Pressure/cross-sectional area relations in the proximal urethra of healthy males. Part 1: Elastance and estimated pressure in the uninstrumented urethra.

The pressure/cross-sectional area relation in the resting urethra during the storage phase was studied in 31 healthy male volunteers aged 23-85 years. Measurements were performed at 5-mm intervals from the bladder neck and beyond the region of high pressure, and the elastance and estimated pressure in the uninstrumented urethra (Po) were calculated at each measurement location. All subjects were further evaluated by means of symptom score, prostatic volume determined by rectal ultrasound, urethral pressure profile, cystometry, and pressure flow. The elastance and Po both varied along the urethra, with significantly higher values of both parameters in the sphincteric region as compared to the prostatic area. A significant positive correlation was found between Po and age in the prostatic parts of the urethra, whereas no correlation could be demonstrated between elastance and age in any part of the urethra. These results indicate that the prostatic parts of the urethra are readily distensible at modest intraluminal pressures as compared to the sphincteric segment, and that the intraluminal pressure required to obtain a given distension of this segment of the urethra seems to increase with age. It is suggested that the technique may prove of value in the elucidation of pathophysiological mechanisms related to benign prostatic hyperplasia, and that the technique may bring new insight into the mode of action of various treatment modalities for this disease.