Hydrops fetalis is a fatal condition where the accumulation of unusual amounts of fluids in different parts of the body of a fetus or newborn can lead to edema (excessive swelling). The accumulation can occur in the skin or the scalp. It may also occur around the lungs and heart, and abdominal cavity.
It occurs in 1 in 2000 births, and nearly half of the babies with the condition may not survive (1) (2). Hydrops fetalis is usually a manifestation of an underlying health condition and is diagnosed before or after birth. The survival rate may improve with the proper prenatal investigation and subsequent therapy after birth (3) (4).
Read on to know more about hydrops fetalis, including its causes, symptoms, complications, and treatments.
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 fetalis (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.
- 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 better 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.
Frequently Asked Questions
1. Is hydrops fetalis hereditary?
Yes. Hydrops fetalis, in particular, nonimmune hydrops fetalis, can be caused by hereditary disorders such as Turner syndrome, skeletal dysplasia, inborn metabolic errors, chromosomal abnormality, and autosomal recessive and autosomal dominant conditions (11) (12).
2. When is hydrops fetalis detected in pregnancy?
During pregnancy, hydrops fetalis is usually detected during a routine prenatal ultrasound exam. However, your obstetrician may suggest specific tests, such as an ultrasound exam, fetal blood sampling, and amniocentesis, if you have a known risk due to maternal red cell antibodies or they notice signs such as decreased fetal movements (13).
This rare and serious condition of hydrops fetalis can increase pregnancy risk factors for complications and pose a threat to the baby’s health. However, timely diagnosis and treatment can help manage the condition. Given hydrops fetalis can be recognized with its significant prenatal and after-birth symptoms through monitoring, ultrasound, and other tests, it is important to be aware of the signs and keep up with your ob/gyn visits. If you or your baby displays any symptoms, consult your doctor immediately to prevent further complications.
- Hydrops fetalis can be immune hydrops fetalis due to Rh incompatibility and non-immune hydrops fetalis caused by genetic reasons or underlying conditions.
- Anemia, jaundice, spleen and liver enlargement, pale skin, and breathing difficulties are common symptoms in hydrops fetalis.
- Blood transfusion, fluid removal, and medications to control excess fluid accumulation are recommended to manage hydrops fetalis.
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
11. L Van Maldergem et al.; Genetic causes of hydrops fetalis; Paediatrics (1992).
12. Dawn M.Hannah et al.; Nonimmune hydrops fetalis due to autosomal recessive hereditary spherocytosis; Case Reports in Women’s Health (2017).
13. What is hydrops fetalis? MIDWEST FETAL CARE CENTER