Changes in Values of Urethral Closure Pressure and its Position after Burch Colposuspension – Predictive Value of MUCP and VLPP for Successful Rate of this Operation

Overview

Objective:
To ascertain how the Burch colposuspension affects the value and position of MUCP in women without any previous uro-gynaecological operation. If possible, also to determine how the values of these parameters differ between groups of women who are free from problems after the operation, women who suffer urgency, and women who continue to suffer from stress incontinence. Furthermore, to ascertain whether the pre-operation values of MUCP and VLPP have any predictive value in determining the success rate of the Burch colposuspension. In addition, to ascertain whether in ultrasound examination we can observe any differences in urethra mobility between subgroups of women with various operation results.

Design:
Cross-sectional clinical study.

Settings:
Gynecological and Obstetric Clinic, First School of Medicine of Charles University and General Faculty Hospital, Prague.

Materials and Methods:
69 women after Burch colposuspension were included in the study. The average age was 51.9 (SD=7.8), BMI 26.9 (SD=3.9) and parity 2.1 (SD=0.6). A urodynamic examination was performed on the patient in the supine position, the urinary bladder was filled with 300 and 500 ml of normal saline solution. The pressure profile was examined at rest, at maximal Valsalva manoeuvre and while coughing. During examination of the urethral pressure profile we ascertained MUCP, the functional length of the urethra (FUL) and the relative distance of the MUCP point from the inner urethral orifice, which was calculated as the ratio of the MUCP position with respect to FUL. To determine position and mobility of urethra, perineal ultrasound examination was performed on patients in supine position, using Acuson 128 XP 10 equipment, 5 MHz convex abdominal probe. The bladder was filled with 300 ml of saline. Polar coordinates (distance p, angle gamma) were employed when determining the position of UVJ and of the centre of urethra, defined at 17 mm distance from inner urethral orifice. Of the 69 patients who underwent the operation 62 were examined after the operation, 48 subsequently had no problems (A), 5 suffered with de novo urgency or the urgency symptoms were worse (B), and in 9 (C) mild stress incontinence still persisted. The data were summarised as means with SD and as medians. Measurements before and after the operation were compared using the paired t-test and paired Wilcoxon test where appropriate. Subgroups A, B, C were compared using Kruskal-Wallis test or Pearson χ²-test where appropriate. The level of significance was set to 0.05. Statistical software R version 2.1.1 was used throughout the analysis.

Results:
No statistically significant changes were observed in values of MUCP before and after surgery, at rest, at Valsalva or while coughing, or with varying volumes of the urinary bladder of 300 and 500 ml before operation. Nor did we observe any difference in values of MUCP between the individual subgroups (A, B, C) of patients after surgery. We noted statistically significant differences in values of MUCP with varying volumes of the bladder of 300 and 500 ml after operation, the value of MUCP being higher with larger volume of the bladder at rest and while coughing. We observed statistically significant shortening of FUL after operation for bladder volume of 500 ml at rest only. The distance of the point of MUCP from the inner urethral orifice was significantly shorter only for bladder volume of 300 ml during Valsalva. No statistically significant differences in these parameters were observed between subgroups A, B, C.

In the group of patients with MUCP before surgery ≤ 30 cm H₂O (10 out of 61 bladder volume 500 ml), 70% women were without problems after the operation. Among women with MUCP >30 cm H₂O, 80% were without problems. This difference, however, was not statistically significant. The same is valid for women with VLPP ≤ 60 cm H₂O, 71% women were without problems after the operation and women with VLPP > 60 cm H₂O where 91% were without problems; there was no statistically significant difference in success rate of this operation between these groups. The results of ultrasound examination imply that the operation change the position of UVJ or the middle of urethra at rest and during Valsalva manoeuvre. From the ultrasound parameters we can conclude that the operation changed the position of UVJ and the middle of the urethra forward at rest and restricted the mobility of the urethra during Valsalva manoeuvre.

Conclusions:
The results of our study imply that Burch colposuspension, if properly placed and not tight, does not change MUCP either at rest or at Valsalva. The distance of the point of MUCP from the inner urethral orifice was significantly shorter only for bladder volume of 300 ml during Valsalva. No statistically significant differences in these parameters were observed between subgroups A, B, C. From the ultrasound parameters we can conclude that the operation changed the position of UVJ and the middle of the urethra forward at rest and restricted the mobility of the urethra during Valsalva maneuver. There is a slight paradoxical diminishing of the gamma angle during the Valsalva maneuver in the subgroups of patients with de novo urgency or where the urgency symptoms were worse (B), implying different movement of the urethra.

Pre-operation values of MUCP and VLPP cannot be used to predict the effect of the operation, though we are aware of the fact that our results were ascertained on a rather small number of patients in the groups of patients with complications.

Key words:
female urinary incontinence, urethral hypermobility, maximum urethral closure pressure, Valsalva leak-point pressure