 months all sonographically detected colorectal tumours were registered and the results compared with endoscopic findings within the same period. The patients had no peroral preparation for the sonographic examination which was always performed before coloscopy.

The study encloses 521 tumours in 417 patients. The tumours can be subdivided into 181 cancers, 122 polyps > or = 1 cm, 207 polyps < 1 cm and 11 other tumours. 62 % (112/181) of cancers could be detected by sonography, 30 % of stage pTis, pT1 or pT2, 82 % of stage pT3 or pT4. The detection rate was 20 % for polyps > or = 1 cm, but only 2 % for polyps < 1 cm. The majority of larger tumours not detected on sonography (15/18) was located in the rectum and lower sigmoid colon.

Colorectal cancers of stage T3 and T4 can be detected sonographically in a high percentage of cases. Sonography provides insufficient results in detecting polyps and small cancers, and even larger tumours may be missed especially in the lower sigmoid colon and rectum.