Which component of umbilical cord blood is most indicative of neurologic injury due to an acute intrapartum event?

In assessing umbilical cord blood for indications of neurologic injury due to an acute intrapartum event, base deficit levels are particularly relevant. A significant base deficit reflects an accumulation of metabolic acids in the blood and suggests that the fetus has experienced a degree of metabolic acidosis, which can be a consequence of hypoxia or reduced placental perfusion during labor.

When the fetus is exposed to an acute event that compromises oxygen delivery, such as uterine contractions that reduce blood flow, the resulting decrease in oxygen can lead to increased anaerobic metabolism. This process generates lactic acid, thereby lowering the base level in circulation. A higher base deficit indicates a more severe disturbance, potentially correlating with the risk of neurologic injury or long-term neurodevelopmental complications.

While lactate levels do provide useful information regarding metabolic status, the base deficit is a more direct measure of the overall acid-base balance and metabolic response to acute stressors during the intrapartum period. Elevated bilirubin levels are typically related to hemolysis or jaundice rather than immediate neurologic injury, and a normal pH typically indicates that there is no significant acidosis present, which would not suggest an acute injury.