Fetal hydrops

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What is fetal hydrops?

Hydrops fetalis, or hydrops, is defined by the accumulation of abnormal fluid in at least two different fetal compartments. It implies an excess of total body water either under the skin (subcutaneous edema), around the lungs or heart (pleural or pericardial effusions) or in the abdomen (ascites). It may also be associated with an excess of amniotic fluid (polyhydramnios) or a thickened placenta.

Hydrops can be divided in two major categories: immune and non-immune.

Immune hydrops is caused by antibodies developed by Rh-negative blood type mothers being exposed to Rh-positive fetuses. This incompatibility may be prevented if the mother takes RhoGAM during and after pregnancy.

Non-immune causes include:

  • Conditions causing anemia (low blood count) including fetal hemorrhage(bleeding) or alpha-thalassemia (disorder of red blood cell structure)
  • Congenital infections (infections that mother contracts in pregnancy andpasses to baby) such as parvovirus B19 (fifth disease), cytomegalovirus and syphilis
  • Fetal birth defects that affect the heart function (include defect that push theheart or make the heart work harder such as diaphragmatic hernia, cystic adenomatoid malformations, or fetal tumors such as sacrococcygealteratoma) or that affect the heart rhythm (arrhythmias)
  • Genetic syndromes, chromosomal disorders (such as Turner syndrome) or metabolic disorders
  • Twin-twin transfusion syndrome
  • Idiopathic cases (result of an unknown cause)

What is the outcome for a fetus with hydrops?

Fetal hydrops is usually associated with a poor prognosis and can be life-threatening. It might result in a miscarriage, especially if present in early pregnancy.  A few causes are amenable to in utero treatment.

What are the risks involved for the mother?

Mothers of hydropic fetuses are at risk of developing mirror syndrome. This refers to a condition of generalized maternal edema that ‘mirrors’ the edema of the hydropic fetus and placenta. Delivery is usually required to induce remission of maternal symptoms.

Which investigations should we consider?

All patients with fetal hydrops should be referred to a tertiary care centre for evaluation. A detailed ultrasound, fetal echocardiography, blood tests and amniocentesis might be needed.

What therapies are available?

Severely anemic fetuses can have blood transfusions in utero.
Arrhythmias can be treated with medication.
Thoracic malformations can be treated with thoracoamniotic shunt in select cases.
Twin-twin transfusion syndrome can be treated by laser in utero (see TTTS).

Resources

www.Wikipedia.org/Hydrops Fetalis/a>
www.uptodate.com/nonimmunehydropsfetalis
http://emedicine.medscape.com/article/974571-overview
www.perinatology.com/conditions/Hydrops.htm

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