Hydrops fetalis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at August 30, 2016
StartDiseasesHydrops fetalis

Hydrops fetalis, also known as fetal hydrops or simply hydrops, is a rare but life-threatening condition that affects fetuses and newborns. It affects approximately 1 in 1,500 to 1 in 4,000 children born. This condition causes fluid to build up in multiple areas of the body, indicating a more serious underlying condition. 


Definition & Facts 

Hydrops fetalis is a condition that indicates other, more serious conditions within the fetus or newborn. These underlying conditions manifest themselves as severe edema or swelling.

Hydrops is most simply defined as the unusual pooling of fluid around organs in at least two places. Fluid commonly forms in the spaces around the abdomen, lungs, and/or heart.

There are two forms of hydrops: 1) immune hydrops and 2) non-immune hydrops. The vast majority, 75 to 90 percent, of hydrops cases are of the non-immune variety. Non-immune hydrops is also responsible for 60 to 90 percent of hydrops deaths.

Symptoms & Complaints

Symptoms include enlarged organs such as the heart (cardiomegaly), liver (hepatomegaly), and spleen (splenomegaly). Other symptoms of this condition are dependent on whether the condition occurs in a fetus or a newborn. Fetal symptoms include:

Neonatal or newborn symptoms include: 

The most prominent symptom of hydrops is fluid accumulation. This buildup of fluid occurs when too much fluid escapes the bloodstream.


There are various diseases that cause hydrops. Rh disease is known to cause immune hydrops because an Rh-negative mother’s antibodies attack the incompatible red blood cells of her Rh-positive baby. The red blood cells carry oxygen, and consequently, the baby becomes anemic.

The baby’s newly formed organs cannot withstand this type of attack, or the lack of oxygen. Ultimately, the baby’s overworked organs begin to enlarge, and the baby starts to experience heart failure. This leads to fluid accumulation throughout the body and systemic swelling.

Non-immune hydrops is not caused by any one disease. Any other disease that disrupts the body’s ability to properly manage its fluids can cause non-immune hydrops. This form of the condition is often attributed to congenital heart defects or lung diseases, liver disease, chromosomal abnormalities, genetic disorders, metabolic disorders, and fetal bleeding.

The mother can pass certain bacterial infection and viral infections to the baby during pregnancy, causing hydrops fetalis. Such infections include parvovirus infection, cytomegalovirus (CMV) infection, and syphilis. Some diseases also impair the production of red blood cells or cause the blood cells to be more susceptible to destruction.

Diagnosis & Tests 

A physician will typically diagnose hydrops in an unborn fetus via medical ultrasound. During the ultrasound, the doctor will look for excess fluid in two or more areas in the body. If the fluid is detected, the doctor may diagnose this condition. Failure to detect fluid in more than one area of the baby’s body does not lead to a diagnosis.

If a doctor makes a preliminary diagnosis of hydrops, he or she will perform a blood test to determine whether the baby has immune or non-immune hydrops. This distinction is made by means of a blood test. This blood test looks for antibodies in the mother’s blood that indicate blood incompatibility. 

The doctor will also test for any underlying diseases or disorders that caused the hydrops. The physician may perform an echocardiogram, which is an ultrasound of the heart. The echocardiogram can discover irregular heart rhythms or physical deformities in the heart.

Additional procedures will test for congenital and hereditary conditions. After diagnosis and additional testing, the doctor will likely refer the mother and child to one or more specialists. Examples include:

  • A geneticist who can identify any genetic condition(s) that may cause hydrops. 
  • A perinatologist who specializes in high-risk pregnancies. The specialist will monitor the mother’s as well as the baby’s condition throughout the pregnancy.
  • A neonatologist who can give specialized care to the baby after he or she is born.

Treatment & Therapy

Treatment of this condition is highly variable and depends on the cause of the hydrops fetalis. It also depends on the level of risk associated with the treatment weighed against the potential benefit(s) to the baby. When the doctor cannot determine the precise cause of hydrops (it is idiopathic), the goal of treatment is to provide comfort care.

Otherwise, treatment options include: induced labor or caesarean section to deliver the baby early or a blood transfusion for the baby before or after birth. Blood transfusions are common when the condition that causes hydrops is low blood counts. When the baby is not yet born, the physician will insert a needle into the umbilical cord to transfer blood. This procedure will be repeated until the blood levels reach an initially acceptable level, then again at regular interval intervals until the mother reaches around 34 or 35 weeks in her pregnancy.

The physician may also use a needle to extract fluid from all areas where fluid has accumulated. In some scenarios, the physician may require a waiting period to see if the child’s body will naturally reabsorb the excess fluid. Additional courses of treatment may consist of medication for the mother or child, use of a breathing machine, or oxygen supplementation for the baby. 

Prevention & Prophylaxis

Immune hydrops fetalis is preventable in many cases. Since the 1960s, there has been a dramatic decrease in immune hydrops. This is due to the development of an injectable drug, Rho(D) immune globulin which is available to pregnant women. The drug prevents women at risk for Rh incompatibility from producing the antibodies that would otherwise attack her baby’s red blood cells.

There are measures to prevent further complications of non-immune hydrops fetalis by means of the prenatal treatment options highlighted above.