Voiding dysfunction (VD) may occur in 2-20% of patients following surgery for stress urinary incontinence (SUI). Urodynamic studies (UDS) have been proposed as a means of identifying patients at risk for VD.
Our objective was to determine if preoperative urodynamic findings predict postoperative VD after pubovaginal sling (PVS) and Burch colposuspension (BC).
Materials and Methods
Preoperative, standardized UDS were performed in all participants in the Stress Incontinence Treatment Efficacy Trial, in which patients with SUI were randomized to undergo PVS or BC. VD was defined as the need for catheterization at any time following the 6 week postoperative visit, and/or the need for PVS or BC takedown. Preoperative urodynamic parameters investigated included: PVR following noninvasive flow (NIF), maximum flow during NIF (NIF max), maximum flow during pressure flow study, change in vesical pressure at maximum flow, change in abdominal pressure at maximum flow, and change in detrusor pressure at maximum flow. Women with preoperative PVR > 150ml or NIFmax of < 12 ml/second were excluded unless advanced pelvic prolapse was also present. T tests or Wilcoxon rank sum tests were used to compare mean or median UDS values by treatment group.
Among the 655 women who were randomized and underwent surgery, 57 developed VD, including 8 in BC and 49 in PVS groups. Of these 57, 38 were defined as VD due to catheterization beyond 6 weeks, 3 underwent surgery takedown and 16 both needed catheterization beyond 6 weeks and underwent surgery takedown. All 19 women who had surgery takedown were in the PVS group. No pre-operative UDS finding was associated with an increased risk of VD in any group. Mean NIF max values were similar among women with VD in the entire group (23.4 vs. 25.7 ml/sec, p=0.16), and in the PVS group (23.1 vs. 25.7, p=0.17). Voiding pressures and degree of abdominal straining did not predict patients likely to develop VD.
In this carefully selected group of women with stress-predominant urinary incontinence, preoperative UDS did not predict postoperative VD, including risk of takedown in the PVS group. Our findings may be limited by our fairly stringent exclusion criteria, and studying a group believed to be at greater risk for VD could alter these findings. Additionally, utilizing a different definition for VD, including those with subjectively worse voiding though not meeting our objective criteria, could yield differing results. In this cohort, however, UDS was unable to predict postoperative voiding dysfunction after surgery for SUI.