RESUMEN
OBJECTIVE: To explore the possibility of injury to the striated urethral sphincter by incision to the anterior lobe region in transurethral prostatectomy. METHODS: We incised the anterior lobe region of 60 patients with benign prostatic hyperplasia (BPH) undergoing transurethral prostatectomy. The patients were divided into four groups according to the incision fields: proximate superficial (group 1), proximate deep (group 2), distal superficial (group 3) and distal deep (group 4). The tissues taken from the anterior lobe region were subjected to HE staining, and the smooth and striated muscles were detected by immunohistochemical identification of smooth muscle actin (SMA) and myoglobin (MYO) in the tissues. The prostate volume, age, and PSA level of the patients were analyzed against their positive or negative results. The relative contents of the striated muscle were compared among groups 2, 3 and 4. The independent-sample between-group t-test was used for statistic analysis. RESULTS: The urethral rhabdosphincter was found in the anterior lobe region, with the smooth muscle intermixed with the striated muscle. The incision injury of the urethral rhabdosphincter was associated with the prostate volume. Increased urethral rhabdosphincter was observed in the anterior lobe region, approaching the apex of the prostate and extending to the urethral lumen. CONCLUSION: The anterior lobe region should not be excessively incised in transurethral prostatectomy so as to avoid direct injury of the striated urethral sphincter, which is especially important for prostates of smaller volume or operation near the apex of the prostate.