EP18.22: First trimester cystic hygromas: what factors modify prognosis?

To describe outcomes of fetuses with first trimester cystic hygromas (CH) based on nuchal translucency (NT) size, cell-free DNA (cfDNA) aneuploidy screening results and resolution of the CH. We performed a retrospective cohort study of all patients diagnosed with a septated CH on first trimester ultrasound at our institution over a 9-year period. The primary outcomes were pathogenic genetic abnormalities (aneuploidy, copy number variant, single gene variant), structural anomalies, and perinatal loss (miscarriage or fetal demise). Secondary outcomes included live birth and a composite of the primary outcomes. Of 294 fetuses with cystic hygroma, 184 (63%) had a genetic abnormality, 63 (21%) a structural anomaly, and 26 (9%) were lost to follow-up. Of 268 cases with outcomes data, 44 (17%) had a perinatal loss, 222 (76%) had the composite abnormal outcome and 68 (25%) had a live birth, of which only 38 had no genetic or structural abnormalities. We stratified outcomes based on NT size; the frequency of all primary outcomes rose with an increasing NT (see figure 1). For fetuses with a low risk cfDNA result (n = 71), 13 (19%) had a genetic abnormality, 18 (27%) a structural anomaly, and 33 (47%) the composite outcome. Finally, of continuing pregnancies followed with expectant management who had a resolved CH in the second trimester (n = 31), 4(13%) had a genetic abnormality, 3 (10%) had a structural anomaly, 6 (20%) had the composite outcome; all 26 cases with available birth data had a live birth, of which 20 had no genetic or structural abnormalities. First trimester CH carries a high risk for genetic abnormalities and adverse outcomes. NT size, early resolution, and cfDNA results are all significant modifiers in the outcomes associated with first trimester CH. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.