Evaluation of Three-Vessel View Intervessel Distance Measurements in Fetuses Without Congenital Cardiac Defects

We aimed to compare the intervessel distances on standard 3-vessel views during fetal echocardiography across nonanomalous fetuses between 18 and 23 weeks' gestation. The intervessel measurements included the distances between the main pulmonary artery (PA) and ascending aorta (Ao) (PA-Ao), between Ao and superior vena cava (SVC) (Ao-SVC), and between PA and SVC (PA-SVC).

Throughout a 2-year period, 95 low-risk pregnancies as controls were included. Two evaluators measured intervessel distances from archived images. Scatter plots that included gestational age, femur length (FL), biparietal diameter (BPD), and intervessel distance measurements for nonanomalous fetuses were formed. Inter- and intraobserver reliabilities were assessed by intraclass correlations (ICC).

In normal fetuses, PA-Ao and Ao-SVC distance values did not significantly change (p = 0.62 and p = 0.09, respectively), although PA-SVC distance measurements increased (p = 0.0001) with increasing gestational weeks. Interobserver and intraobserver agreement for PA-Ao distance were moderate (ICC, 0.63) and high positive (ICC, 0.79); for Ao-SVC distance, it was low positive (ICC, 0.47) and moderate (ICC, 0.59); for PA-SVC distance, it was high positive (ICC, 0.76) and high positive (ICC, 0.89), respectively.

Reference intervals for intervessel distances PA-Ao, Ao-SVC, and PA-SVC in the three-vessel view at 18-23 weeks of gestation were established.