Sonographic assessment of fetal testicular development and descent

Objective The aim of this report is to describe techniques and to provide basic and available scientific data on the success of testicular size procedures. Methods In this prospective longitudinal study, 186 normal fetuses from 23 weeks of gestation were followed up by ultrasonography. We assessed the testis descent in the scrotum and measured the major (mm) and minor (mm) axes of the testes in the scrotum in fetuses, as well as the height in newborn infants. Testicular sizes were compared among five periods (23-26 weeks, 27-30 weeks, 31-34 weeks, ≥35weeks, and neonatal period). Results The testicular cross-sectional area increased exponentially with gestational age. The cross-sectional area of each testis in fetuses at ≥35 weeks was very similar to that in newborn infants. In both the testes, the fetal testicular cross-sectional area at ≥35 weeks was strongly correlated with the neonatal testicular volume. At 27-30 weeks, the testicular cross-sectional areas of the descended testes in fetuses with unilaterally undescended testis were significantly smaller than those in fetuses with both descended testes. Conclusion We provide basic data of fetal testis size and useful way to measure testes size available.