Standardization for reliable uroflowmetry testing in adults.

Objectives: To assess if a standard hydration protocol will achieve voided volumes over 150 mL and more reliable uroflowmetry results.
Methods: This is a single-blinded crossover study of 40 patients with benign prostatic obstruction and 34 healthy volunteers. Subjects were enrolled prospectively between January and March 2019. All subjects performed two randomly ordered uroflowmetry tests. One test was performed when subjects sensed their bladder was full and had the urge to void and another one after emptying the bladder and ingesting 1.5 L of water within 1 hour (prehydration). Uroflowmetry parameters were compared between the benign prostatic obstruction group and the healthy volunteers. Uroflowmetry results were categorized as reliable, residual, and suboptimal with respect to voided volumes. This study has been registered in the UMIN Clinical Trials Registry (UMIN000035446).
Results: The benign prostatic obstruction group and the healthy volunteer group presented no difference in respect of uroflowmetry test reliability (P = .459). Uroflowmetry results were reliable in 58 (78.4%) subjects in the prehydrated group and was reliable in 30 (40.5%) subjects in the non-prehydrated group. The difference was statistically significant (P < .05). In the benign prostatic obstruction group and healthy volunteer group, the rate of reliable uroflowmetry tests was significantly higher with prehydration (P < .05). The comparative analysis of uroflowmetry parameters between tests performed with and without prehydration revealed higher values in the prehydrated group (voided volume, maximum flow rate, average flow rate, and postvoiding residual volume; P < .05).
Conclusion: Prehydration of patients with 1.5 L of water within 1 hour before uroflowmetry improves uroflowmetry outcomes. By this hydration protocol, the chance to obtain a voided volume over 150 mL is increased significantly.
(© 2020 John Wiley & Sons Australia, Ltd.)