[Study of directional differences on static and stress urethral pressure profiles of female urethra]

We investigated the female continence mechanisms by comparing directional differences of static and stress urethral pressure profiles (UPP) in urinary continent females with those in stress incontinent females. Also, the mechanisms of bladder neck suspension were investigated by comparing directional differences of UPP pre- and post-operatively.

UPP at rest and under stress were recorded by means of double lumens microtip transducer catheter in 21 females without urinary incontinence (normal group) and 38 females with stress urinary incontinence (SUI group). And UPP were recorded pre- and postoperatively in 19-females of SUI group who had surgical cure of SUI (ope group). These measurements were performed on the urethral directions (anterior-direction of symphysis pubis, lateral and posterior) to which the pressure sensor in the catheter were pointed. Pressure transmission ratios (PTR) were calculated in each quartile dividing functional urethral length (FUL) into four equal lengths. We compared the parameters (the maximum urethral closure pressure = MUCP, FUL and PTR) when the sensor lies at the anterior, lateral and posterior direction in each group. The parameters in normal group were compared with those in SUI group in each direction and those in ope group were, compared pre- and postoperatively.

In all groups, MUCP is always highest in the anterior direction but FUL shows no differences in the three directions. In all directions, MUCP and FUI are higher in the normal group than in the SUI group and there is no significant change in MUCP and FUL following successful bladder neck suspension. In the normal group, PTR of anterior, lateral and posterior urethra were approximately equal, but SUI group patients demonstrated significantly decreased PTR in the lateral and posterior urethra in comparison with PTR observed in the anterior urethra. Also, PTR of the anterior urethra in the SUI group approximates that in the normal group but PTR of the lateral and posterior urethra are lower in the SUI group than in the normal group. In the ope group, in the proximal three-quarters of the FUL, PTR in the lateral and posterior urethra approximated to those in the anterior urethra postoperatively.

These findings suggest that urethral support is destructed in the SUI group as mentioned in DeLancey's hammock hypothesis and lateral and posterior weakness were corrected by bladder neck suspension. Bladder neck suspension restored the continence by constructing posterior support of urethra as the substitution for destructed urethral support.