Patterns of urinary flow in benign prostatic hypertrophy.

Multiple urinary flow recordings were carried out on 51 men and without bladder outlet obstruction due to benign prostatic hypertrophy. All patients were over 50 years of age. Six urinary flow patterns (types 0-5) were defined. Types 0-3 were found in patients without obstruction, while all six patients were observed in those with clinical obstruction. Following prostatic surgery, only types 1, 2 and 3 were found. Only type 5 flow pattern can be determined by flow rate alone because it is by definition on the curve obtained when peak flow rate is below 4 ml per second. In this study, no type of flow pattern was characteristic of bladder outlet obstruction due to benign prostatic hypertrophy. The supposedly characteristic type of flow pattern in this clinical condition reported by earlier workers is mainly a result of a difference in the age distribution between their control and test groups.