Transrectal ultrasonography and operative selection for early carcinoma of the rectum

Transrectal ultrasonography (TRUS) supplements clinical evaluation of early carcinoma of the rectum in selecting patients for local operative therapy, such as transanal excision (TAE).

This study was done to evaluate the accuracy of ultrasonographic staging of tumor depth (T stage) in patients with suspected early carcinoma of the rectum, to compare ultrasonographic with clinical T-staging accuracies within this patient group, to determine if any specific tumor characteristics (configuration, size, location) predispose toward ultrasonographic T-staging inaccuracy, and to examine the role of TRUS in operative selection for patients with early carcinoma of the rectum.

Between April 1990 and December 1992, 62 patients with primary carcinoma of the rectum underwent ultrasonographic staging (uT), whereby three uT4, 27 uT3, 24 uT2 and eight uT1 carcinomas were identified. Of the 32 patients with suspected intramural (uT1 or uT2) disease, 27 underwent prompt operative excision or resection at our institution, allowing comparative histopathologic staging. In this highly selected patient subset, uT1 staging was correct in all instances; uT2 staging was incorrect in 45 percent of instances, with 30 percent having unpredicted transmural penetration. Ultrasonographic and clinical staging accuracies were quantitatively similar, and no tumor characteristics were consistently associated with ultrasonographic imprecision.

Among patients with clinically suspected early carcinoma of the rectum, the decision to perform TAE is supported by ultrasonographic T1 staging. By contrast, the decision to perform TAE cannot be based solely on ultrasonographic T2 staging, because of the possibility for transmural penetration of tumor.