Transobturator mid-urethral sling in females with stress urinary incontinence and detrusor underactivity: effect on voiding phase

Introduction and hypothesis: To assess whether detrusor underactivity (DU) is a risk factor for voiding dysfunction (VD) after transobturator tape (TOT) and if a detrusor pressure at maximum flow (PdetQmax) value predicts postoperative VD in DU patients. Also, we examined uncomplicated patients for postoperative VD. Methods: This is a prospective long-term study on SUI patients who underwent TOT. Exclusion criteria were preoperative POP stage ≥ 2, previous anti-incontinence surgery and comorbidities. Patients were grouped by detrusor contractility using the projected isovolumetric pressure (PIP) index (PdetQmax + maximum flow rate) with values of 30–75 cmH2O indicating normal contractility. Follow-up was at 1, 3, 6 and 12 months, and then annually. All patients underwent a stress test and responded to the Urogenital Distress Inventory questionnaire and to the King’s Health Questionnaire. The subjective cure was evaluated using the Patient Global Impression of Improvement. We determined the diagnostic accuracy of PdetQmax levels using ROC curve analysis, with a cut-off point calculated for optimal sensitivity and specificity. Results: In 2007–2013, 118 patients underwent TOT. We included 50 in the undercontractility group (G1) and 50 in the normocontractility group (G2). Continence rates were 82% in G1 and 84% in G2 (mean follow-up 76 months). VD increased from 18 to 36% (p < 0.05) in G1 and from 14 to 16% (p = 0.198) in G2. De novo VD was 28% in G1 and 2% in G2. In the G1 group PdetQmax ≤ 12 cmH2O predicted postoperative VD with 71.4% specificity and 80.0% sensitivity. Conclusions: DU adversely affects the voiding phase of micturition after TOT. In DU patients, PdetQmax ≤ 12 cmH2O predicts postoperative VD.