What is Hydrops Fetalis?

Hydrops Fetalis also known as Fetal Hydrops is a condition diagnosed during pregnancy to the unborn baby. This condition is an abnormal collection of fluid in at least two areas.  Hydrops Fetalis is not a disease, it is a symptom of an underlying cause. Even a baby who starts out very healthy baby can develop Hydrops Fetalis from something as simple as an infection.

The areas fluid may collect is:

  • Edema (under the skin)
  • Around the heart (pericardial effusion)
  • In or around the lungs (pleural effusion)
  • The abdominal cavity (ascites)
Hydrops Fetalis is most commonly diagnosed by ultrasound. The ultrasound shows where the fluid is located and other things that may be present (high amount of amniotic fluid, thickened placenta, any visible heart conditions, cystic hygroma, and any enlarged organs commonly the heart, spleen, or liver).

There is two different categories:
Immune Hydrops Fetalis: this is a severe Rh incompatibility. This is when the mother has Rh negative blood and the baby has Rh positive blood.  The mothers body make antibodies against the babies Rh positive blood and these antibodies cross the placenta and cover and destroy the baby's red blood cells. This makes the baby severely anemic.

Non-Immune Hydrops Fetalis: which results makes up more than 90% of cases. This is when the mother does not have negative blood type and the baby positive blood type.  The causes for Non-Immune Hydrops Fetalis are many there are still unknown, but the most common causes are the following...

Starting with the most common causes:
  • Severe Anemia (commonly from congenital infections, fetal hemorrhage or thalassemia) Click Here to view a list of infections
  • Heart defects or lung problems (CCAM ,
  • Chylothorax
  • Chromosomal abnormalities
  • Tumors or other masses (sacrococcygeal teratoma , fetal adrenal neuroblastoma)
  • Problems with the placenta or umbilical cord
  • Twin to Twin transfusion
  • Obstruction to normal lymphatic flow
  • Liver disease
  • Metabolic disorders
  • Congenital nephrosis
  • Defect in the PIEZO1 gene