Incidental discovery of ano-rectal disease during transrectal ultrasound performed for prostatic disease

Transrectal ultrasound (US) has long been a routine investigation for the study of various diseases of the prostate. The use of 360 degrees transverse scanning probes and recently, of 3D probes, has been proposed as a suitable means of studying the rectal wall. Between January 1997 and February 2004, 3758 subjects suffering from lower urinary tract symptoms associated with micturition disturbances underwent transrectal ultrasound (TRUS) with a multiplane probe having a variable frequency ranging up to 7.5 MHz and, in the later period, with a transrectal 3D volumetric probe. In 489 patients (13%) TRUS yielded suspicious images of the rectal wall. This finding was verified by a proctologic and rectoscopic examination. In 132 cases (27%) it was shown to be a false positive, mainly due to imperfect cleansing of the anal canal; in 284 cases (58%) benign disease was demonstrated (hemorrhoids in 192 patients, abscesses in 21, perianal fistulas in 18, inflamed lymph nodes in 27, polyps in 16). In 34 patients (7%) a malignant tumor was found (infiltration of the anterior rectal wall by a prostatic adenocarcinoma in 13, and a primitive adenocarcinoma of rectal origin in the remaining 21). It can be concluded that transrectal US does not permit a certain diagnosis of the nature of rectal disease, but does raise a diagnostic suspicion that can orient the surgeon to schedule more invasive diagnostic investigations.