Sinusoidal fetal heart rate pattern after intrauterine transfusion.

Two pregnancies complicated by severe Rh-isoimmunization and the development of sinusoidal fetal heart rate patterns immediately after intrauterine transfusions are presented. An intermittent sinusoidal pattern resolved, in one fetus, with sonographic evidence of delayed but complete absorption of transfused red blood cells. In contrast, the second fetus exhibited a continuous sinusoidal pattern coincident with cardiac decompensation detected by echocardiography, severe anemia, and failure to absorb transfused red blood cells. Possible pathophysiologic mechanisms for the development of sinusoidal patterns after fetal transfusions are discussed. It is concluded that a sinusoidal fetal heart rate pattern may occur after fetal transfusion and that the subsequent course of this pattern provides meaningful information about fetal condition as well as the success of intrauterine transfusion.