Predictors of Postoperative Voiding Dysfunction following Transobsturator Sling Procedures in Patients with Stress Urinary Incontinence

Cho, Sung Tae; Song, Hyeong Cheol; Song, Ha Jong; Lee, Young Goo; Kim, Ki Kyung

Abstract

PURPOSE
We evaluated the influence of preoperative physical examination (PE) and urodynamic study (UDS) findings on objective postoperative bladder emptying, the subjective development of bladder storage symptoms, and patient-reported success of correction of stress urinary incontinence (SUI).
MATERIALS AND METHODS
From January 2007 to August 2008, a total of 159 female patients with SUI underwent transobturator midurethral sling surgery (TOT). The patients were selected for SUI, with no overactive bladder (OAB) symptoms, no detrusor overactivity (DO) on UDS, no pelvic organ prolapse, and no history of prior anti-incontinence surgery. Of these patients, 128 patients (aged 38-74 years; mean age, 51.8+/-7.1 years) with follow-up of at least 12 months were included in the analysis. All patients had PE and UDS findings, including Q-tip testing, free maximal flow rates (Qmax), filling cystometry, Valsalva leak point pressure, detrusor pressure at maximal flow, and maximal urethral closing pressure. The primary outcome was postoperative voiding dysfunction, defined as the subjective feeling of not empting one's bladder completely and a postvoid residual > or =100 ml. A secondary outcome, "cure" of SUI, was defined as "a negative result on the cough stress test and no subjective complaint of urine leakage." We analyzed the preoperative parameters by univariate and multivariate regression for voiding dysfunction, de novo OAB, cure rate, and the patients' satisfaction.
RESULTS
Patients with a preoperative Qmax < 15 ml/s (7 patients) had a tendency for postoperative voiding dysfunction compared with those with a Qmax 15 ml/s (15 patients) (35.0% vs. 13.9%, respectively; p=0.046). No other preoperative parameters had a statistically significant influence on postoperative voiding dysfunction. Receiver operating characteristic (ROC) analysis revealed that Qmax was a good predictor because the area under the ROC curve value of Qmax was 0.81 (95% CI: 0.73 to 0.89, p<0.001). The univariate and multivariate analysis of the preoperative PE and UDS parameters demonstrated that no significant differences and no independent risk factors were related to the postoperative de novo OAB, cure rate, or the patients' satisfaction.
CONCLUSIONS
These findings suggest that preoperative UDS results, especially Qmax, could be used to predict postoperative voiding dysfunction after the TOT procedure.