EP18.20: Association of chromosomal abnormalities and cardiac defects with increased nuchal translucency and/or tricuspid regurgitation in South Indian population

To evaluate the incidence of chromosomal, genetic and cardiac abnormalities in fetuses with increased Nuchal Translucency (iNT) and Tricuspid Regurgitation (TR) in singleton pregnancies undergoing ultrasound examination at 11+0 to 13+6 weeks. This is a retrospective study of prospectively collected data from tertiary fetal care centre in South India from June 2015 to December 2023. 6141 singleton pregnancies that underwent the first trimester scan as per the FMF and ISUOG guidelines and had known outcomes were assessed during this study period. The Tricuspid Valve Doppler was assessed in 5926 fetuses and these were included in the study. All scans were performed by FMF certified operators. The data was stored in Astraia software. Outcome of the pregnancies was assessed by prenatal diagnostic testing if performed, telephonic interview with parents confirming absence of any neurodevelopmental delay and examination of the hospital delivery records. The study population was divided into Group 1 with iNT and TR, group 2 had only TR and group 3 had neither iNT nor TR. 591/ 5926(9.9%) fetuses had iNT and 153(2.6%) had TR. 76 fetuses had iNT and TR. 8/ 20 (40%) had an abnormal karyotype and 39/ 68 (57.4%) had cardiac defects. 77 fetuses had isolated TR, of which 5/ 39 (12.8%) had an abnormal karyotype and 18/ 72 (25%) had cardiac defects. In the 5258 fetuses that had neither iNT nor TR, 28/ 4756(0.6%) had a chromosomal anomaly, 49/ 4756 (1.03%) had a genetic anomaly and 69/ 5230 (1.3%) had a cardiac defect. The abnormal karyotypes included 6 T21, 1 T18, 1 T13 in group 1. In group 2, there were 4 T21 and 1 CNVs. The presence of iNT along with TR increases the risk for chromosomal and cardiac anomalies significantly. It would be prudent to add meticulous assessment of tricuspid valve Doppler during the first trimester scan along with assessment of NT to improve the detection rate of chromosomal and major cardiac anomalies.