Optimal Cutoff Value of Contralateral Testicular Size for Prediction of Absent Testis in Japanese Boys With Nonpalpable Testis

ObjectivesTo investigate the accuracy of contralateral testicular hypertrophy in Japanese boys with a nonpalpable testis and to determine the optimal cutoff value of the contralateral testicular size to predict the absence of the testis.MethodsFrom December 2003 to November 2009, we evaluated 55 boys <60 months old (mean age 19.4) with a unilateral nonpalpable testis and compared their findings with those of a control group. The control group included 20 age-matched boys with 40 testes. The nonpalpable status of the testes was diagnosed by physical examination, and the contralateral testis was measured with calipers before surgery. A sensitivity and specificity analysis were performed using computer software.ResultsAt surgery, the testis was found in 22 of the 55 boys and was absent in 33. Of the 33 boys with an absent testis, 4 had a blind-ending vessel and 29 had an atrophic cord and testicular nubbin in the canal or scrotum. The mean contralateral testicular length and volume in the boys with an absent testis was 22.4 mm and 2.20 cm3 compared with 16.6 mm and 1.10 cm3 in the boys with the testis present and 16.6 mm and 1.18 cm3 in the controls, respectively (P < .01). The predictive accuracy, sensitivity, and specificity for an absent testis was 87.3%, 81.8%, and 95.5% for the length and 85.5%, 84.8%, and 86.4% for the volume, respectively, at the optimal cutoff value of 21 mm in length and 1.6 cm3 in volume.ConclusionsOur data have shown that contralateral testicular hypertrophy strongly indicates an absent testis in Japanese boys. The optimal cutoff for contralateral testicular hypertrophy with calipers was 21 mm and 1.6 cm3. This result has provided valuable information for preoperative counseling and treatment planning.