What is hydrops fetalis?
Hydrops fetalis — or hydrops — is a condition in which large amounts of fluid build up in a baby’s tissues and organs, causing extensive swelling (edema). Hydrops fetalis is sometimes used as a synonym for homozygous alpha thalassemia, a lethal or life-threatening disease of mid- and late fetal development caused by the inability to make red blood cells. The condition, which can be diagnosed before or after birth, is relatively rare in the United States due to advances in the prevention of hemolytic diseases of the unborn. It can, however, be life threatening. Nearly half of the babies born with hydrops do not survive.
There are two types of hydrops:
- Immune hydrops fetalis, which occurs when the mother’s immune system causes a baby’s red blood cells to break down; this is the most dangerous complication of hemolytic disease of the newborn.
- Non-immune hydrops fetalis, which occurs when disease or other complications interfere with a baby’s ability to manage fluid; this is the most common type of hydrops. Alpha thalassemia major (four gene alpha thalassemia, or homozygous alpha thalassemia) interferes with the fetus’ ability to make red blood cells.
What are the symptoms of hydrops fetalis?
Symptoms of hydrops fetalis can occur during pregnancy or after the baby is born. During pregnancy, symptoms of hydrops fetalis may include:
- large amounts of amniotic fluid
- thickened placenta
- enlarged liver, spleen, or heart in the baby
- fluid buildup in the baby’s abdomen
After birth, symptoms may include:
- pale coloring
- severe swelling overall, especially in the baby's abdomen
- enlarged liver and spleen
- difficulty breathing
What causes hydrops fetalis?
Many different diseases and other medical complications can cause hydrops fetalis, such as:
- hemolytic disease of the newborn
- severe anemia
- infections present at birth
- heart or lung defects
- chromosomal abnormalities and birth defects
- liver disease
How is hydrops fetalis diagnosed?
Hydrops fetalis can be diagnosed during pregnancy or after the baby is born through one of the following tests:
- fetal blood sampling
How is hydrops fetalis treated?
Treatment of hydrops fetalis depends on its cause. During pregnancy, hydrops fetalis is treatable only in certain situations. After birth, treatment may include:
- help for difficulty breathing using extra oxygen or a mechanical breathing machine
- removal of excessive fluid from spaces around the lungs and abdomen using a needle
- medications to help the kidneys remove excess fluid
What is the long-term outlook for hydrops fetalis?
The severe swelling that occurs with hydrops can overtake a baby’s organ systems. About half of unborn babies with hydrops do not survive. For babies born with hydrops, survival often depends on the cause of the disease and its treatment.
How we care for hydrops fetalis
Our Thalassemia Program cares for children with hydrops fetalis. We are one of only six programs designated as centers of excellence in thalassemia by the Cooley’s Anemia Foundation and one of only seven centers sponsored by the federal Centers for Disease Control and Prevention for the prevention of thalassemia complications.