To describe the association of abnormal outcomes with fetal cystic hygroma detected when crown–rump length measures less than 45 mm, and to compare them to outcomes among fetuses with cystic hygroma detected when crown–rump length measures 45–84 mm.Methods
We performed a retrospective cohort study of fetuses with first trimester nuchal cystic hygroma from 2005 to 2015.Results
A total of 212 fetuses were included. Abnormal karyotype was found in 20 of 46 (43.4%) fetuses with cystic hygroma detected when crown–rump length measured below 45 mm, compared to 108 of 148 (73%) fetuses with cystic hygroma detected at crown–rump lengths of 45–84 mm (p = 0.001). There were no differences in rates of major structural anomaly (27% vs 36%; p = 0.53) or pregnancy loss (23% vs 7%; p = 0.22) among fetuses with normal karyotype. Those with cystic hygroma diagnosed at crown–rump lengths below 45 mm were more likely to have a normal neonatal outcome compared to cases diagnosed with crown–rump lengths of 45–84 mm (25% vs 11%; p = 0.02).Conclusion
Cystic hygroma detected when crown–rump length measures below 45 mm have lower rates of chromosomal abnormalities and a higher proportion of normal birth outcomes when compared to those detected later in the first trimester. © 2016 John Wiley & Sons, Ltd.