Intravesical pressure in benign prostatic hypertrophy.

Synchronous pressure and flow studies were carried out on 51 men over 50 years of age. The subjects were divided into groups based on degree of bladder outlet obstruction. Eight patients were also examined six to ten weeks after prostatectomy. Following multiple pressure and flow recordings, the mean premicturition resting intravesical pressure, the mean intravesical pressure at the commencement of voiding (the commencing intravesical pressure), the mean maximum intravesical pressure and the mean intravesical pressure at the end of voiding (mean cessation intravesical pressure) were determined for each subject. The maximum intravesical pressure varies in the same individual. A mean maximum intravesical pressure of 75 mm Hg and above indicates moderate or severe bladder outlet obstruction. However, this pressure is not of value in the determination of clinically doubtful or mild obstruction. None of the other intra-vesical pressures is of value in the diagnosis of bladder outlet obstruction. Six to ten weeks following successful prostatectomy the mean maximum intravesical pressure fell to normal limits.