Objective measurement of testicular volume by ultrasonography: evaluation of the technique and comparison with orchidometer estimates.

Ultrasonography of the scrotum is a valid and safe method for differentiating testicular and extratesticular disease. In the present study the accuracy and reproducibility of ultrasonographic estimation of testicular volume was evaluated. A high correlation (r = 0.992) between actual testicular volume (measured by weighing and water displacement) and the volume determined by ultrasonography was found on examination of 14 tests from patients at autopsy without any systematic under- or over-estimation. The ultrasound method proved to be highly reproducible with a coefficient of variation of 7.0 +/- 0.7%. Using different ultrasound scanners did not significantly influence the results obtained. The comparison of Prader orchidometer measurements, performed by four different clinical investigators, and ultrasonography in 256 patients revealed a significant correlation of 0.91, but the degree of correlation was dependent on the investigator's clinical experience. Volume estimates by comparative palpation appear to be valuable in most clinical settings. Ultrasonography provides an excellent tool for determining testicular volume when objective, accurate and reproducible measurements of testicular volume are required.