Hydrops fetalis is a complication of severe anemia, which is most often caused by alloimmunization or hemolytic disease of the fetus and newborn (HDFN). Hydrops fetalis is rare, but it can have life-threatening consequences if not treated urgently.
TSevere hydrops fetalis can put strain on the heart, which can cause accumulation of fluid in the tissue and organs, as well as swelling around the heart, lungs and abdomen. Around 50% of unborn babies with hydrops fetalis don’t survive, so urgent treatment and sometimes a preterm delivery are required to ensure the best outcomes for the baby.
What is HDFN?
Hemolytic disease of the fetus and newborn (HDFN) is an immune-mediated red blood cell disorder that occurs when a baby’s RBCs break down quickly, which is called hemolysis. HDFN is caused by a mismatch between a mother’s and her baby’s blood type (A, B, AB, or O) or Rhesus (Rh) factor (Rh-positive or Rh-negative) during pregnancy.
How does hydrops fetalis occur?
In HDFN, maternal antibodies cross the placenta to attack the fetus’s red blood cells. As the red blood cells break down, anemia develops. If this leads to severe anemia, strain is put on the fetus’s heart as it struggles to pump oxygen-rich blood around the body and less oxygen is delivered to the body’s tissues and organs, causing damage and leading to heart failure.
During heart failure, fluid accumulates around the heart, lungs and abdomen. It also gathers in the skin, causing edema or swelling.
What are the risks of hydrops fetalis?
When severe anemia is detected, urgent treatment is required to avoid serious complications such as hydrops fetalis. Without effective treatment or early delivery to allow for urgent medical intervention, hydrops fetalis can, in some cases, lead to cardiac arrest, fetal death or a miscarriage during pregnancy.
Following delivery, a newborn affected by hydrops fetalis can experience respiratory distress, feeding difficulties, brain damage, developmental delays and cerebral palsy. Urgent intervention after birth is necessary to ease breathing difficulties with a ventilator or extra oxygen and to remove extra fluid around the heart and lungs with a needle.
Read more about HDFN causes and risk factors
Diagnosing hydrops fetalis in pregnancy
Fetal anemia is detected via MCA Doppler, which measures blood flow velocity in the fetal brain’s middle cerebral artery. Hydrops fetalis is detected via ultrasound when swelling is identified.
Treating hydrops fetalis in HDFN
Early diagnosis of anemia and proactive treatment with intrauterine transfusions and intravenous immunoglobulin during pregnancy can delay or prevent the onset of severe anemia and the complication of hydrops fetalis.
Early delivery may be required to remove the baby from the effects of the maternal antibodies and to allow for urgent treatment to resolve hydrops fetalis.
Sign up here to get the latest news, perspectives, and information about HDFN sent directly to your inbox. Registration is free and only takes a minute.
