Nonimmune hydrops fetalis (NIHF), also called nonimmune fetal hydrops, is the pathologic accumulation of fluid in the fetus causing generalized edema and fluid collections in body cavities (pericardial effusion, pleural effusion, ascites) in the absence of Rh incompatibility or other immune-mediated hemolysis. Causes are diverse and include cardiac defects, arrhythmias, infections (TORCH), chromosomal abnormalities, anemia, and placental problems. On prenatal ultrasound, hydrops is documented by measurement of skin thickness (>6 mm suggests hydrops), presence of effusions, and other edema findings. The prognosis of NIHF depends on the underlying cause; while some causes respond to prenatal treatment, many carry a poor prognosis. Thorough evaluation including fetal echocardiography and possibly fetal magnetic resonance imaging is warranted to identify a treatable cause.
Sonography Term