What is hydrops fetalis?

Hydrop fetalis (HIGH-drops fee-TAH-lis) is a life-threatening condition in which abnormal amounts of fluid accumulate in two or more body areas of an unborn baby. Although the fluid buildup may appear anywhere in the baby’s body, it most often occurs in the abdomen, around the heart or lungs, or under the skin. Other symptoms of the condition include higher-than-normal amounts of amniotic fluid (polyhydramnios) and a thickening of the placenta.

Hydrop fetalis is not a disease, but a symptom of an underlying health problem with the baby. If untreated, the excess fluid can stress the baby’s heart and other vital organs, putting the baby’s life at risk.

There are two types of hydrops fetalis:

  • Non-immune hydrops. This type of hydrops fetalis accounts for approximately 80 percent to 90 percent of all cases of the condition. It occurs when an underlying disease, genetic disorder or birth defect interferes with the ability of the baby’s body to manage fluid.
  • Immune hydrops. This type of hydrops fetalis occurs when there is an incompatibility between the red blood cells of the mother and baby. The most common example is when a pregnant woman has Rh-negative blood and her unborn baby has Rh-positive blood (known as Rh incompatibility). The mother’s immune system treats the baby’s Rh-positive red blood cells as “foreign invaders,” and sends out antibodies to fight them. This leads to the destruction of many of the baby’s red blood cells, an outcome that causes anemia. Severe anemia in the baby can lead to heart failure and an abnormal buildup of fluid. Most cases of red blood cell incompatibility create only mild to moderate health problems for the baby. In about one in four cases, however, the situation becomes more serious and leads to the development of hydrops fetalis.

Since the 1960s, the incidence of immune hydrops has fallen significantly due to the introduction of a medicine called RhoGAM. The drug, which is given to women whose pregnancies are at risk of Rh incompatibility, keeps the mother’s body from making antibodies against her baby’s red blood cells.

Who will be on my care team?

At Midwest Fetal Care Center, a collaboration between Children’s Minnesota and Allina Health, we specialize in individual attention that starts with you having your own personal care coordinator to help you navigate your baby’s treatment process. We use a comprehensive team approach to hydrops fetalis and any associated anomalies. That way, you are assured of getting the best possible information by some of the most experienced physicians in the country. For hydrops fetalis, your care team will include a maternal-fetal specialist, a pediatric cardiologist, a neonatologist, a geneticist, a nurse specialist care coordinator, a perinatal social worker and several other technical specialists.  Your care team may also include a pediatric surgeon or other pediatric specialists, depending on the cause of hydrops. This entire team will follow you and your baby closely through the evaluation process, and will be responsible for designing and carrying out your complete care plan.

Meet the team

What causes hydrops fetalis?

Non-immune hydrops has many possible causes, including the following:

  • Birth defects that affect how the heart functions, such as a heart defect or an arrhythmia (an abnormal heart beat or beating pattern), or a tumor that compress the heart or the blood flow to the heart
  • A hemoglobin abnormality or other genetic disorder that causes the baby’s blood cells to be destroyed
  • Chromosomal disorders, such as Down’s syndrome (trisomy 21) or Turner syndrome
  • Congenital infections (ones passed from the mother to the baby before birth), including parovirus B19 (fifth disease) and cytomegalovirus (CMV)
  • Liver disease
  • Tumors with a large amount of blood flow
  • A monochorionic pregnancy (in which two or more genetically identical babies share the same placenta)
  • Fetal anemia due to non-immune causes, including several of the conditions listed above, as well as bleeding in the mother’s abdomen, sometimes caused by trauma

In some cases, however, there is no identifiable reason for non-immune hydrops to appear.

Immune hydrops is caused by an incompatibility of red blood cells between the mother and her unborn baby. That incompatibility leads to the destruction of a large number of the baby’s red blood cells (also known as hemolytic disease). As the baby’s body tries to make new red blood cells and the heart works harder, excess fluid can form and fill spaces around the baby’s heart, lungs and other organs.

How is hydrops fetalis diagnosed?

Hydrop fetalis is often diagnosed during a routine prenatal ultrasound exam. In some cases, however, your doctor may order an ultrasound to specifically check for the condition. This may happen if your unborn baby’s movements decrease significantly, if the uterus measures large for the baby’s gestational age (the number of weeks the baby has been in the uterus) or if the mother develops early onset preeclampsia (high blood pressure during pregnancy). If there is a known risk due to maternal red cell antibodies (red blood cell incompatibility), routine ultrasound exams will be recommended to screen for fetal anemia and hydrops.

The diagnosis of hydrop fetalis will be made if the ultrasound reveals abnormal amounts of fluid in two or more areas of your baby’s body. The ultrasound may also reveal other signs associated with hydrop fetalis, including a large amount of amniotic fluid, a thickened placenta, and an enlarged heart, liver or spleen.

To distinguish non-immune from immune hydrops, the mother’s blood will be tested for the presence of antibodies associated with red blood cell incompatibility.

How is hydrops fetalis managed before birth?

The prenatal management of babies with hydrops fetalis starts with acquiring as much information about the condition’s severity and underlying cause as early as possible. A thorough history of the mother’s health will be obtained to screen for infections or other possible factors related to the mother’s health that can lead to fetal anemia and hydrops fetalis. We will also gather information through the use of several different technologies, including high-resolution fetal ultrasonography, fetal echocardiography and amniocentesis.

What is high-resolution fetal ultrasonography?

High-resolution fetal ultrasonography is a non-invasive test performed by one of our ultrasound specialists. The test uses reflected sound waves to create images of your baby within the womb. We will use ultrasonography to identify possible birth defects related to hydrops fetalis, as well as to follow the development of your baby’s internal organs and overall growth throughout the pregnancy. The test will also allow us to keep track of the amount of amniotic fluid surrounding your baby, as well as how well blood is flowing through the umbilical cord and within your baby’s other blood vessels. Blood flow within the middle cerebral artery (MCA) in the brain will help us to determine if there is evidence of fetal anemia.

What is fetal echocardiography?

Fetal echocardiography (“echo” for short) is performed at our center by a pediatric cardiologist (a physician who specializes in fetal heart abnormalities). This non-invasive, high-resolution ultrasound procedure looks specifically at how your baby’s heart is structured and how well it is functioning within the womb.

What is amniocentesis?

An amniocentesis is done to sample the amniotic fluid around your baby. This fluid will contain some of your baby’s cells, which will provide a full set of your baby’s chromosomes for us to analyze. We can then assess if the cause of the hydrops fetalis is related to a genetic or chromosomal abnormality. The amniotic fluid may also be assessed for infection or liver/metabolic disease — if there is suspicion that these are the possible causes. The amniocentesis procedure is straightforward and can be done in our clinic. It requires placing a small needle through the mother’s abdomen and into the amniotic sac to obtain the fluid sample. Getting final results from the test from our laboratory usually takes several days. The information will be very important for creating your care plan and helping the neonatologist care for your infant after birth.

What happens after my evaluation is complete?

After we have gathered all the anatomic and diagnostic information from the tests, our full team will meet with you to discuss the results and any treatment possibilities. Treatment will depend on several factors, including the cause of your baby’s hydrops fetalis, the extent of the condition and your baby’s gestational age.

If the suspected cause of the condition is a loss of red blood cells (fetal anemia), your doctor may recommend percutaneous umbilical cord blood sampling (PUBS), also called cordocentesis. A very thin needle will be used to draw a sample of your baby’s red blood cells from the umbilical cord. If the red blood cell count is low, an intrauterine fetal blood transfusion may be recommended. This procedure, which is similar to amniocentesis, injects red blood cells from a compatible donor into the baby’s umbilical cord.

In rare cases of tumor-caused hydrops fetalis, the possibility of prenatal surgery to remove the tumor may be discussed.

Prenatal surgery may also be discussed in cases of complicated monochorionic twin pregnancies.

If your baby has a cardiac arrhythmia, your doctor may recommend a medication to help regulate the baby’s heartbeat. The medication will be given to the mother and then passed through the placenta to the baby.

Excess fluid within the baby can sometimes be removed prenatally during a single procedure with a needle, or a shunt can be placed to continuously drain the fluid. For example, if there is fluid collecting around the baby’s lungs, a small curled tube can be inserted into the chest to drain the fluid into the amniotic cavity. This treatment resolves the pressure against the baby’s heart and lungs.

Often, however, hydrops fetalis can’t be treated during pregnancy. In such cases, we will monitor both mother and baby carefully throughout the pregnancy, looking for any developments that might necessitate an early delivery. Depending on the gestational age, we may recommend biophysical profile studies (BPPs) to evaluate the baby’s wellbeing.  During this test, a heart-rate monitor is placed on the mother’s abdomen to observe the baby’s heart rate pattern in addition to an ultrasound exam evaluating the baby’s movements. Your doctor will use the test, which can last for up to 30 minutes, to determine if your baby is receiving enough oxygen from the placenta. The test also helps to assess the amount of amniotic fluid surrounding the baby.

Our goal is to get your baby as close to the due date as possible, since early delivery can be life-threatening for the baby. The parents’ wishes will be considered when discussing delivery timing and intervention. Regardless of any potential treatment, hydrops fetalis is a serious condition and there is a chance the baby will not survive the pregnancy or after delivery.

Immediate delivery of a baby with hydrops fetalis is sometimes needed to protect the health of the mother. Women whose babies have hydrops fetalis are at increased risk of developing a potentially life-threatening form of pregnancy-related high blood pressure known as “mirror syndrome.” (It’s called that because the mother’s symptoms mirror the fluid buildup in the baby.) The only treatment for mirror syndrome is to deliver the baby.

How is hydrops fetalis treated after birth?

Our goal will be to have your baby’s birth occur as near to your due date as possible, but infants with hydrops fetalis must often be delivered early. Delivery is frequently by cesarean section because there is an increased risk the baby will not tolerate labor and delivery. Your baby will be born at The Mother Baby Center at Abbott Northwestern and Children’s Minnesota in Minneapolis or at The Mother Baby Center at United and Children’s Minnesota in St. Paul. Children’s Minnesota is one of only a few centers nationwide with a birth center located within the hospital complex. This means that your baby will be born just a few feet down the hall from our newborn intensive care unit (NICU). Also, many of the physicians you have already met will be present during or immediately after your baby’s birth to help care for your baby right away.

Your baby will need specialized medical care after birth and will therefore be taken to our NICU. A mechanical breathing machine (ventilator) may be used to help your baby breathe, and a needle may be used to remove fluid from the spaces around the heart, lungs and abdomen. Your baby will also be placed on special intravenous (IV) lines for the delivery of needed nutrients and medications. The medicines are likely to include ones to keep the heart functioning and to help the kidneys remove excess fluid from the baby’s body. If your baby has immune hydrops, he or she may receive an exchange transfusion of red blood cells.

Our goal will be to make a definitive diagnosis of the underlying cause of the hydrops fetalis as quickly as possible. To make that diagnosis, further tests will be done soon after birth.

Will my baby need an operation?

Your baby may need an operation to treat the underlying cause of the hydrops fetalis. Your comprehensive care team at the Midwest Fetal Care Center will explain all treatment options, including surgery, for your baby.

How long will my baby be in the hospital?

Your baby will be discharged from the hospital after the underlying disease that caused the hydrops fetalis has stabilized, the baby has healed from all surgical procedures, and he or she is taking food by mouth without difficulty.

What is my baby’s prognosis?

The prognosis for babies with hydrops fetalis depends on the underlying cause of the condition. Overall, however, the survival rate is low. More than half of all babies with the condition die before birth or soon after delivery. The risk is highest for those who are diagnosed with hydrops fetalis early (less than 24 weeks into pregnancy) and for those who have a structural abnormality, such as a heart defect.

Will my baby require long-term follow-up?

Because of the potential health issues associated with hydrops fetalis, your baby may require long-term follow-up care. At Children’s Minnesota, we have developed a detailed care plan for babies born with hydrops fetalis. Your baby’s plan will be implemented by a comprehensive team of specialists, including a pediatrician (who will coordinate your baby’s overall care), a pediatric cardiologist, a developmental specialist and any other caregivers your baby may require.

Contact us

Need a referral or more information? You or your provider can reach the Midwest Fetal Care Center at 855-693-3825.