19: Predictors of early postoperative voiding dysfunction and other complications following a midurethral sling

Abstract

Identify preoperative predictors for failed voiding trial (VT) following isolated midurethral sling (MUS). Following IRB approval, we performed a comparative study on a retrospective cohort including all isolated MUS procedures performed between 1/1/10 to 6/30/15 at 5 academic centers. We collected demographics, medical and surgical histories, voiding symptoms, urodynamic evaluation (UDE), type of MUS and surgical time from the medical record. We excluded intraoperative complications requiring prolonged catheterization. Cases failed a postoperative VT and were discharged with an indwelling catheter or taught intermittent self-catheterization (ISC); controls passed a VT. We also recorded any adverse events such as UTI or voiding dysfunction up to 6 weeks after surgery. Bivariate analyses were completed using Student’s t-test or Mann-Whitney and Pearson chi-square as appropriate. Multivariate stepwise logistic regression was used to determine predictors of failing a VT. Four hundred two patients had an isolated MUS (317 retropubic, 82 transobturator, 3 single-incision); 22.4% failed the initial VT. At follow-up visits, 90.5% passed a second VT, and 41.7% of the remainder passed on third attempt. Bivariate analyses: Prior prolapse or incontinence surgery was similar between cases and controls (24% vs 20%, p=0.347) as were age, race, BMI, and operative time. Sense of incomplete emptying prior to surgery was noted in 33% vs 26%, p= 0.204, and recurrent UTIs were reported by 14% vs 10%, p=0.297. Overactive bladder symptoms and urge incontinence were similar in both groups, but detrusor overactivity (DO) was more common in cases (32% vs 23%, p=0.088). Mean(SD) bladder capacity was similar in both groups [406(148)mL vs 385(121)mL, p=0.203] as was max flow with uroflowmetry (UF) and pressure flow studies (PFS). Postvoid residual (PVR) with UF was 28.5(49.3)mL vs 19.2(29.1)mL, p=0.126; and on PFS was 61.6(133.8)mL vs 35.8(68.8)mL, p=0.112. Cases were significantly more likely to have a voiding type other than detrusor contraction: 41% vs 29%, p=0.044, OR 1.72 (95% CI: 1.01-2.93). There was no difference in VT failures between retropubic and transobturator routes (22% vs 24%, p=0.656). Within 6 weeks of surgery, the frequency of UTI in cases was greater than controls [22.1% vs 7.6%, p<0.001; OR 3.45 (1.78 to 6.70)]. After passing a repeat VT, cases were more likely to present with acute urinary retention [11.8% vs 3.3%, p=0.004; OR 3.91 (1.57-9.73)]. Multivariate analyses: In women with complex UDE (84% of patients), presence of DO (p=0.037, OR 1.85, 1.04-3.28) and increased PVR on PFS (per 10mL increase, OR 1.03, 1.003-1.058) predicted increased likelihood of VT failure. We did not identify any demographic or historical information among patients who did not undergo UDE that reliably forecasted VT failure. The majority of women will pass a VT on first attempt after isolated MUS. Presence of DO or increasing PVR on PFS predicted increased probability of failing initial VT while demographic and other findings were not predictive. Patients failing the initial VT are at increased risk of postoperative UTI or developing acute retention after passing a subsequent VT.