Non‐Invasive Prenatal Testing Results, Nuchal Translucency Size, and Second Trimester Resolution Modify First Trimester Cystic Hygroma Outcomes

ABSTRACT Objectives The aim of our study was to describe outcomes of fetuses with cystic hygromas (CH) based on results of non‐invasive prenatal testing (NIPT), nuchal translucency (NT) size, and spontaneous hygroma regression. Methods This was a retrospective cohort study of all patients with a CH diagnosed on first trimester ultrasound at our institution over a 9‐year period. The primary outcomes were pathogenic genetic abnormalities, structural malformations and perinatal loss. Secondary outcomes included pregnancy termination, live birth, and a composite of primary outcomes. Results Of 294 fetuses with CH, 184 (64%) had a genetic abnormality, and among the fetuses with no known genetic diagnosis, 26 (25%) had at least one structural anomaly. Low risk NIPT result was associated with a 19% (13/71) residual risk of aneuploidy, copy number variant, or other pathogenic genetic finding and the frequency of all adverse outcomes rose with increasing NT size. Finally, of 31 cases of expectantly managed CH cases that resolved in the second trimester, only 4 (13%) had a genetic abnormality. Conclusion NIPT results, nuchal translucency size, and early resolution are modifiers in the outcomes associated with CH in the first trimester.