Objectives: To examine the predictive value of ultrasonic measurements obtained by transrectal ultrasonography for infravesical obstruction as evaluated by pressure flow studies.
Methods: 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.
Results: 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%.
Conclusions: PCAR is useful as a transrectal ultrasonic measurement in assessing the severity of infravesical obstruction in men with lower urinary tract symptoms.