Definition
- Latin for “edema of the fetus.”
- Refers to an abnormal accumulation of fluid in more than one fetal extravascular compartment.
Incidence
Less than 1% of pregnancies.
Diagnosis
- Hydrops fetalis is a sonographic diagnosis requiring the presence of an abnormal accumulation of fluid in more than one fetal extravascular compartment, including subcutaneous edema, ascites, pericardial effusions, and, pleural effusions. Subcutaneous edema, or placental edema. Polyhydramnios is seen in 50–75% of cases.
- A search for the underlying cause should include:
1 a detailed history (eg, of recent maternal infection)
2 serologic screening (blood type and antibody screen, antibody screen for toxoplasmosis, rubella, cytomegalovirus, herpes [“TORCH titers”])
3 Kleihauer–Betke test (an acid elution test to estimate the total volume of fetal–maternal hemorrhage)
4 ultrasound survey with or without fetal karyotype.
Prognosis
- Depends on gestational age, severity, and etiology.
- Overall perinatal mortality rate exceeds 50%.
Classification
Non-immune fetal hydrops (90%)
- Definition. Hydrops fetalis without an immune etiology.
- Incidence. This is 1 in 2000 live births. Since the introduction of anti-D immunoglobin G (IgG), non-immune hydrops is the most common cause of hydrops fetalis.
- Etiology. The major causes of non-immune hydrops include:
1 idiopathic (no known cause) (50–60%)
2 cardiac abnormalities (20–35%) including congenital dysrhythmias and structural anomalies
3 chromosomal anomalies (15%) such as Turner syndrome
4 hematologic aberrations (10%) such as α-thalassemia, fetal anemia
5 other causes (fetal structural anomalies, infection, twin–twin transfusion syndrome, vascular malformations, placental anomalies, congenital metabolic disorders).
