P27.07: Feasibility of basic fetal heart imaging during first trimester

Abstract

Prospective study to evaluate the feasibility of obtaining standard basic fetal heart images during routine first trimester screening. From January 2010 up to December 2016 (7 years), 4518 pregnant women were examined for the purposes of the 1st trimester analytical sonogram. Singleton pregnancies, after spontaneous conception or as a result of IVF were included. All fetuses were characterised as low risk for congenital heart defects. Mothers' average age was 32.4 years (17-43). Mothers' average BMI was 24.8 (18.1-41). The gestational age during examination was on average 12+5 weeks (11+0-13+6), the CRL 64mm (46-81). Attempts were made to image the four-chamber view, the interventricular septum, the outflow and the cross-over of the great vessels and the transverse imaging of the 3 vessels-trachea in the upper part of the thorax. B-mode and bidirectional colour Doppler flow imaging were used in all cases. All images were reviewed offline and evaluated directly after every examination. Fetuses with well-visualised but atypical images were excluded. The sonographic access was transabdominal (82%; 3705/4518), transvaginal (2%;90/4518) or both (16%;723/4518). A satisfactory imaging of a normal fetal cardiac four-chamber view was achievable in 87% (3930/4518) and of a normal transverse three vessel-trachea view in 83% (3750/4518) of the cases (in 13% / 17% technically not feasible). Overall in both, 4CV- and 3VT-view, satisfactory visualisation was obtained successfully in 79% (3570/4518) of fetuses with typical first trimester heart images. The mean additional duration of the examination was less than four minutes (1.3-8.8) if the fetus was lying in the typical for NT-measurement neutral position. The attempt of an early sonographic imaging of the fetal cardiac anatomy is very important for a timely prenatal diagnosis of major congenital heart diseases. The examination conditions are often difficult and require well-experienced examiners. It is feasible to perform basic fetal heart examination during routine first trimester screening.