Daily Doppler assessment of the fetal hemodynamic response to chronic hypoxia: a five-case report

Objective To determine whether long-term fetal brain vasodilatation and hyp erperfusion (duration up to 21 days) with loss of cerebral flow velocity va riability is associated with poor fetal outcome and brain damage. Study design The fetal flow redistribution was assessed by using the cerebr al/umbilical resistance ratio (VU) in five growth-restricted fetuses, usual ly every day for 13-21 days. The evolution of the fetal hemodynamics was in terpreted according to the fetal clinical, anatomical and histological find ings. Results As the C/U ratio was always lower than unity during this period of observation, the fetuses were considered to be in a chronic hypoxic state. All five fetuses had a poor outcome, including death at delivery (n = 2), n eonatal intensive assistance (n = 3) followed by death for two of them. The pO(2) was reduced in the two fetuses who survived for some hours and some days. The fetal deterioration was characterized by the progressive developm ent of oligohydramnios; the disappearance of the cerebral flow velocity, 4- 10 days before delivery in all fetuses; the occurrence of fetal heart rate decelerations in four of them; and the increase of cerebral vascular resist ance for two of them. The anatomical study of the brain in two of them show ed a meningeal and periventricular congestion. The histology revealed patho logical gliosis and a marked vasodilatation of both anterior and middle cer ebral arteries. Conclusion The decrease in the C/U ratio (mean 30-40%) over 11-21 days, whi ch corresponded to sustained hypoxia with increased brain perfusion, and th e loss of cerebral flow variability were associated in all cases with sever e growth restriction and fetal death (four cases) or very poor fetal outcom e (one case). The loss of variability of the cerebral resistance index was probably related to a loss of cerebral flow regulation, or the deterioratio n of brain tissue. Such a pattern may be considered as a predictor of poor fetal outcome, as it occurred 4-10 days before delivery and 3-7 days before fetal heart rate abnormality or increased cerebral resistance. This hypoth esis may have to be confirmed in a larger number of pathological pregnancie s.