Incidental finding of rectal carcinoma during transrectal US for prostatic diseases.

During transrectal ultrasound (TRUS), rectal carcinoma was an incidental finding in seven patients among a series of 5,000 TRUS examinations. TRUS was performed in seven patients with symptoms characteristic of prostatic diseases. All seven patients underwent examination by at least one physician before TRUS and, except for abnormal prostatic findings, no tumors were detected during digital rectal examination (DRE). The tumors were clearly visualized with TRUS and were easily palpated during DREs performed after TRUS. They were large and were located mainly along the posterior and lateral walls of the rectum. All the tumors were diagnosed by means of proctoscopy; the biopsy findings were positive, and the pathologic staging indicated advanced disease: adenocarcinoma of the rectum with a minimum grade of Dukes C. It is recommended that, in addition to evaluation of scans obtained in the transverse plane, the multiplane transducer be used to evaluate the longitudinal plane of the rectum for detection of possible undiscovered tumors.