Effectiveness of Assessing Ureteral Patency Using Preoperative Phenazopyridine.

Objectives: The aims of this study were to determine the efficacy of phenazopyridine when used intraoperatively to assess ureteral patency and to investigate factors that may influence its efficacy.
Methods: This is a retrospective chart review performed at the Olive View-UCLA Medical Center, a Los Angeles County teaching hospital, from January 2014 through July 2016. Patients undergoing cystoscopy at the time of gynecologic surgery were identified via department case logs. All women receiving preoperative oral phenazopyridine were included. If ureteral flow was unable to be visualized with phenazopyridine alone, the medication was deemed ineffective, and sodium fluorescein was given intraoperatively. Patients were divided into a phenazopyridine effective or phenazopyridine ineffective group. Patient demographics, renal function, intraoperative fluids and urine output, estimated blood loss, timing and dose of medication administration, and complications were gathered from the chart and compared between groups using Fisher exact test, 2-sample t test, Wilcoxon test, and logistic regression for multivariable analysis. P < 0.05 was determined to be significant.
Results: Preoperative phenazopyridine was effective in 190 (91.8%) of 207 patients. It was ineffective in 17 patients who then required intraoperative sodium fluorescein. The group in which phenazopyridine was effective was more likely to have been given a 200-mg (vs 100-mg) dose (P = 0.02) and had lower intraoperative urine output (median, 450 vs 800 mL; P = 0.002).
Conclusions: Preoperative oral phenazopyridine is effective in more than 90% of cases to detect during gynecologic surgery. A higher phenazopyridine dose and lower intraoperative urine output were associated with increased efficacy.