Measurement of the Fetal Umbilical Cord Insertion-to-Genital Tubercle Length in Early Gestation In Utero Sonographic Study

Objectives The purpose of this study was to establish in utero reference ranges for the fetal umbilical cord insertion to genital tubercle length in early gestation. Methods A prospective cross-sectional study was performed on 140 normal low-risk singleton pregnancies between 12 and 18 weeks' gestation. The umbilical cord insertion to genital tubercle length was measured in a midsagittal section with high-resolution transvaginal or transabdominal sonography. The mean and 95% prediction limits were defined for each gestational week and analyzed by regression equations and correlation coefficients. Results Adequate measurements were obtained in 134 patients. The umbilical cord insertion to genital tubercle length as a function of gestational age was expressed by the following regression equation: umbilical cord insertion to genital tubercle length = -3.079452 + 1.09 x week (R-2 = 0.7117). The correlation R-2 = 0.7117 was found to be highly statistically significant (P < .001). The normal mean and 95% prediction limits were defined for each gestational week. During the study period, 2 cases were referred to our unit because of nonvisualization of the urinary bladder. The umbilical cord insertion to genital tubercle lengths in these cases were below the 95th percentile, confirming the diagnosis of bladder exstrophy. Conclusions The normative data established in this study maybe helpful for early prenatal diagnosis congenital bladder exstrophy.