Reference value of testicular temperature measured by finite element analysis after first staged inguinal orchidopexy in children with abdominal testis and short spermatic cord.

This study aims to build a 3D reconstruction computed simulation model and to establish a regression equation for detecting the testis's temperature by its location after first staged open orchidopexy in children with abdominal undescended testis (UDT) and short spermatic cords. In this cross-sectional study, we enrolled 31 children with abdominal UDT and short spermatic cords who underwent first staged orchiopexy between 2017 and 2020. Using ultrasonography to obtain the testis's location distance from the skin surface (X1), external iliac vessel (X2), and internal inguinal ring (X3), we input the data into a 3D reconstruction computed simulation along with COMSOL to calculate the testicular temperature. We also used multivariate regression to establish the testicular temperature regression equation from the gathered data. The mean age of the participants was 4.47 ± 1.21 years. The mean size of the operated testis was 0.39 ± 0.13 cc. The mean distance of the testis from X1, X2, and X3 was 3.27 ± 1.25 mm, 21.06 ± 6.42 mm, and 27.19 ± 10.09 mm, respectively. The testicular temperature regression equation derived from testis location was calculated by the formula: 34.57 + 0.0236 X12 - 0.0105 X2 - 0.0018 X3. The concordance for testis temperature calculated via the computational method and regression equation was 83%. The current study provided a reference value for the testicular temperature of children with abdominal UDT and short spermatic cords after the first stage of orchiopexy. A testicular temperature regression equation can be established based on the testis location, which will provide relevant information for the testicular development assessment, disease diagnosis, and follow-up, and possibly determination of the time of the second stage of orchiopexy.