Staging of rectal carcinoma: prospective comparison of endorectal US and CT.

One hundred two consecutive patients undergoing surgical treatment for rectal cancer were examined by means of endorectal ultrasound (US) for staging before surgery. Eighty-one of these patients also underwent staging with computed tomography (CT). The diagnostic sensitivity of endorectal US in detection of tumor extension into fat was 67%; specificity, 77%; positive predictive value, 73%; and negative predictive value, 72%. The sensitivity of CT for this finding was 53%; specificity, 53%; positive predictive value, 56%; and negative predictive value, 50%. The sensitivity of endorectal US in detection of lymph node infiltration was 50%; specificity, 92%; positive predictive value, 68%; and negative predictive value, 84%. For this finding the sensitivity and negative predictive value, 76%. These findings suggest that endorectal US may be as accurate as CT, or more so, in the preoperative staging of rectal cancer.