Recent advances in the Doppler study of early fetomaternal circulation.

Abstract

Transvaginal color Doppler has enabled precise investigation of feto-maternal circulation in early pregnancy. Decrease of peripheral impedance, as well as increase of blood flow velocity was found in all segments of the uteroplacental circulation with gestational age. The same finding was observed in umbilical artery, fetal aorta and intracranial blood vessels. A significant decrease of vascular impedance in cerebral blood vessels exists earlier than in fetal aorta or umbilical artery which could be explained by the establishment of cerebral autoregulation mechanisms which ensure adequate oxygen and glucose supply to embryonic brain. There was no significant difference for RI values of luteal blood flow from the 6th to the 12th gestational week. No difference was found between RI values of luteal blood flow in normal and ectopic pregnancy. In threatened, incomplete and missed abortions RI of luteal blood flow was significantly higher in comparison with normal pregnancy. It seems that in the group of patients with threatened abortion, follow up of the luteal flow might give some prognostic value. No difference in peripheral impedance and blood flow velocity of the uteroplacental blood vessels was found between women with normal pregnancies and women with threatened abortions and normal pregnancy outcome. There was no significant difference in terms of RI and PSV in uteroplacental blood vessels between women with threatened abortion and normal pregnancy outcome and women with threatened abortion whose pregnancy terminated with complete abortion and blighted ovum. In 46% of 21 women with visible retrochorionic hematoma RI in spiral arteries was higher and PSV was lower on the side of the hematoma. These values could be explained by compression of the wall of the spiral arteries caused by hematoma. In missed abortion the mean RI value of the uterine artery was lower than the mean value in normal pregnancy, but was not in spiral arteries. Some authors reported RI values in cases of missed abortions around and above the cutoff point value of 0.63. In blighted ovum RI in uterine and spiral arteries was lower in comparison to normal pregnancy, but in the other studies this was not the case. Increased blood flow in radial arteries in patients with pregnancy associated with uterine myomata could be explained by higher levels of estriol hormone metabolized in the placenta. Transvaginal color Doppler could be helpful in diagnosis and differentiation of the different forms of a gestational trophoblastic disease. It seems that this technique is a good substitute for pelvic angiography.(ABSTRACT TRUNCATED AT 400 WORDS)