What is the management approach for a fetus diagnosed with hydrops fetalis?

Management of Hydrops Fetalis

The management of hydrops fetalis requires immediate comprehensive diagnostic evaluation to identify the underlying etiology, followed by etiology-specific fetal therapy when treatable causes are identified, with all cases requiring referral to a tertiary center and careful maternal monitoring for mirror syndrome. 1

Initial Diagnostic Workup

The cornerstone of management is determining whether the hydrops is immune or non-immune, as this fundamentally changes the approach. 1

Mandatory initial investigations include: 1, 2

• Indirect Coombs test to verify non-immune etiology
• Detailed fetal ultrasound with comprehensive echocardiography to identify structural cardiac defects (which account for 17-35% of cases), arrhythmias, and other anatomic abnormalities
• Middle cerebral artery (MCA) Doppler to assess for fetal anemia, with peak systolic velocity >1.5 MoM indicating severe anemia requiring intervention
• Fetal karyotype and/or chromosomal microarray analysis regardless of whether structural anomalies are visible, as chromosomal abnormalities account for 7-16% of cases and confer extremely poor prognosis

Categorization and Counseling

Cases fall into three distinct management categories: 1

1. Treatable etiologies requiring urgent fetal therapy or specialized referral
2. Lethal conditions where pregnancy termination or comfort care are the only realistic options
3. Idiopathic cases with uncertain but likely poor prognosis

Given the overall poor prognosis (often <50% neonatal survival even without aneuploidy), pregnancy termination should be offered if hydrops is identified prior to viability. 1, 2

Etiology-Specific Fetal Interventions

Fetal Arrhythmias

Administer transplacental antiarrhythmic medications for supraventricular tachycardia, atrial flutter, or atrial fibrillation unless gestational age is near term or maternal contraindications exist. 1, 2 Treatable arrhythmias have significantly better prognosis than structural cardiac defects. 1, 3

Fetal Anemia

Perform intrauterine transfusion for confirmed anemia secondary to parvovirus B19 infection or fetomaternal hemorrhage, unless pregnancy is at advanced gestational age where delivery risks are lower than procedural risks. 1, 2 Parvovirus-related hydrops has better outcomes but survivors may have delayed psychomotor development. 1, 3

Pleural Effusions

Drain large unilateral pleural effusions via needle drainage or thoracoamniotic shunt placement for hydrothorax, chylothorax, or effusions associated with bronchopulmonary sequestration. 1, 2 For isolated chylothorax, mortality may be as low as 6%, but rises to two-thirds when associated with other anomalies. 1, 3

Congenital Pulmonary Airway Malformation (CPAM)

• For macrocystic lesions with hydrops: Perform thoracoamniotic shunt placement or needle drainage, which can improve survival to >50%. 4
• For microcystic lesions with hydrops: Administer maternal betamethasone or dexamethasone. 4
• If gestational age ≥34 weeks, consider needle drainage immediately before delivery rather than shunt placement. 4

Twin-Twin Transfusion Syndrome

Refer for laser coagulation of placental anastomoses for TTTS or twin-anemia polycythemia sequence that has resulted in hydrops. 1

Twin-Reversed Arterial Perfusion Sequence

Refer for percutaneous radiofrequency ablation. 1

Obstetric Management Principles

Timing of Delivery

Avoid preterm delivery as prematurity significantly worsens the already poor prognosis. 1, 2 Preterm birth <34 weeks is a significant poor prognostic factor, with younger gestational age, low 5-minute Apgar score, and need for high-frequency ventilation being independent risk factors for death. 1

• Preterm delivery should only be undertaken for obstetric indications. 1
• Continue expectant management if fetal condition is stable and no maternal complications develop. 2
• Deliver by 37-38 weeks in the absence of clinical deterioration or other indications for earlier intervention. 2

Antenatal Corticosteroids

Administer corticosteroids for pregnancies with non-lethal or potentially treatable etiologies that may require preterm delivery. 1, 2

Antepartum Surveillance

Initiate surveillance only when three criteria are met: 2

1. Underlying etiology is not lethal
2. Pregnancy has reached viable gestational age
3. Surveillance findings will guide delivery timing

Mode of Delivery

Perform cesarean delivery if the fetus is potentially treatable or viable and delivery is based on antepartum surveillance findings or concern about fetal deterioration. 2

Delivery Location

All pregnancies with potentially treatable or idiopathic hydrops must deliver at a tertiary center with level-III NICU capability to stabilize and treat critically ill neonates. 1, 2, 3

Maternal Monitoring

Monitor maternal blood pressure serially throughout pregnancy to detect mirror syndrome, which can develop in mothers carrying hydropic fetuses. 1, 2 Mirror syndrome is characterized by preeclampsia-like symptoms and maternal edema that "mirrors" the fetal condition. 2, 3

In most cases, development of mirror syndrome is an indication for delivery. 1, 2

Critical Pitfalls to Avoid

• Do not delay referral to a tertiary center for potentially treatable etiologies—these cases often require urgent specialized intervention. 1
• Do not assume infectious workup is negative based solely on laboratory results if clinical history is strongly suggestive of infection. 5
• Do not overlook maternal autoantibodies (particularly Anti-Ro/SSA in Sjögren's syndrome) as a cause of fetal anemia and hydrops. 5
• Do not deliver prematurely without clear indication, as prematurity compounds the already poor prognosis. 1, 2
• Do not underestimate the risk of mirror syndrome—serial maternal blood pressure monitoring is essential. 1, 2

Prognostic Considerations

Overall mortality remains high despite advances in fetal therapy, with no significant improvement in survival over the past two decades (47-67% mortality). 1 Prognosis varies dramatically by etiology: 1, 3

• Cardiac structural abnormalities: 92% combined fetal and infant mortality
• Chromosomal abnormalities: Extremely poor prognosis with very high rates of intrauterine fetal death
• Isolated chylothorax: 6% mortality when isolated
• Treatable arrhythmias and parvovirus B19: Better prognosis with appropriate intervention

Aneuploidy confers extremely poor prognosis and should prompt counseling about pregnancy termination or comfort care. 2, 3