First trimester uterine, placental and yolk sac haemodynamics in pre-eclampsia and preterm labour

We hypothesized that impaired trophoblast invasion leads to umbilicoplacental blood flow disturbances that could be detected by Doppler ultrasonography during the first trimester of the pregnancy.

After successful fresh IVF or ICSI programme, 41 of 47 enrolled subjects were followed up every 1-2 weeks between weeks 6 and 11 of gestation. Ten patients who later developed pre-eclampsia and/or preterm labour formed the study group and the control group consisted of 31 uncomplicated IVF/ICSI pregnancies. Doppler parameters of uterine, spiral, intraplacental, chorionic, umbilical and yolk sac haemodynamics were assessed.

At the week 8, the study group demonstrated higher (P < 0.05) maternal intraplacental resistance indices (RI) than the control group. A week later, yolk sac artery RI and umbilical artery mean velocity (V(mean)) in the study group were lower (P < 0.05) compared to the control group. In late first trimester, increased (P < 0.01) velocities and RI were observed in chorionic arteries of the study group. During early pregnancy, no difference in uterine and spiral artery haemodynamics and in umbilical artery pulsatility index (PI) values was observed between the groups.

Uterine and spiral artery RI and umbilical artery PI are unable to detect placental vascular disturbances during early pregnancy. Elevated intraplacental RI indicates increased maternal intraplacental impedance as early as week 8 of gestation. Decreased yolk sac artery RI and umbilical artery V(mean) in the study group at week 9 of gestation were speculated to indicate hampered transition of blood supply from yolk sac to umbilical circulation, underlining the emphasized role of yolk sac function for the maintenance of pregnancy.