Urinary flow rate in benign prostatic hypertrophy.

Multiple urinary flow measurements were recorded on 12 men without bladder outlet obstruction, ten men with a clinically doubtful diagnosis of bladder outlet obstruction due to benign prostatic hypertrophy, 29 men with a proven clinical diagnosis of bladder outlet obstruction due to benign prostatic hypertrophy and eight men before and after prostatic surgery. All were over 50 years of age. Mean peak flow rates for non-obstructed men varied from 11.8 to 35.0 ml per second and the minimum threshold for mean peak flow rate in these subjects was 15.0 ml per second for voided volumes of 200 ml and above. The vast majority of subjects with obstruction had mean peak flow rates below 15 ml per second. Mean peak flow rates reverted to normal after prostatic surgery. Our findings justify the use of multiple determinations of peak flow rate as a routine screening examination in subjects who may have bladder outlet obstruction due to benign prostatic hypertrophy.