The volume of retractile testes

We used ultrasound to determine the volume of retractile testes in boys and compared these volumes with normative testicular volume values.

A total of 171 boys were enrolled in the study, of whom 14 were excluded from analysis. The 157 boys included (age 0.8 to 11.5 years) were recruited from 2 different populations. The first subgroup comprised 92 boys previously excluded from a study aimed at obtaining normative values of ultrasonographically scanned testes. The second group included 65 boys who had been referred to our outpatient clinic for nonscrotal testis and who were diagnosed with retractile testis. Testicular volume was measured by ultrasound in a scrotal position or in an inguinal position. Three separate transverse and longitudinal images of each testis were recorded. Length, width and height were measured, and the volume was calculated with the formula for an ellipsoid, π/6 × length × width × height. The highest value of the 3 testicular volumes was determined and taken as the volume measurement.

The volumes measured by ultrasound for the 157 boys with 276 retractile testes ranged from 0.18 to 1.49 ml (mean 0.50). The volumes of the retractile testes were significantly smaller than normative values (p <0.001). Furthermore, the testicular volumes of retractile testes measured in an inguinal position were significantly smaller than those measured in a scrotal position (p <0.001).

The volumes of retractile testes are significantly smaller than recently determined normative values.