Correlation of presumed circle area ratio with infravesical obstruction in men with lower urinary tract symptoms

To examine the predictive value of ultrasonic measurements obtained by transrectal ultrasonography for infravesical obstruction as evaluated by pressure flow studies.

In 85 men with moderate to severe lower urinary tract symptoms, ultrasonic measurements including prostatic volume, transition zone volume, transition zone index (transition zone volume/prostatic volume), and presumed circle area ratio (PCAR) were compared with urodynamic parameters obtained by pressure flow studies.

There were significant interrelationships between these ultrasonic measurements, which were all significantly greater in the obstructed patients than in the unobstructed patients. A simple regression analysis demonstrated that prostatic volume (r = 0.362, P < 0.001), transition zone volume (r = 0.373, P < 0.0005), transition zone index (r = 0.331, P < 0.005), and PCAR (r = 0.487, P < 0.0001) correlated significantly with the Abrams-Griffiths number. More importantly, a multiple regression analysis demonstrated PCAR to be the only independent determinant of the Abrams-Griffiths number. A receiver operator characteristics curve analysis showed that 0.8 was the most suitable cutoff value of PCAR for the prediction of infravesical obstruction with a diagnostic accuracy of 76.5%.

PCAR is useful as a transrectal ultrasonic measurement in assessing the severity of infravesical obstruction in men with lower urinary tract symptoms.