Use of ultrasound for the palpable undescended testis: a wasteful practice.

Abstract

Many primary care physicians order an ultrasound (US) before referral to specialist care for suspected undescended testis; however, the value of this practice is questionable. To determine the proportion of boys referred for suspected undescended testis who had accompanying US, the cost of this practice and the accuracy of US for testis localization when compared with physical examination by a pediatric urologist. This was a retrospective chart review at a pediatric urology service, including all patients referred for suspected undescended testis from 2008 to 2012. We determined the cost of US ordered, and calculated Cohen's kappa, sensitivity and specificity, and positive and negative predictive value. We identified 894 eligible patients; 32% (289/894) were accompanied by US. In 77% (223/289), the urologist was able to palpate the testis: 51% (147/289) had a normal/retractile testis and 26% (76/289) had a palpable undescended testis. At a cost of 71.10 CAD per US, 20 547.90 CAD was expended on this practice. Of the 223 patients with palpable testes, we were able to gather detailed US and physical examination results for 214 patients. Cohen's kappa was 0.06 (95% CI -0.005, 0.11; P = 0.10). US had 92.8% sensitivity (95% CI 84.1, 96.9%) and 15.2% specificity (95% CI 10.2, 21.9%) to detect an undescended testis. The positive predictive value was 34.2% (95% CI 27.8, 41.3%), while the negative predictive value was 81.5% (95% CI 63.3, 91.8%). Referral of patients for suspected undescended testis should not be accompanied by an US study as US is not useful in these cases.