Absence of neuronal damage after umbilical cord occlusion of 10, 15, and 20 minutes in midgestation fetal sheep.

Abstract

Our purpose was to determine whether neuronal damage results after total umbilical cord occlusion of increasing duration in midgestation fetal sheep. We performed total umbilical cord occlusion during 10 (n = 11), 15 (n = 8), or 20 (n = 4) minutes in chronically instrumented midgestation fetal sheep. Nine fetuses served as sham controls. During the experiment fetal blood pressure (mean arterial pressure) and heart rate were continuously recorded. Fetal blood gas analyses were performed at regular intervals before, during, and after the occlusion. Three days after the occlusion neuronal damage was evaluated histologically in three regions of the fetal brain. Total umbilical cord occlusion resulted in hypotension, bradycardia, severe mixed acidemia, hypoxia, and hypercapnia. All fetuses survived the occlusion. No neuronal damage nor macroscopic intraventricular or germinal matrix hemorrhages were observed in either group. Prolonging the duration of total umbilical cord occlusion in midgestation fetal sheep resulted in a progressive increase in the severity of asphyxia, not in neuronal damage.