Introduction and hypothesis: To determine if administration of a standard 400 mg oral dose of riboflavin (vitamin B2) was comparable to phenazopyridine (pyridium) for evaluating ease of visualization of ureteral jets at the time of cystoscopy.
Methods: A three-arm double-blinded, randomized controlled study was performed consisting of thiamine as placebo, phenazopyridine, and riboflavin. Agents were administered the morning of surgery prior to surgical procedure. The primary outcome was the ease of visualization of the ureteral jets based on a grading of urine stain intensity on a 7-point color scale, where 1-2 were minimal yellow staining, 3-4 were moderate yellow staining, and 5-7 defined as intense yellow staining. Analysis of covariance (ANCOVA) was used with pairwise comparison to characterize urine stain intensity as a continuous variable among the three groups controlling for age, BMI, creatinine, and time from ingestion of medication to first cystoscopy.
Results: Eighty-four subjects were randomized with a mean ± SD age of 46.25 + 11.36 and BMI of 32.46 + 6.59. Riboflavin did have moderate or intense staining in 57% of cases; however, there was no significant difference between urine staining intensity compared to placebo (p = 0.21). There was a statistically significant increased urine staining intensity for phenazopyridine compared to placebo (p = 0.001) and for phenazopyridine compared to riboflavin (p = 0.001).
Conclusions: Phenazopyridine provided statistically significantly greater urine staining compared to both riboflavin and placebo and should be considered primarily for ease of ureteral jet visualization.
Keywords: Cystoscopy; Phenazopyridine; Pyridium; Riboflavin; Ureteral jets.
© 2021. The International Urogynecological Association.