DUCTUS VENOSUS BLOOD VELOCITY AND THE UMBILICAL CIRCULATION IN THE SERIOUSLY GROWTH-RETARDED FETUS

Based on the assumption that the ductus venosus is a regulator of oxyg enated blood in the fetus, the present study investigated the blood fl ow velocity of the ductus venosus in relation to the umbilical circula tion in the seriously growth-retarded fetus. The study group of 38 fet uses (gestational week 17-39) had no chromosomal aberrations or struct ural malformations and had an ultrasonographic biometry of < 2.5th cen tile and birth weight of less-than-or-equal-to 2.5th centile. Of the 3 8 fetuses seven died in utero and four died postnatally. The ultrasono graphic examination included pulsed Doppler measurement of the umbilic al artery pulsatility index (PI), the umbilical vein dimension and blo od flow velocity, and the peak and maximum blood flow velocities of th e ductus venosus. The majority of fetuses had a raised PI in the umbil ical artery (26/38) and reduced bloodflow in the umbilical vein (25/33 ). Despite such changes in the umbilical circulation, a normal peak ve locity 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 durin g atrial contraction seemed to be a serious finding linked to raised P I and absent or reversed end-diastolic flow in the umbilical artery, a nd umbilical vein pulsation. The results support the assumption that t he blood flow of the ductus venosus is a preferential bloodstream in t he human fetus that is maintained within normal ranges as long as poss ible during placental hemodynamic compromise.