• Hydrops Fetalis Overview

    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 breakdown; 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.

    Hydrops Fetalis Treatment at Dana-Farber/Boston Children's

    Continue reading to learn more about hydrops fetalis or visit the Thalassemia Program homepage to learn about our expertise and treatment approach for this condition.

    Symptoms & Diagnosis

    Symptoms of hydrops can occur during pregnancy or after birth. Symptoms during pregnancy include:

    • Large amounts of amniotic fluid
    • Thickened placenta
    • Enlarged liver, spleen and heart in the baby
    • Fluid buildup in the baby’s abdomen

    Symptoms after birth include:

    • Pale coloring
    • Severe swelling, especially in the abdomen
    • Enlarged liver and spleen
    • Difficulty breathing

    Hydrops fetalis can be diagnosed during pregnancy or after delivery through an ultrasound, fetal blood sampling and amniocentesis.

    Treatment & Care

    Treatment of hydrops depends on the cause of the condition. In certain situations, the condition may be treatable during pregnancy. In homozygous alpha thalassemia, transfusions in utero may be life-saving. After birth, treatments may include using extra oxygen or a mechanical breathing machine to help a baby breath; removal of excess fluid from spaces around the lungs and abdomen; and medications to help the kidneys remove excess fluid.

    Long-term Outlook

    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.
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