Usefulness of a prevoiding transabdominal sonographic bladder scan for uroflowmetry in patients involved in clinical studies of benign prostatic hyperplasia.

Objective: Flow rate measurements in clinical studies require an amount of voided urine greater than 125 to 150 mL. Often patients do not void sufficient amounts of urine, and having them produce repeated flows is often difficult. Transabdominal sonographic scanning of the bladder is a simple method for estimating bladder volume.