Hydrops fetalis

DEFINITION

Abnormal accumulation of fluid in ≥2 compartments of the fetus (pleural and pericardial effusions, ascites and/or subcutaneous oedema)
Often associated with polycythaemia and placental thickening
High but variable mortality rates dependent on underlying cause

Traditionally classified into 2 types:
- non-immune hydrops fetalis occurs in the absence of maternal antibodies; accounts for 90% of fetal hydrops in Western countries
- immune hydrops fetalis occurs when maternal allo-immune antibodies are produced against fetal red cells causing haemolysis; rare since introduction of anti-D immunoglobulins

Imbalance of fluid movement between fetal intravascular and interstitial spaces
Multiple causes including cardiac abnormalities (structural or arrhythmias), chromosomal/ genetic, infection, haematological, metabolic and non-cardiac structural anomalies
No identifiable cause found in 15–31% of babies

Hydrops fetalis is diagnosed antenatally via ultrasound
Refer to fetal medicine team [important as confirmed antenatal diagnosis aids appropriate counselling of families, and further intensive monitoring required throughout pregnancy (discussion of this is beyond the scope of this guideline)]
Possible antenatal interventions include intra-uterine blood transfusion and in-utero procedures e.g. paracentesis/thoracentesis
High risk of premature delivery

Refer all antenatally diagnosed hydrops fetalis to a regional fetal medicine centre for further assessment and management

Consider concurrent pleural/ascitic drains to facilitate resuscitation

Give only CMV negative and irradiated blood

Ensure adequate oxygenation and ventilation
May require high frequency oscillatory ventilation [see Ventilation: high frequency oscillatory ventilation (HFOV) guideline and muscle relaxation
If pulmonary hypertension present may require nitric oxide (see Nitric oxide guideline)

Use inotropes to support heart and blood pressure
If intravascular fluid depletion give colloid
Strict fluid balance
If severe compromise may require further pleural and ascitic taps
Immune hydrops may require exchange transfusion. See Jaundice and Exchange transfusion guidelines

Due to the extensive list of potential causes, direct investigations according to clinical history and presentation
Initial investigations to consider include:

	Initial investigations	Further investigations to be considered if underlying cause is not ascertained
Haematology	FBC (including blood film) Group and direct Coombs test Maternal Kleihauer test	Red cell enzyme deficiency (e.g. G6PD deficiency) Red cell membrane defects (e.g. hereditary spherocytosis) Haemoglobinopathies (e.g. thalassaemia)
Biochemistry	Liver function tests including albumin Urea, creatinine and electrolytes	If pleural/ascitic tap done – send for fluid MC+S and biochemistry
Cardiac	ECG to exclude cardiac dysrhythmias Echocardiography to exclude structural heart defects
Placenta	Send to pathologist
Genetic testing	Chromosomes Microarray	Investigate for congenital metabolic conditions Non-immune hydrops − discuss whole exome sequencing with genetics team
Infection	Toxoplasma, rubella, CMV, parvovirus, herpes simplex virus
Radiology	Chest X-ray Abdominal X-ray Cranial ultrasound scan	Further investigations to be guided by clinical picture

Even with optimal management, the mortality rate is high. Suggest a post-mortem in the event of a death

See Guideline Supporting Information

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