Effect of Preoperative Low Maximal Flow Rate on Postoperative Voiding Trials after the Midurethral Sling Procedure in Women with Stress Urinary Incontinence

Objectives: To evaluate the effects of preoperative low maximal flow rate (Qmax) on voiding trials after the midurethral sling (MUS) procedure in women with stress urinary incontinence (SUI). Methods: One hundred and sixty-eight women who underwent MUS procedure were enrolled. Preoperative free uroflowmetry was performed and patients were divided by Qmax. Low Qmax was defined as a Qmax under 15 mL/sec with voided volume at least 150 mL. Surgical results, failure of voiding trial, and postoperative uroflowmetry parameters were compared between the groups. Failure of voiding trial was defined by a PVR more than 100 mL on postoperative uroflowmetry. Results: At the discharge day, there were 42 cases showing failure of voiding trial and 33 cases requiring CIC, but only one patient showed failure of voiding trial at 12 months postoperatively. Overall, 48 patients had preoperative low Qmax. Low Qmax group showed lower Qmax in all of postoperative uroflowmetry, but there were no significant differences in the rate of postoperative voiding trial failure or CIC. The low Qmax group was then divided into two groups according to the preoperative detrusor pressure at Qmax over and under 20 cmH₂O in pressure flow study. Comparing the two groups, no significant differences were observed in the cure rate, voiding trial failure or CIC. Conclusions: Our results suggest that women with preoperative low Qmax experienced no definite unfavorable voiding problem from the MUS procedure compared to those with normal voiding function. MUS procedure may be regarded as a safe and successful procedure in SUI women with low Qmax.