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/or ischemia) 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) within 1 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 decreased resistance 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 fetal compromise and is significantly associated with the risk of developing CNS complications.