Cardiac

20%

Fetal arrhythmias (bradyarrhythmias and tachyarrhythmias)

Structural cardiac defects causing congestive failure

Extrinsic compression of heart causing low output states → leads to fetal tachyarrhythmia → high-output failure → hydrops

Myocarditis

Renal

5%

Nephrosis

Renal hypoplasia/aplasia

Renal vein thrombosis

Obstructive uropathies

Infection

8%

Toxoplasmosis

Herpes simplex virus

Syphilis

Adenovirus

Rubella

CMV

Hepatitis

Parvovirus

Pulmonary

5%

Congenital chylothorax

Pulmonary lymphangiectasia

Congenital diaphragmatic hernia

Cystic adenomatoid malformations

Other intrathoracic masses (eg, pulmonary sequestration) that cause compression of thoracic blood vessels → obstructive venous flow → hydrops

Placenta/cord

Rare

Chorangioma

Arteriovenous malformation

Significant cord compression

Umbilical vein thrombosis

True umbilical cord knot

Maternal conditions

5%

Diabetes mellitus

Severe preeclampsia/ eclampsia

Hyperthyroidism

Gastrointestinal

5%

In utero midgut volvulus

Bowel atresias

Chromosomal

10%

Turner syndrome

Aneuploidy

Trisomies 13, 18, 21

Noonan Syndrome

Miscellaneous

10%

Congenital myopathies

Inborn errors of metabolism

CNS malformations

Skeletal dysplasias

Abdominal neoplasms

Unknown

20%

Pulmonary

• Difficult intubation due to severe edema of head/neck/oropharynx. → Consider ENT or anesthesia support for intubation as needed.
  
• Varying degrees of pulmonary hypoplasia due to large pleural effusions or other extrinsic in utero compression of lungs → May need emergent thoracentesis in delivery area to alleviate lung compression from large effusions.
  
• Chest tube placement for rapidly reaccumulating pleural effusions.

Cardiovascular

• Hypotension should be treated with appropriate inotropic support.
  
• Remember that most hydropic infants are euvolemic intravascularly, often with depressed cardiac function → Avoid large fluid shifts.
  
• Pericardiocentesis may be necessary if cardiac tamponade from pericardial effusion is suspected → Should ideally be done under US guidance.
  
• Arterial access is helpful to follow invasive blood pressures.
  
• Echocardiogram should be obtained to evaluate for structural abnormalities as a cause of hydrops.

Fluids and electrolytes

• Infants are total body fluid overloaded but are usually euvolemic (intravascular status).
  
• Fluid intake should be based on a “dry” weight (ie, the 50th percentile for gestational age).
  
• Fluids should be restricted (40–60 mL/kg/day) to avoid further fluid overload and to allow diuresis.

• Vigilant attention to all fluid intake and output to maintain an adequate circulating volume.
  
• Electrolyte losses should be replaced accordingly in the IV fluids.
  
• Diuretics should be used very judiciously.
  
• Abdominal US should be obtained to evaluate for an intra-abdominal mass/process that is compressing the IVC and other vascular structures.

Hematology

• For infants who are very anemic (hematocrit <30%), an isovolumetric partial volume exchange transfusion should be done to raise the hematocrit to ∼40%–50% (see Chapter 37).
  
• For management of immune-mediated disease, please refer to Chapter 37 for further discussion.

Infectious disease

• Workup should proceed as indicated to find infectious etiologies for the infant’s hydrops.
  
• Serum PCR can be sent to find evidence of a multitude of viral pathogens (enteroviruses, parvovirus, adenovirus, rubella).
  
• Blood sample for viral cultures (for herpes simplex virus, CMV antigenemia).
  
• Urine for CMV culture.
  
• Serologies for bacterial or other pathogens as indicated.

Renal

• Renal US to evaluate for intrinsic renal disease/obstructive uropathy as a cause of hydrops.
  
• The role of ultrafiltration has not been established in the treatment of fluid overload found in hydropic infants, especially as the edema is known to improve with very careful monitoring of total fluid intake and output.