Hydrops fetalis is a life-threatening condition characterized by the accumulation of abnormal amounts of fluid in two or more areas of a fetus or newborn’s body, leading to edema (excessive swelling). The fluid may accumulate in the abdominal cavity, around the lungs, around the heart, or in the skin or scalp.
The condition occurs in about one in 2000 births, and nearly half of the babies born with it do not survive (1) (2). The condition can be diagnosed before and after birth, and the survival rate may improve with appropriate parental investigation and therapy (3).
Hydrops fetalis is generally a symptom of underlying conditions (4). Read this post as we tell you about its types, causes, symptoms, diagnosis, risks and complications, treatment options, and prognosis.
Types And Causes Of Hydrops Fetalis
Based on the causes, there are two types of hydrops fetalis.
1. Immune hydrops Fetalis (IHF)
IHF is a rare form of hydrops fetalis that occurs in around 10% of cases (4). The most common cause of immune hydrops is Rh incompatibility between the mother and baby. If the mother is Rh-negative and her baby is Rh-positive, the mother’s immune system attacks the baby’s red blood cells, resulting in anemia. If the baby is unable to overcome the anemia, it might result in heart failure and subsequently lead to the accumulation of large amounts of fluid in the baby’s tissues (5).
IHF is uncommon today because Rh-negative women are generally treated with Rh immunoglobulin (RhoGAM).
2. Non-Immune hydrops (NIHF)
NIHF is a more common type of hydrops and occurs in about 90% of cases. It generally occurs when a genetic disorder, an underlying condition, or a congenital disability impedes the body’s ability to manage fluid. Some underlying causes that can result in non-immune hydrops include (5) (6):
- Heart or lung defects
- Metabolic disorders like Gaucher’s disease
- Infections present during pregnancy
- Severe anemia
- Liver problems
- RBC formation and metabolism-related disorders
- Disorders of the RBC membrane
- Urinary and digestive problems
- Maternal diseases, such as diabetes mellitus and hyperthyroidism
- Vascular malformations and tumors
Symptoms Of Hydrops Fetalis
Hydrops fetalis can pose serious risks both during and after the pregnancy and can affect both the mother and the baby. The symptoms of hydrops fetalis may vary in every child and during pregnancy and after birth.
Some common symptoms of hydrops are (5).
- Thickened placenta
- Increased amniotic fluid
- Enlarged liver, spleen, or heart
- Ascites — fluid build-up in the baby’s abdomen
- Severe swelling in the baby’s body
- Difficulty breathing
- Enlarged spleen and liver
- Pale color of skin
- Chances of heart failure
- Severely low blood sugar levels
Risks And Complications Of Hydrops Fetalis
- Intrauterine fetal demise
- Preterm delivery
- Perinatal death
- Early death of the neonate
- Kernicterus — a rare kind of preventable brain damage
- Developmental delays
- Appendiceal rupture
- Cystic hygroma
- Intestinal obstruction
Diagnosis Of Hydrops Fetalis
A routine ultrasound during pregnancy can help detect fluid accumulation in one or more areas of the baby’s body. It also helps the doctor see the blood flow in the baby’s blood vessels.
2. Fetal blood sampling
If hydrops is suspected in a routine prenatal ultrasound, a fetal blood sampling may be done by obtaining fetal blood from the umbilical cord or blood vessels.
Like fetal blood sampling, amniotic fluid is collected from the amniotic sac to detect any genetic or chromosomal abnormalities.
Other additional tests that can help the doctor determine the cause of hydrops fetalis in a baby include
- MRI to visualize fetal anatomy and physiology and identify any birth defects.
- Fetal echocardiogram to evaluate the baby’s heart
Treatment For Hydrops Fetalis
The treatment for hydrops fetalis depends on the cause and can begin immediately after detection during pregnancy.
Treatment during pregnancy
- Medications to cause early labor and delivery.
- Cesarean delivery to reduce the risks if the condition worsens.
- An intrauterine fetal blood transfusion.
Treatment in the newborn baby
- Direct blood transfusion in the case of immune hydrops.
- Removal of the accumulated fluid using a needle.
- Medications to control fluid build-up in the kidney and heart.
- Ventilator support to breathe.
- Medications to treat fetal arrhythmia.
- Surgery to treat lung or heart defects.
Prognosis Of Hydrops Fetalis
The prognosis for babies born with hydrops depends upon many factors, including the (6)
- Underlying cause of the
- Gestational age of the fetus at the time of infection
- Build-up of fluids or edema in the
- Interventions performed in the intrauterine (within the uterus) period.
Generally, the earlier in the pregnancy the condition occurs, the greater the risk to the fetus. Babies with thoracic causes and bronchopulmonary defects have a good prognosis than those with genetic or chromosomal abnormalities. Also, babies who have had fetal interventions and in whom the condition was controlled without preterm birth have improved chances of survival.
The prognosis depends upon the damage done by the fluid on the baby’s organs. Babies with hydrops who have structural defects or no identified cause of the condition are at higher risk for morbidity and mortality.
Hydrops increases the risk of pregnancy significantly. Babies born with this condition show varied symptoms, and it is crucial to determine the underlying cause. The condition can be diagnosed using routine ultrasounds, fetal blood sampling, and amniocentesis.
2. Hydrops Fetalis; Boston Children’s Hospital
3. K Sohan et al.; Analysis of outcome in hydrops fetalis in relation to gestational age at diagnosis, cause and treatment; Acta Obstetricia et Gynecologica Scandinavica (2001).
4. Hydrops fetalis; Radiopaedia
5. Hydrops Fetalis; Stanford Children’s Health
6. Rachana Vanaparthy and Heba Mahdy; Hydrops Fetalis; StatPearls (2021).
7. Hydrops Fetalis; Stanford Children’s Health
8. Hydrops fetalis; MedlinePlus
9. Hydrops fetalis/erythroblastosis fetalis; Children’s Wisconsin
10. Non-Immune Hydrops; Texas Children’s Hospital