Fetal Scalp Lactate Microsampling for Non-Reassuring Fetal Status during Labor: A Prospective Observational Study

<i>Objective:</i> The aim was to study the predictive value and feasibility of fetal scalp lactate microsampling in the management of non-reassuring fetal status during labor. <i>Methods:</i> A prospective observational study was conducted on cord blood gas samplings from 7,617 singleton and cephalic deliveries at ≧37 weeks of gestation. In this population, 450 fetal scalp blood samples (FBS) were performed for abnormal fetal heart rate (FHR) patterns. Microvolume scalp lactate measurements were compared to scalp pH, neonatal cord blood gas parameters (pH, lactate, base deficit) and the Apgar score. <i>Results:</i> Scalp lactate correlated significantly with scalp pH (r = –0.56, p = 0.001), umbilical artery pH (r = –0.39, p = 0.03), umbilical artery lactate (r = 0.48, p = 0.01) and umbilical artery base deficit (r = 0.51, p = 0.01), but not with Apgar scores. Using receiver operating characteristic curves, a scalp lactate cutoff value of 5 mmol/l was the most predictive for neonatal acidosis. Sampling failure with scalp lactate was inferior to scalp pH (1.3 vs. 14%, p < 0.001). <i>Conclusion:</i> Lactate microsampling in fetal scalp blood was found to be an attractive alternative to pH analysis and a useful 2nd-line tool for monitoring fetal asphyxia during labor.