Umbilical lactate as a measure of acidosis and predictor of neonatal risk: a systematic review

Abstract

Background: Umbilical cord lactate is one approach to measuring acidosis and intrapartum hypoxia, knowledge of which may be helpful for clinicians involved in the care of women and newborns. Objective: To synthesise the evidence on accuracy of umbilical cord lactate in measuring acidosis and predicting poor neonatal outcome. Search strategy: Studies published and unpublished between 1990 and 2014 from PubMed/Medline, EMBASE, Cochrane Central Register of Controlled Trials, and clinicaltrials.gov were assessed. Selection criteria: Cross-sectional and randomised studies that assessed fetal acidosis (using lactate as the index test) with or without an assessment of neonatal outcome. Data collection and analysis: Correlations between index and reference test(s) were recorded, as were the raw data to classify the predictive ability of umbilical lactate for neonatal outcomes. Meta-analysis of correlation was performed. We plotted estimates of the studies' observed sensitivities and specificities on Forest plots with 95% confidence intervals (CI). Where possible, we combined data using meta-analysis, applying the hierarchical summary receiver operating characteristics model and a bivariate model. Main results: Twelve studies were included. Umbilical lactate correlated with pH [pooled effect size (ES) −0.650; 95% CI −0.663 to −0.637, P < 0.001], base excess (ES −0.710; 95% CI −0.721 to −0.699, P < 0.001), and Apgar scores at 5 minutes (ES 0.300; 95% 0.193–0.407, P < 0.001). Umbilical lactate had pooled sensitivity and specificity for predicting neonatal neurological outcome including hypoxic ischaemic encephalopathy of 69.7% (95% CI 23.8–94.4%) and 93% (95% CI 86.8–96.3%). Authors' conclusion: Umbilical cord lactate is a clinically applicable, inexpensive and effective way to measure acidosis and is a tool that may be used in the assessment of neonatal outcome. Tweetable abstract: Umbilical cord lactate: a clinically applicable, inexpensive, effective way to measure intrapartum acidosis.