[Transurethral ultrasonography for the preoperative staging of prostatic cancer]

Transurethral ultrasonography was used to demonstrate the local extension of prostatic cancer in 18 patients undergoing radical prostatectomy. By ultrasonography, capsular penetration of the carcinoma was judged from irregularity and protrusion of the capsule. Infiltration to the seminal vesicle was determined by asymmetry on the echogram. The ultrasound staging was compared to the pathological findings of the step sectioned specimens obtained by total prostatectomy. The accuracy of transurethral ultrasonography in demonstrating the local extension was 94%. The accuracy rates in detecting capsular penetration and depicting seminal vesicle infiltration were 94% and 72%, respectively. The local extension of prostatic cancer has been evaluated by transrectal and transabdominal scannings. Ultrasonography is considered to be more reliable than digital rectal examination, CT or MRI in the preoperative staging of the prostatic cancer. The present study revealed that transurethral ultrasonography had advantage in demonstrating the capsule of the prostate for the following reasons; 1) there is no interposing tissue between the probe and prostate because the probe is inserted into the prostatic urethra, 2) the prostate is observed without deformity caused by the balloon in the rectum, and 3) the beam hits the capsule perpendicularly. The prostatic cancer at the portion of capsular penetration was hypoechoic or anechoic pathologically, these areas corresponded to homogeneous and large cancer nodules. Transurethral ultrasonography is valuable in demonstrating local extension of the prostatic cancer, in particular capsular penetration.