Outcomes following the detection of fetal edema in early pregnancy prior to non-invasive prenatal testing

Objective: To investigate the incidence of structural and chromosomal abnormalities in cases of fetal edema on early ultrasound prior to non-invasive prenatal testing (NIPT). Methods: A retrospective study of women undergoing pre-NIPT ultrasound with fetal crown-rump length (CRL) of 28 to 44 mm was conducted at a tertiary obstetric ultrasound clinic in Melbourne, Australia. Cases of reported fetal edema were included, and subclassified as isolated nuchal edema (>2.2 mm) or generalized edema/hydrops by two operators blinded to outcomes. Results: We identified 104 cases of fetal edema. Nuchal edema and generalized edema were present in 40 (38.5%) and 64 (61.5%) cases, respectively. Relevant chromosomal anomalies were identified in 19.2% (20/104), occurring in 10.0% (4/40) of the nuchal edema and 25.0% (16/64) of the generalized edema/hydrops cases. Structural anomalies with normal karyotype occurred in four (3.8%) additional cases. Miscarriage occurred in four cases (3.8%) and termination of pregnancy in 18 cases (17.3%). Among cases that reached the 11 to 13⁺⁶ weeks ultrasound, the edema resolved in 81.9% and these cases had less adverse outcomes than those with NT≥3.5 mm (10.9% vs 76.5%, P <.001). Conclusions: Fetal edema in early pregnancy is associated with a high incidence of structural and/or chromosomal abnormalities; these rates increase with progressive severity.