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[Doppler ultrasound in obstetrics--contribution to understanding reverse flow in the umbilical artery].

"Reverse Flow" as a Doppler sonographic finding indicates the appearance of retrograde blood flow in the diastolic part of the cardiac cycle. It has so far not been observed in uncomplicated pregnancies and seems to be an indicator of severe deterioration of the foetal condition. Several pathophysiological hypotheses are discussed in this paper on the basis of own results and the findings of other investigators.