Society for Maternal-Fetal Medicine (SMFM) Clinical Guideline #7: nonimmune hydrops fetalis

Evaluation of hydrops begins with an antibody screen (indirect Coombs test) to determine if it is nonimmune, detailed sonography of the fetus(es) and placenta, including echocardiography and assessment for fetal arrhythmia, and middle cerebral artery Doppler evaluation for anemia, as well as fetal karyotype and/or chromosomal microarray analysis, regardless of whether a structural fetal anomaly is identified. Recommended treatment depends on the underlying etiology and gestational age; preterm delivery is recommended only for obstetric indications including development of mirror syndrome. Candidates for corticosteroids and antepartum surveillance include those with an idiopathic etiology, an etiology amenable to prenatal or postnatal treatment, and those in whom intervention is planned if fetal deterioration occurs. Such pregnancies should be delivered at a facility with the capability to stabilize and treat critically ill newborns. The prognosis depends on etiology, response to therapy if treatable, and the gestational age at detection and delivery. Aneuploidy confers a poor prognosis, and even in the absence of aneuploidy, neonatal survival is often <50%. Mirror syndrome is a form of severe preeclampsia that may develop in association with fetal hydrops and in most cases necessitates delivery.