Sinusoidal fetal heart rate pattern associated with the twin to twin transfusion syndrome.

Sinusoidal fetal heart rate pattern (FHR) is regarded by most authors as signifying a compromised fetus. In most cases, this is secondary to fetal anemia of different causes, usually Rh isoimmunization, more rarely to fetomaternal transfusion, bleeding vasa previa, placental chorioangioma, or traumatic amniocentesis. A case is described which to our knowledge is the first reported of a sinusoidal FHR pattern occurring in the relatively anemic donor twin in a case of the twin to twin transfusion syndrome. The importance of separate antepartum biophysical evaluation of each member of a twin pregnancy is emphasized.