Unfavorable postnatal outcome with significant dilation of the fetal main pulmonary artery near term.

Introduction: Fetal echocardiography in third trimester is relatively rare reported and there is no data, what is the clinical meaning of the main pulmonary artery (MPA) dilatation in third trimester or before the delivery in fetuses with congenital heart defect. We analyzed the neonatal follow‐up in cases of significantly dilated MPA diameter to better understand its clinical significance. Material and Methods: Retrospectively 238 healthy singleton fetuses were selected as a reference group. Consecutive percentiles for MPA diameter according to the gestational age were calculated. In second step, we selected cases whose MPA diameter measured at the level of three vessel trachea view (3VT view) was pointedly above 95th centile in third trimester of pregnancy, according to the obtained data of our healthy population. Results: There were 11 fetuses, with dilated MPA diameter (range 12–13.5 mm), who had last echocardiography performed at 37.6 weeks of gestation. There were 11 isolated heart defects: 7 cases with HLHS, 2 with d‐TGA, and 2 cases with CoA. Mean neonatal weight was 3,345 g, with Apgar score 8–10. About 10 newborns out of 11 had cardiac surgery at the mean 12th day of the postnatal life and 8 of them died on the mean 23rd day. Autopsy was performed in 5 cases. In all of them histopathology reports described pulmonary hypertension in addition to cardiac structural abnormalities. Conclusion: Severe dilation of the fetal MPA before the delivery suggested prenatal abnormal lung development and was a poor prognostic factor. In these cases postnatal pulmonary hypertension should be suspected. [ABSTRACT FROM AUTHOR]