Umbilical cord blood lactate: a valuable tool in the assessment of fetal metabolic acidosis.

Objective: The aim of the present study was (1) to evaluate the relationship between umbilical cord arterial blood lactate and pH, standard base excess (SBE), and actual base excess (ABE) at delivery and (2) to suggest a cut-off level of umbilical cord arterial blood lactate in predicting fetal asphyxia using ROC-curves, where an ABE value less than -12 was used as "gold standard" for significant intrapartum asphyxia.

Study Design: This is a descriptive study of umbilical cord arterial blood samples from 2554 singleton deliveries. The deliveries took place at the Department of Obstetrics and Gynaecology, Hvidovre University Hospital, Copenhagen, Denmark where umbilical cord blood sampling and blood gas analysis is part of the routine assessment of all newborns.

Results: We found significant correlations between lactate and pH (r=-0.73), lactate and SBE (r=-0.76), and lactate and ABE (r=-0.83). ROC-curves suggested a lactate cut-off level of 8mmol/l for indicating intrapartum asphyxia.

Conclusion: Lactate in arterial umbilical cord blood might be a more direct and accordingly more correct indicator of fetal asphyxia at delivery than pH and SBE (or ABE). Its potential as a predictor of neonatal outcome needs to be evaluated in future studies.