Hydrops fetalis, or hydrops, is a condition in which fluid accumulates in different parts of the fetal body. There are two types: immune and non-immune. The immune type is caused by destruction of fetal red blood cells by the mother’s immune system. The non-immune type is more common and has a variety of causes, including viral infections, heart or lung abnormalities, and genetic conditions.
Non-immune hydrops occurs in 1 in 1500 to 1 in 4000 births. Although an exact rate is unknown, immune hydrops is rare.
If suspected, a detailed ultrasound will be performed to look for other abnormalities. Fetal echocardiography will be recommended to further evaluate fetal heart structure and function. As infections, other anomalies, and genetic abnormalities are commonly associated with this finding, genetic counseling and diagnostic testing are recommended. In cases where severe anemia is suspected as a cause, cordocentesis may be recommended. Prenatal care will be managed by a Maternal-Fetal Medicine specialist, an obstetrician with special training and expertise in high-risk pregnancies. The pregnancy will be closely monitored, as will the mother who is at risk for specific health complications. Prenatal consultations with neonatology and other pediatric subspecialists may be recommended to discuss the condition, its prognosis, and management after birth.
Hydrops is a serious condition and the prognosis depends on the underlying cause. Overall, though, the outlook is poor.