[Sinusoidal fetal heart rhythm (author's transl)].
The authors describe 6 cases of pregnancy, four of the patients presenting fetomaternal Rhesus incompatibility, and two showing no abnormality. Fetal heart rhythm (FHR) recordings in all patients demonstrated the presence of a sinusoidal rhythm, either alone or associated with deceleration. The physiopathology of the rhythm, according to a very critical analysis of reports in the published literature (very severe fetal anemia, hypoxia), was not typical in three of the cases. The authors conclude that the observation of this sinusoidal rhythm for a period of up to 60 min, but not repeated, does not constitute a danger for the fetus. If the period is longer, however, or if there is a fetomaternal pathological condition, decelerations, or reduced amplitude of FHR oscillations, there is a very severe risk to the fetus and the need for urgent delivery has to be seriously considered.