Middle cerebral artery blood flow in the fetus and central nervous system complications in the neonate

Abstract

Objective: To evaluate the ability of blood flow (S/D) ratios in the fetal middle cerebral artery (MCA) to predict the occurrence of central nervous system (CNS) complications (bleeding and/orischemia) in the neonate, and compare MCA flow to other tests of fetal well-being.Study design: This was a retrospective, observational, cross-sectional clinical outcome study of high-risk patients,evaluated in the Perinatal Center of the author's institution, who underwent antenatal testing with non-stress test (NST) and Doppler studies (including studies of the fetal umbilical artery and MCA) within1 week of delivery. MCA flow was converted to multiples of the mean, and appropriate parametric and non-parametric statistics were used to compare MCA flow to the presence or absence of CNS complications.Comparisons were also made for the other tests of fetal well-being.Results: CNS complications occurred only in infants who were delivered at less than 37 weeks of gestation (n = 14/131)and the analysis was limited to these 131 patients. Univariant analysis showed that only the NST correlated with CNS complications (OR = 5.46 (1.48-22.16)) and logistic regression confirmed the association.Neither increased diastolic flow in the MCA nor the presence of shunting correlated with CNS complications.Conclusions: This study confirms previous reports that fetal shunting, with decreasedresistance and increased flow in the CNS, is a benign adaptive mechanism for the fetus under stress and not an increased risk for CNS complications. A non-reactive NST, however, is a very late sign of fetalcompromise and is significantly associated with the risk of developing CNS complications.