Oral Riboflavin to Assess Ureteral Patency During Cystoscopy: A Randomized Clinical Trial

To evaluate whether oral riboflavin is more effective than placebo as a marker of ureteric patency at cystoscopy.

Patients scheduled for gynecologic surgery where cystoscopy was a planned component of the procedure were randomized to receive riboflavin 400 mg or placebo orally the night before surgery. During cystoscopy, the operating surgeon visualized ureteric jets and video recorded the cystoscopy portion of the procedure. The primary outcome was to determine whether orally administered riboflavin produced stronger yellow color of urine seen on cystoscopy than placebo on a 3-point scale. Secondary outcomes were to assess whether riboflavin administration improved ease of identifying ureteric jets (5-point scale) and whether a greater proportion of patients had both ureteric jets visualized with riboflavin compared with placebo. A sample size of 33 per group was planned.

From June 28, 2017, to February 19, 2018, 72 women were screened and 66 were randomized, with 33 patients in each study group. The groups were similar in age, weight, body mass index, and ethnicity. The patients in the riboflavin group had significant increase of yellow-colored urine as rated by the operating surgeon, with a median of 2 compared with 1 on a 3-point scale (P<.001). The ureteral jets were more easily visualized in the riboflavin group as rated by the operating surgeon, with a median of 5 compared with 4 on a 5-point scale (P<.013). Bilateral ureteral patency was confirmed in 30 of 33 women (91%) in the riboflavin group and in 28 of 33 women (85%) in the placebo group (P=.71).

The administration of riboflavin before gynecologic surgery improves the ease of visualizing the ureteric jets by inducing yellow coloration of the urine.

Australian New Zealand Clinical Trials Registry, 12616001367437.