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

Objective: To establish in-utero reference ranges for fetal transverse aortic arch diameter (TAD) and distal aortic isthmus diameter (DAID) using high-resolution ultrasound techniques. Design: A prospective, cross-sectional study was performed on 125 normal singleton pregnancies between 14 and 38 weeks' gestation. Transverse and diameter 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 was expressed by the regression equation TAD = - 1.17 + 0.169 X GA, and DAID = - 1.39 + 0.189 X GA; TAD and DAID are transverse aortic and distal aortic isthmus diameters expressed in millimeters and GA is gestational age in weeks. The correlation r = 0.924 and 0.938 was found to be highly statistically significant (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 prenatal diagnosis of congenital heart defects, including abnormal growth of the aortic arch.