The importance of studying pressure-flow for predicting postoperative voiding difficulties in women with stress urinary incontinence: a preliminary study that correlates low Pdet x Qave with postoperative residual urine.

We evaluated the parameters of preoperative pressure-flow for predicting the postoperative voiding difficulties in women with stress urinary incontinence. The preoperative urodynamic study records of 14 women treated using the tension-free vaginal tape (TVT) procedure were retrospectively analyzed. Of the patients treated with the TVT procedure, urinary retention occurred in one patient, and three had a residual urine volume of more than 30 ml. All patients became completely free of stress urinary incontinence postoperatively. The lowest Pdet max (5 cmH(2)O) in the preoperative pressure-flow study was found in a patient with a remarkable postoperative residual urine volume of more than 50 ml. The second lowest Pdet max value (8 cmH(2)O) was seen in a patient with postoperative urinary retention, whose residual urine volume, however, decreased to almost zero 1 year after the operation. The preoperative Pdet max x Qave values were remarkably low for these three patients, including the one with the lowest Pdet max, with a post-void residual urine volume of more than 30 ml. The plots of Pdet max x Qave versus the age of patients show that the Pdet max x Qave values tend to decrease with aging. The preoperative Pdet max x Qave value can be an important parameter for predicting increased residual urine after TVT sling surgery.