Sonographic evaluation of hydrops fetalis.

Sonographic criteria were developed to aid in determining the cause of hydrops fetalis in 26 consecutive cases diagnosed antenatally. This enabled us to predict whether the hydrops was due to anemia-related causes (isoimmunization, fetomaternal hemorrhage, alpha-thalassemia) or non-anemia-related causes. Fetuses without anemia as the cause of hydrops most often exhibited pleural effusions (87%) or marked edema (62.5%). A combination of pleural effusions and marked edema was evident in fetuses without anemia 56.3% of the time. Those with anemia as the cause of hydrops were significantly less likely to exhibit pleural effusions (20%), marked edema (10%), or pleural effusions and marked edema (10%). A thickened placenta occurred significantly more frequently (80 versus 37%) in anemia-associated hydrops. With the use of cordocentesis and intravascular in utero transfusion, the early recognition and treatment of hydrops fetalis due to anemia should lead to improved outcome in fetuses so affected.