Fetal aortic arch measurements between 14 and 38 weeks' gestation: in-utero ultrasonographic study

Objective To establish in-utero reference ranges for fetal transverse aorti c arch diameter (TAD) and distal aortic isthmus diameter (DAID) using high- resolution ultrasound techniques. Design A prospective, cross-sectional study runs performed on 125 normal si ngleton pregnancies between 14 and 38 weeks' gestation. Transverse and diam eter and DAID were measured by transvaginal ultrasonography until 17 weeks' gestation, and by abdominal ultrasound between 18 and 38 weeks' gestation. Results Transverse arch diameter as a function of gestational age runs expr essed by the regression equation TAD = - 1.17 + 0.169 x GA, and DAID = - 1. 39 + 0.289 x GA; TAD and DAID are transverse aortic and distal aortic isthm us diameters expressed in millimeters and GA is gestational age in weeks. T he correlation r = 0.924 and 0.938 was found to be highly statistically sig nificant (P < 0.001) for TAD and DAID. The normal mean of TAD and DAID per week and the 95% prediction limits were also defined. Conclusions The normative data established by us may be helpful in the pren atal diagnosis of congenital heart defects, including abnormal growth of th e aortic arch.