Hydrops fetalis

Overview

Immune hydrops fetalis is caused by red blood cell alloimmunisation haemolytic disease. All other causes are described as non-immune hydrops fetalis (NIHF). Hydrops is a symptom of a wide range of conditions which have resulted in an imbalance in fetal fluid between the vascular and interstitial space.¹

Diagnostic criteria are fluid in at least two body cavities (pleural space, pericardial space, peritoneal space, skin or placental enlargement). The prognosis depends on associated prematurity, the underlying cause, the severity of any associated pulmonary hypoplasia and the severity of the ongoing post-natal fluid accumulation (with problems of infection and malnutrition).²

Studies have found a perinatal mortality rate of up to 57%.³,⁴,⁵Mortality and morbidity appears dependent on cause and gestational age at diagnosis. There is high risk for premature delivery. Neonatal mortality remains high at 35% with an overall mortality of 43% at one year. There is one retrospective review reporting normal developmental outcome in half of 56 cases followed-up at one year and is more likely when NIHF is associated with tachyarrhythmia, congenital chylothorax, meconium peritonitis and parvovirus.⁴

Resuscitation

Any baby known to have NIHF should be delivered at a tertiary centre. Find out about the size of pleural effusions and severity of the hydrops from obstetric staff before delivery. It is important to prepare equipment before delivery. Resuscitation and stabilisation is often difficult. The level III specialist should be informed and may well need to attend the delivery. A senior neonatal nurse should also attend. It may be necessary to drain pleural effusions or ascites in the delivery room, at the same time as resuscitating the baby.

Associations with Non-Immune Hydrops

There is a long list of possible causes of NIHF - see table below.

Half of the reported causes of NIHF comprise of cardiovascular anomalies/arrhythmias (21.4%), chromosomal abnormalities (12.5%) or are idiopathic - unexplained (18.2%).⁶

The images to the right demonstrate an infant with hydrops - in this case bilateral pleural effusions, ascites and oedema. The cause of this baby's hydrops was thought to be a congenital chylothorax. Baby was managed with dietary maniuplation using Monogen, without re-accumulation of pleural effusions. Baby was changed to breast feeding uneventfully at three weeks of age.

Congenital Chylothorax

Lymphatic dysplasia, predominantly seen as chylothorax, contributes up to 15% of NIHF cases.⁶,⁷ The pleural fluid is serous until milk feeding begins and it turns chylous. Diagnosis is based on a high lymphocyte presence and protein concentration in the pleural fluid, in addition triglyceride and lipoproteins are present with feeding.

There is a risk of loss of anticoagulant factors and immunoglobulins along with malnutrition. Medium chain triglycerides are absorbed directly into the portal vein, bypassing lymphatic drainage. Enteral feeds are usually started with an MCT based formula while waiting for the chylous leakage to improve. The usual clinical course may take longer than 4 weeks to resolve. Note - MCT formulas do not contain essential fatty acids and may need supplementing if used for an extended period.

Evidence for the use of octreotide is based on collective case reports with a range of success.⁸There is no standard treatment recommendation for the use of octreotide although it appears to be safe in neonates.⁹⁻¹²

Pathophysiological mechanism of NIHF

(Adapted from reference Bellini 2012)

Investigations

Many of these may have been done antenatally. Particular clinical findings may indicate other investigations for aetiology. Target investigations at clinical features. Collect cord blood EDTA and clotted samples.

Infective causes

Look for supportive evidence with long bone X-rays, cerebral US/CT and ophthalmic exam.

This list is not comprehensive! Also it does not give an idea of how common conditions may be.