NEUROPATHOLOGY OF THE NEAR-TERM AND MIDGESTATION OVINE FETAL BRAIN AFTER SUSTAINED IN-UTERO HYPOXEMIA

OBJECTIVE: The neuropathologic mechanisms of the ovine fetal brain in response to several hours of sustained hypoxemia with variable degrees of metabolic acidemia was investigated in both the preterm and near-t erm ovine fetus. STUDY DESIGN: Three groups of fetuses were studied in each of the near-term and midgestation groups: a hypoxic group, a con trol group, and an uninstrumented control group. Histopathologic studi es were performed after a 40-hour recovery period after experimentatio n. RESULTS: Pathologic findings consisted of predominately white matte r damage with some adjacent cortical necrosis but no selective neurona l injury. In the near-term group the hypoxia group fetuses demonstrate d significantly higher white matter injury scores than did control gro up fetuses (p < 0.05). Periventricular white matter injury was the pre dominant pattern seen in the midgestation group. CONCLUSIONS: In spite of normalization of biophysical and biochemical parameters after hypo xemia both midgestation and near-term fetuses sustained pathologic cha nges. Presence or extent of injury did not correlate with the degree o f hypoxemia or metabolic acidosis achieved.