Lactate Pro devices have a significant difference, but when used in clinical practice on cord blood after delivery, this is unlikely to be meaningful. In intrapartum fetal surveillance, a systematic overestimation might lead to unnecessary intervention. It is possible to retrospectively predict the likely level of lactate at birth in delayed cord samples.

Objective: Fetal scalp lactate has largely replaced pH analysis to assess intrapartum hypoxia. Many obstetrics units use hand-held lactate meters to measure umbilical blood because of its affordability and ease of use. We sought to investigate the agreement of Lactate Pro TM with a reference method blood gas analyser and to determine its usefulness with a recommended cutoff value of 4.8 mmol/L. Methods: Prospective study carried out at a tertiary institution where 237 arterial and 233 venous samples from umbilical cords of 16 elective caesarean and 285 emergency deliveries were measured using Lactate Pro TM and ABL735 Sesries Acid-Base analyser. Limits of agreement were analysed using Bland-Altman plots. Results: Lactate Pro TM differentiated fewer deliveries as "high risk" (≥4.8 mmol/L) and more as "low risk" (<2.2 mmol/L). Limits of agreement for lactate values (as measured by Lactate Pro TM) were-1.46-0.97 mmol/L for arterial lactate levels <4.8 mmol/L and-3.21-0.88 mmol/L for arterial lactate levels ≥ 4.8 mmol/L. Conclusion: There was a poorer agreement between the two devices at higher lactate values. Lactate Pro TM underestimates by up to 3.2 mmol/L; a 4.8 mmol/L reading may actually signify a lactate level of 8.0 mmol/L, indicating severe metabolic acidosis. We caution the use of this device in assessing fetal lactate levels.