umbilical venous flow assessment
Umbilical venous flow in the physiological situation comprises of a monophasic non-pulsatile flow pattern in the umbilical vein with a mean velocity of 10-15 cm/s. Since a normal umbilical vein supplies a continuous forward flow of oxygenated blood to the fetal heart, the presence of pulsatility implies a pathological state unless in the following situations:
- early in pregnancy: up to ~13 weeks gestation
- the presence of pulsatility may be higher in chromosomally abnormal fetuses even in early pregnancy
- when confounded by other movement variables such as
- fetal breathing movement
- fetal hiccups
Pulsations of the umbilical venous system, especially double pulsations have been associated with increase in the perinatal mortality when associated with the absent and reversed end-diastolic flow velocity in the umbilical artery.
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