Perinatal Outcomes of Cystic Hygroma: A Systematic Review and Meta-Analysis: Running Head: Systematic Review of Cystic Hygroma Outcomes.

Abstract

Objectives: The aim of this systematic review and meta-analysis was to describe the perinatal outcomes and modifiers of antenatally diagnosed cystic hygroma (CH).

Data sources: The PubMed, Embase and Web of Science Core Collection databases were searched from inception until March 18, 2024.

Study eligibility criteria: Full-text English-language observational cohort studies reporting any pregnancy and postnatal outcomes for fetuses with a CH diagnosed on prenatal ultrasound were included in this study.

Methods: The primary outcome was the incidence of genetic diagnosis and incidence of major structural anomalies. Secondary outcomes included the incidence of perinatal loss, termination of pregnancy, CH resolution, live birth rate and normal postnatal outcomes. Stratified analyses were conducted of cases diagnosed in the first trimester as well as all cases with septations as part of diagnostic criteria. Pooled proportions were calculated for the different outcomes.

Results: Fifty-seven studies met inclusion criteria (including 4693 cases of CH); these were cohort studies that included any of our primary search outcomes. The pooled prevalence of genetic diagnosis (56 studies, 3837 fetuses) was 55% (95% CI, 0.51-0.58). For specific aneuploidies, the pooled prevalence was 21% for Turner syndrome, 17% for Trisomy 21, 10% for Trisomy 18, 3% for Trisomy 13, and 5% for other genetic diagnoses. The overall pooled prevalence of major structural anomalies (30 studies, 1987 fetuses) was 42%; across 16 studies (1815 fetuses), 16% of fetuses with CH and an additional structural abnormality had no identified genetic diagnosis. Furthermore, 20% of all CH regressed or resolved during the pregnancy. The findings from the studies that that defined CH by the presence of septations, as well as those focusing solely on first trimester CH were consistent with the overall outcomes.

Conclusions: Our findings confirm that while CHs have a strong association with common trisomies and Turner syndrome, there is a proportion of cases with non-aneuploidy genetic diagnoses. Forty percent of cases are also associated with other structural anomalies that may be able to be elicited with a detailed first trimester anatomic ultrasound. Further studies should explore modifiers of CH outcomes to allow for more accurate and tailored patient counseling.