Hydrops Fetalis

Hydrops fetalis, or hydrops, is a condition where fluid builds up in a fetus’s tissues and organs, causing swelling (edema). Although rare, hydrops can be life-threatening, as the fluid buildup can impact the function of vital organs such as the heart, lungs, liver, and kidneys.

There are two types of hydrops fetalis:

• Immune hydrops fetalis occurs when there is a blood-type incompatibility between the pregnant person and the fetus, a condition known as hemolytic disease of the fetus or newborn (HDFN). The most common cause of immune hydrops fetalis is Rh incompatibility, which happens when the pregnant person has Rh-negative blood and the fetus has Rh-positive blood. In this situation, the pregnant person’s immune system may see the fetus’s Rh-positive blood cells as foreign and attack them. This can lead to fetal anemia, which, if severe, may cause heart failure and dangerous fluid buildup.
• Non-immune hydrops fetalis can be caused by a variety of factors, including genetic disorders, cardiac structural anomaly or arrythmia, infection, complications in a twin pregnancy with shared placenta, congenital structural anomalies, and fetal or placental tumors.

Boston Children’s Fetal Care and Surgery Center is a national leader in managing and treating hydrops in pregnancy and after birth. We provide innovative genetic and genomic testing, state-of-the-art fetal imaging, and multidisciplinary, comprehensive care and fetal intervention if indicated.

In most cases, hydrops fetalis does not cause symptoms in the pregnant person and is usually found during fetal imaging. Occasionally however, the following symptoms may occur:

• Decreased fetal movement
• Excessive amniotic fluid, which can cause shortness of breath (dyspnea) or contractions
• Mirror syndrome that can present with maternal leg edema, pulmonary edema, pain in the upper abdomen, headache, and in some cases, eclampsia

Mirror syndrome that can present with maternal leg edema , pulmonary edema, pain in the upper abdomen, headache, and in some cases, eclampsia.

Immune hydrops is caused by blood-type incompatibility between the pregnant person and the fetus (also known as hemolytic disease of the newborn (HDN)). Non-immune hydrops fetalis can be caused by several conditions, including:

• Severe fetal anemia unrelated to HDFN
• Infections present at birth
• Abnormal heart rhythms
• Heart defects or lung defects
• Skeletal disorders
• Birth defects and congenital anomalies
• Metabolic disorders
• Genetic conditions
• Fetal or placental tumors

Hydrops fetalis can be evaluated through various tests during pregnancy, including:

• Prenatal ultrasound
• Fetal MRI
• Fetal blood sampling
• Fetal echocardiography
• Amniocentesis

Treatment for hydrops fetalis depends on its underlying cause. Managing hydrops during pregnancy can be challenging, and in some cases, fetal surgery may be needed to reverse the condition or prevent it from getting worse. In other cases, an early delivery may be recommended. After delivery, care may include:

• Extra oxygen or mechanical ventilation for breathing support
• Using a needle to drain excessive fluid from the lungs or abdomen
• Medication to help the kidneys remove excess fluid

The severe swelling associated with hydrops can overwhelm multiple organs, making it a life-threatening condition. However, the chances of survival can be greatly improved with the right treatment, depending on the specific cause and timely intervention.

The Fetal Care and Surgery Center brings together experts in maternal-fetal medicine, genetics, radiology, neonatology, fetal surgery, and other areas to provide comprehensive care for hydrops fetalis during and after pregnancy. We focus on early and accurate diagnosis, advanced treatment options, and personalized care plans tailored to each patient. This means access to cutting-edge care from a dedicated team of experts working together to achieve the best possible outcomes.

Our team-based approach and commitment to research and innovation ensure that every family receives the highest level of care and support.