Ductus venosus blood velocity and the umbilical circulation in the seriously growth-retarded fetus.

Abstract

Based on the assumption that the ductus venosus is regulator of oxygenated blood in the fetus, the present study investigated the blood flow velocity of the ductus venosus in relation to the umbilical circulation in the that seriously growth-retarded fetus. The study group of 38 fetuses (gestational week 17-39) had no chromosomal aberrations or structural malformations and had an ultrasonographic biometry of < 2.5th centile and birth weight of <or= 2.5th centile. Of the 38 fetuses seven died in utero and four died postnatally. The ultrasonographic examination included pulsed Doppler measurement of the umbilical artery pulsatility index (PI), the umbilical vein dimension and blood flow velocity, and the peak and maximum blood flow velocities of the ductus venosus. The majority of fetuses had a raised PI in the umbilical artery (26/38) and reduced blood flow in the umbilical vein (25/33). Despite such changes in the umbilical circulation, a normal peak velocity in the ductus venosus was maintained in all fetuses. During the atrial contraction, however, 13 fetuses had reduced or reversed blood velocity in the ductus venosus. Reduced ductus venosus velocity during atrial contraction seemed to be a serious finding linked to raised PI and absent or reversed end-diastolic flow in the umbilical artery, and umbilical vein pulsation. The results support the assumption that the blood flow of the ductus venosus is a preferential bloodstream in the human fetus that is maintained within normal ranges as long as possible during placental hemodynamic compromise.