Scrotal testis size in unilateral non-palpable cryptorchidism, what it can and cannot tell: Study of a Middle Eastern population.

BACKGROUND: Predicting the fate of a unilateral non-palpable testis based on its scrotal counterpart has been recommended by some, yet disputed by others, and the question remains open.

OBJECTIVE: To investigate the accuracy of contralateral testis hypertrophy in predicting the absence of a unilateral non-palpable testis in a Middle Eastern population.

STUDY DESIGN: This retrospective study included all patients referred to the present institution with unilateral non-palpable testis between June 2010 and August 2014, who had undergone laparoscopy. The scrotal testis was examined by sonography for size and volume, and diagnostic laparoscopy was utilized to determine the state of the cryptorchid testis.

RESULTS: Of the 135 referred patients, 64 were aged ≤8 years, 29 were 9-18 years, and 42 were >18 years old. Diagnostic laparoscopy revealed 63 intra-abdominal testes, 20 small intra-inguinal testes, 32 vanished testes, and 20 nubbins or aplasia (Summary fig.). Scrotal testis volume was only a modest predictor for absence of the contralateral gonad in adult patients in whom a 22 ml cut-off yielded 64.3% sensitivity and 92.9% specificity. For those aged <18 years, overall accuracy was poor and dropped below 60%. Relative enlargement of contralateral testis in decreasing order of size was observed in patients with primary monorchism, followed by those with secondarily atrophic or nubbin testis, and then those with normal sized inguinal or abdominal testis.

DISCUSSION: Unlike some previous series, which based their conclusions upon open exploration and mostly studied pre-pubertal subjects, the present results exclusively from laparoscopic exploration suggested that contralateral testis volume is a poor and inconsistent predictor of monorchism in children, and marginally predictive for young adults with unilateral non-palpable testis. This study comprised a reasonably large overall sample size compared with preceding reports; however, the number of patients within in each age group was limited. Greater numbers could allow for statistical comparison stratified by age group, for which this study was not powered.

CONCLUSION: Contralateral testis volume predicts, with modest accuracy, monorchism in adults with unilateral non-palpable testis. In younger patients, the overall predictive accuracy of scrotal testis size is poor and not consistently dependable.