Umbilical Cord Venous Lactate for Predicting Arterial Lactic Acidemia and Neonatal Morbidity at Term

OBJECTIVE: To estimate the utility of umbilical venous lactate, more readily available than umbilical cord arterial lactate, for predicting arterial lactic acidemia and neonatal outcomes at term. METHODS: This was a prospective cohort study of consecutive, nonanomalous, singleton, term births after labor in a large academic medical center (2009-2014). Umbilical arterial and venous lactate were measured immediately after delivery, before knowledge of neonatal outcomes. The outcome measures were arterial lactic acidemia (greater than 3.9 mmol/L) and a composite neonatal outcome consisting of neonatal death and any of a number of neonatal morbidities including intubation, mechanical ventilation, meconium aspiration syndrome, hypoxic-ischemic encephalopathy, and therapeutic hypothermia. Predictive ability of venous lactate was estimated using the area under the receiver operating characteristic curve. RESULTS: Among 7,741 births, venous lactate was strongly predictive of arterial lactic acidemia (area under the curve 0.958). The "optimal" cut point of venous lactate for predicting both arterial lactic acidemia and the composite neonatal outcome was 3.4 mmol/L. This predicted arterial lactic acidemia with sensitivity of 87.0% and specificity of 91.3%. Positive and negative predictive values were 79.9% and 94.7%, respectively. The composite neonatal outcome occurred in 104 neonates (1.3%). Compared with arterial lactate, venous lactate predicted the composite neonatal outcome with comparable sensitivity (75.0% compared with 74.0%, P>.99) but slightly lower specificity (69.7% compared with 72.2%, P<.01). CONCLUSION: Umbilical venous lactate strongly predicts arterial lactic acidemia and is comparable with arterial lactate for predicting neonatal morbidity at term. It could be used as a measure of neonatal morbidity when arterial blood is not available.