Objective: To compare the sensitivity of transrectal ultrasonography (TRUS) and voiding cystourethrography (VCUG) in assessing the opening of bladder neck and external urethral sphincter during the filling phase and voiding phase.

Method: TRUS and VCUG were performed for visualizing the opening of bladder neck and external sphincter in 36 patients with a neurogenic bladder dysfunction and the sensitivity of two techniques was compared. The finding was considered to be a true positive when the opening of internal or external sphincter was visualized on either one of TRUS or VCUG.

Results: The sensitivity of TRUS was significantly higher than VCUG in visualizing the opening of bladder neck during the filling phase. However, there was no significant difference in the sensitivity of two techniques for the opening of external sphincter during filling phase or the opening of internal and external sphincters during voiding phase.

Conclusion: The results demonstrate that the TRUS provides a satisfactory information and can be an alternative method to the radiological VCUG in visualizing the opening of bladder neck or external sphincter.