Effects of menstrual cycle and urinary tract instrumentation on uroflowmetry

We sought to compare bladder emptying function in normal women during the proliferative and secretory phases of the menstrual cycle and to evaluate whether urethral catheterization affected uroflowmetry parameters. Forty-nine normal volunteers (ages 19-42 years) were recruited and underwent uroflowmetry in the proliferative and secretory phases of the menstrual cycle. A serum progesterone level of <3.0 ng/mL defined the proliferative phase. During the proliferative phase, volunteers underwent uroflowmetry analysis when a sensation of fullness was appreciated. A post-void residual volume was determined, and the bladder was filled with 400 mL of normal saline. Repeat uroflowmetry analysis was then performed. This two-step procedure was repeated at a separate visit during the secretory phase. Voided volume, residual volume, maximum and average flow rates, time-to-maximum flow, and duration of flow were recorded. Wilcoxon signed-rank tests were used for statistical analysis. A two-tailed alpha value of <0.05 defined statistical significance. Our analysis was limited to the 33 patients whose predicted menstrual dating correlated with the obtained progesterone levels. During the follicular phase, we found significantly faster maximum (P < 0.0001) and average flow rates (P = 0.01), along with a shorter time-to-maximum flow (P < 0.0001) and shorter duration of flow (P < 0.0001), during the pre-catheterized void than the post-catheterized void. Similar results were observed in the secretory phase with the exception of a slightly higher residual volume (P = 0.05). No difference was seen in any measured uroflowmetry parameter when comparing similar voids between phases of the menstrual cycle. We conclude that when evaluating pre-menopausal patients, uroflowmetry may be scheduled and performed during either phase of the menstrual cycle. Neurourol. Urodynam. 19:147-152.