The Effect of Oral Phenazopyridine on Perioperative Voiding After Midurethral Slings (EPIPhANy Study)

To determine the effect of preoperative oral phenazopyridine on postoperative voiding dysfunction in women undergoing a retropubic midurethral sling.

A single-institution randomized clinical trial was performed from September 2015 to March 2017, comparing 200 mg of oral phenazopyridine versus no phenazopyridine in patients undergoing a retropubic midurethral sling under general anesthesia with no concomitant procedures. A power calculation indicated that we required at least 40 subjects per arm. Preoperative demographics, intraoperative medications, blood loss, and complications were recorded. A standardized voiding trial was performed before discharge. Voiding dysfunction was determined by the proportion of subjects who failed a postoperative voiding trial. Pain scores were obtained before and 2 to 3 hours after the surgical procedure. Patient characteristics and surgical data were compared using χ, Fisher exact test, or Wilcoxon rank sum test.

Ninety-two subjects were enrolled in the study. Three patients cancelled their surgery and 1 had an intraoperative urethral injury, leaving 88 patients for the final analysis (44 per arm). Patient demographics showed no differences between groups. Phenazopyridine did not reduce the proportion of patients who failed the voiding trial (27%) compared with subjects who did not receive the medication (21%) (P = 0.453). Postoperative visual analog pain scores were higher in those not receiving phenazopyridine (1.76 vs 1.21, P = 0.046), but after adjusting for the difference in preoperative and postoperative pain scores, the groups showed no difference (P = 0.087).

Our prospective trial shows that phenazopyridine has no effect on short-term postoperative voiding dysfunction. This condition appears to be multifactorial, and further research is needed.