Objective: To evaluate the effect of a transrectal probe on the opening of internal urethral sphincter.

Method: Twenty-five patients with a neurogenic bladder dysfunction were included in this study. For the transrectal ultrasonography (TRUS), a transrectal probe was inserted into the rectum before the bladder was filled. Internal urethral sphincter opening was investigated during the filling and voiding phases. The bladder was emptied and the probe was introduced intrarectally after the bladder filling for the investigation of internal urethral sphincter opening. Twelve subjects underwent an additional cystometry for the recording of maximal intravesical pressure with and without transrectal probe.

Results: There was no significant difference in the sensitivity of TRUS for the opening of internal urethral sphincter with insertion of the probe before or after the bladder filling. There was no significant change of the maximal intravesical pressure with or without the probe in the rectum.

Conclusion: The results demonstrate that transrectal probe for TRUS does not cause a reflex effect on the opening of internal urethral sphincter.

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.