Nonpalpable testes: Ultrasound and contralateral testicular hypertrophy predict the surgical access, avoiding...

In up to 20% of patients presenting with undescended testes, one or both are non-palpable. Whereas the most reliable means to exclude an abdominal testis is laparoscopy, there has been a lot of debate about the role of inguinal ultrasound (US) in detecting non-palpable inguinal testis. While we do not aim to add another paper claiming the benefits of US, we wanted to determine the excess capability of US to determine the correct surgical approach - inguinal or laparoscopy. In the light of avoiding unnecessary diagnostic laparoscopies, even the cost-effectiveness raised in many current papers might be called into question.

Of a total of 684 boys who underwent surgery for undescended testes at our department between 2011 and 2014, in 58 (8.5%), one or both testes were neither palpable preoperatively nor under general anesthesia. These boys were examined by two experienced pediatric urologists clinically as well as by US. Besides the size of the contralateral testis, the presence of a testis in the inguinal channel was investigated. The additional impact of US over clinical exam and consideration of the size of the contralateral testis was assessed by means of intra-individual comparisons using Cochran-Q as well as McNemar tests.

Clinical exam without considering the size of the contralateral testis had a sensitivity of 9% (95% CI 2-24%) and a specificity of 100% (95% CI 86-100%) to accurately predict the surgical approach deemed appropriate postoperatively. The consideration of the size of the contralateral testis - taken as an isolated factor - accurately predicted the surgical approach with a sensitivity of 21% (95% CI 9-38%) and a specificity of 88% (95% CI 68-97%). Ultrasound accounted for a sensitivity of 53% (95% CI 35-70%) and a specificity of 100% (95% CI 86-100%). The addition of US increased the sensitivity to correctly predict an inguinal incision from 29% to 71% and specificity slightly increased from 88% to 92%. This difference is significant (p = 0.008) in the bilateral McNemar test (Figure).

Inguinal US of non-palpable testes and measurement of the contralateral testis are synergistic in predicting the surgical approach. The addition of ultrasound to a clinical exam, performed also under general anesthesia and by an experienced pediatric urologist significantly increases the prediction of the correct surgical approach. Our results translate into five boys needing an US of the NPT to prevent one laparoscopy. Whereas cost-effectiveness of US might be debatable in regard to different healthcare systems, it is proven to be an effective, non-harmful tool to avoid unnecessary diagnostic laparoscopies.