From the Guidelines
Differentiating and managing immune versus non-immune hydrops fetalis requires a systematic approach based on the underlying cause, with non-immune hydrops accounting for approximately 90% of cases and requiring identification of the specific etiology through comprehensive evaluation, as recommended by the Society for Maternal-Fetal Medicine 1. To differentiate between immune and non-immune hydrops fetalis, a thorough maternal history including blood type, antibody screening, and previous pregnancies should be obtained to identify potential alloimmunization.
- Perform detailed ultrasound assessment to evaluate for fetal anemia through middle cerebral artery peak systolic velocity measurements, with values >1.5 MoM suggesting significant anemia requiring intervention.
- For non-immune hydrops, management is directed at the underlying cause, such as antiarrhythmic medications for cardiac arrhythmias, thoracocentesis or thoracoamniotic shunting for pleural effusions, or specific treatments for identified infections, as outlined in the SMFM clinical guideline 1.
- The initial evaluation of hydrops should include an antibody screen to verify that it is nonimmune, targeted sonography with echocardiography, MCA Doppler evaluation for anemia, and fetal karyotype or chromosomal microarray analysis, regardless of whether structural fetal anomalies are identified, as recommended by the SMFM 1. Key considerations in managing non-immune hydrops fetalis include:
- Identification of the underlying etiology through comprehensive evaluation, including detailed ultrasound, fetal echocardiography, amniocentesis for karyotype and viral studies, and maternal testing for infections, metabolic disorders, and hemoglobinopathies.
- Treatment decisions based on the underlying etiology, gestational age, and presence of treatable causes, with preterm delivery recommended only for obstetric indications, including development of mirror syndrome 1.
- Pregnancies with non-immune hydrops fetalis due to nonlethal or potentially treatable etiologies should be considered candidates for corticosteroid therapy and antepartum surveillance, and delivered at a center with capability to stabilize and treat critically ill neonates, as recommended by the SMFM 1.
From the Research
Differentiation between Immune and Non-Immune Hydrops Fetalis
- Immune hydrops fetalis is typically caused by rhesus isoimmunization, as seen in a study where fetal intravascular transfusion was used to manage hydropic disease due to rhesus isoimmunization 2.
- Non-immune hydrops fetalis (NIHF) accounts for more than 90% of hydrops cases in the Western world and is caused by an imbalance in the regulation of fetal fluid movement between the vascular and interstitial space 3.
- NIHF can be caused by a wide range of genetic and non-genetic factors, including congenital syphilis, as reported in a case where intrauterine transfusion was successfully used to manage non-immune hydrops fetalis secondary to congenital syphilis 4.
Management of Immune Hydrops Fetalis
- Fetal intravascular transfusion can be an effective management strategy for immune hydrops fetalis, with a study showing a survival rate of 88.9% for hydropic fetuses managed with this approach 2.
- The goal of management is often to deliver the fetus by cesarean section beyond 33 weeks of gestation, with all patients receiving prophylactic antibiotics and ritodrine for 4 days after the procedure 2.
Management of Non-Immune Hydrops Fetalis
- A systematic approach to evaluation is essential to determine the underlying etiology of NIHF, including prenatal ultrasound findings, genetic testing, and family and obstetric history 5.
- Intrauterine transfusion can be a successful management strategy for NIHF, as seen in a case where it was used to manage non-immune hydrops fetalis secondary to congenital syphilis 4.
- Genetic testing, such as chromosomal microarray or whole exome sequencing, can be used to identify the underlying genetic cause of NIHF, guiding a more targeted approach to management 5.