Diagnosis of major heart defects by routine first-trimester ultrasound examination: association with high nuchal translucency, tricuspid regurgitation and abnormal flow in the ductus venosus

Objective: To examine the association between fetal major heart defects and high nuchal translucency thickness (NT), tricuspid regurgitation and abnormal flow in the ductus venosus in a large population of singleton pregnancies undergoing a routine ultrasound examination at 11-13
weeks’ gestation.

Methods: This was a retrospective study of prospectively collected data from singleton pregnancies attending for a routine ultrasound scan at 11-13 weeks’ gestation which included examination of fetal anatomy, measurement of NT, and assessment of blood flow across the tricuspid valve and in the ductus venosus according to a standardized protocol. The incidence of fetal NT ≥95th and NT ≥99th percentile, tricuspid regurgitation and reversed a-wave in the ductus
venosus in fetuses with and without major heart defects was determined and the performance of each marker and their combination in the detection of major heart defects was calculated.

Results: The study population of 93,209 pregnancies with no apparent chromosomal abnormality included 211 (0.23%) with major heart defects and 92,998 morphologically normal neonates. In 113 (53.6%) of the major heart defects the diagnosis was made at the 11-13 weeks scan, in 82 (38.9%) at the 18-24 weeks scan, in 10 (4.7%) at the third-trimester scan and in 6 (2.8%) postnatally. At the 11-13 weeks scan we diagnosed all cases of tricuspid or pulmonary atresia and polyvalvular dysplasia, >90% of cases of hypoplastic left heart syndrome or atrioventricular septal defect, about 60% of complex heart defects and left atrial isomerism (interrupted inferior vena cava with normal intracardiac anatomy), 30-40% of tetralogy of Fallot and arch abnormalities, 25% of tricuspid valve abnormalities, about 15% of transposition of great arteries, but none of aortic or pulmonary stenosis and common arterial trunk. Fetal NT ≥95th percentile, NT ≥99th percentile, tricuspid regurgitation, or abnormal ductus venosus flow was observed in 77 (36.5%), 45 (21.3%), 61 (28.9%), and 58 (27.5%) of the fetuses with major heart defects, respectively, and in 5,678 (6.1%), 857 (0.9%), 1,136 (1.2%), and 1,644 (1.8%) of those without heart defects. Any one of NT ≥95th, tricuspid regurgitation or abnormal flow in the ductus venosus was found in 117 (55.5%, 95% CI 48.5–62.3%) of the fetuses with heart defects and in 8,166 (8.8%, 95% CI 8.6-9.0%) of those without heart defects. Any one of NT ≥99th percentile and the other two markers was found in 99 of the fetuses with heart defects (46.9%, 95% CI 40.0-53.9%) and in 3,517 of those without heart defects (3.8%, 95% CI 3.7-3.9%).

Conclusion: At 11-13 weeks’ gestation measurement of fetal NT and assessment of flow across the tricuspid valve and in the ductus venosus can lead to the early diagnosis of major heart
defects.

Fetal Medicine Foundation. Grant Number: Charity No: 1037116