First-trimester septated cystic hygroma - Prevalence, natural history, and pediatric outcome

Objective: To estimate prevalence, natural history, and outcome of septated cystic hygroma in the first trimester in the general obstetric population, and to differentiate. this finding from simple increased nuchal translucency. Methods: Patients at 10.3-13.6 weeks of gestation underwent nuchal translucency sonography as part of a multicenter clinical trial. Septated cystic hygroma cases were offered chorionic villi sampling for karyotype, and targeted fetal anatomical and cardiac evaluations. Survivors were followed up for fetal and long-term pediatric outcome (median 2 months, range 12-50 months). Cases of septated cystic hygroma were also compared with cases of simple increased nuchal translucency. Results: There were 134 cases of cystic hygroma (2 lost to follow-up) among 38,167 screened patients (1 in 285). Chromosomal abnormalities were diagnosed in 67 (51%), including 25 trisomy-21, 19 Turner syndrome, 13 trisomy-18, and 10 others. Major structural fetal malformations (primarily cardiac and skeletal) were diagnosed in 22 of the remaining 65 cases (34%). There were 5 cases (8%) of fetal death and 15 cases of elective pregnancy termination without evidence of abnormality. One of 23 (4%) normal survivors was diagnosed with cerebral palsy and developmental delay. Overall, survival with normal pediatric outcome was confirmed in 17% of cases (22 of 132). Compared with simple increased nuchal translucency, cystic hygroma has 5-fold, 12-fold, and 6-fold increased risk of aneuploidy, cardiac malformation, and perinatal death, respectively. Conclusion: First-trimester cystic hygroma was a frequent finding in a general obstetric screening program. It has the strongest prenatal association with aneuploidy described to date; with significantly worse outcome compared with simple increased nuchal translucency. Most pregnancies with normal evaluation at the completion of the second trimester resulted in a healthy infant with a normal pediatric outcome.