Magnetic resonance imaging for locating nonpalpable undescended testicles: a meta-analysis.

BACKGROUND AND OBJECTIVE Preoperative imaging techniques may guide management of nonpalpable, cryptorchid testicles. We evaluated conventional MRI for identifying and locating nonpalpable testicles in prepubescent boys via meta-analysis. METHODS Databases including Medline were searched from 1980 to February 2012. Eligible studies included ≥10 boys with cryptorchidism/suspected cryptorchidism and reported data on testicular presence/absence and position (abdominal, inguinal, or scrotal) as determined by imaging and surgery. Two investigators independently reviewed studies against inclusion criteria. We captured the number of testicles that were correctly and incorrectly identified and located, relative to surgically verified status, and estimated sensitivity and specificity by using a random-effects model. RESULTS Eight unique prospective case series included 171 boys with 193 nonpalpable testicles (22 with bilateral testicles). Surgery identified 158 testicles (81.9%) present and 35 absent. MRI correctly identified testicles with an estimated median sensitivity of 0.62 (95% Bayesian credible interval [BCI]: 0.47-0.77) and a specificity of 1.0 (95% BCI: 0.99-1.0). MRI located intraabdominal testicles with a sensitivity of 0.55 (95% BCI: 0.09-1.0) and inguino-scrotal testicles with a sensitivity of 0.86 (95% BCI: 0.67-1.0). We were not able to obtain estimates for MRI sensitivity or specificity for locating atrophied testicles. The estimated specificity for location-specific testicles reached almost 100%. CONCLUSIONS Conventional MRI has low sensitivity for estimating the population sensitivity for identifying the presence of nonpalpable cryptorchid testicles. When testicles are identified, MRI is poor at locating both atrophied and intraabdominal testicles but performs modestly well in locating those in the inguino-scrotal regions.