Scalp blood lactate: a new test strip method for monitoring fetal wellbeing in labour

Abstract

Objective To determine fetal scalp blood lactate with a new test strip method in parturients with normal and abnormal cardiotocograms during labour and to describe the relation to maternal lactate, fetal scalp blood pH, cord artery lactate and acid‐base balance. Setting Labour wards at the University Hospitals of Huddinge and Lund and at the County Hospital of Östersund, Sweden. Materials and method Fetal scalp blood was sampled for lactate (n= 269) and pH (n= 285) determination in 177 parturients with abnormal intrapartum CTG. Lactate and pH were also analysed in a group of 64 women with normal pregnancies and with a reactive fetal heart rate tracing prior to sampling of fetal scalp blood. At fetal blood sampling lactate was also determined in maternal capillary blood, while at birth lactate and acid‐base balance in cord artery blood was performed in almost all cases. Main outcome measurements Medians and percentiles (lactate and acid‐base balance). Correlation between fetal scalp blood lactate (dependent) and scalp blood pH, cord artery blood lactate and acid‐base parameters and labour time prior to fetal blood sampling. Results In the group with abnormal cardiotocograms, fetal scalp and umbilical artery blood lactate and acid‐base parameters differed significantly from the same parameters in the normal group. The fetal‐maternal lactate gradient changed from negative in the normal group to positive in the fetal distress group. Multiple regression analysis, with scalp lactate as the dependent parameter, revealed a significant correlation with fetal scalp blood pH (P < 0.001) and umbilical artery lactate (P < 0.01). Conclusions Intrapartum scalp blood lactate was significantly correlated with pH and cord artery lactate. The results indicate that increased lactate levels in fetal blood sampling describes fetal lactacidosis. The new disposable test strip requiring only 5 μl of blood for lactate determination may be better than traditional methods for monitoring fetal wellbeing in labour.

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

“…Furthermore, the value of scalp lactate has been found to be identical to scalp pH in the prediction of Apgar scores [7] . In a prospective randomized trial, Westgren et al [11] showed that scalp lactate sampling was more easily feasible than scalp pH, especially with the advent of cheap handheld lactate meters [7,8] .…”

“…There is a rise in lactate concentration in cases of fetal metabolic acidosis, due to hypoxia and anaerobic metabolism [6] . Indeed, strong correlations exist between lactate concentration, BD and pH in the umbilical cord blood [7][8][9] , and between scalp lactate and umbilical cord lactate [10] . Furthermore, the value of scalp lactate has been found to be identical to scalp pH in the prediction of Apgar scores [7] .…”

“…Indeed, strong correlations exist between lactate concentration, BD and pH in the umbilical cord blood [7][8][9] , and between scalp lactate and umbilical cord lactate [10] . Furthermore, the value of scalp lactate has been found to be identical to scalp pH in the prediction of Apgar scores [7] . In a prospective randomized trial, Westgren et al [11] showed that scalp lactate sampling was more easily feasible than scalp pH, especially with the advent of cheap handheld lactate meters [7,8] .…”

FIGO consensus guidelines on intrapartum fetal monitoring: Adjunctive technologies

“…Studies in fetal monkeys showed a good correlation of acid-base parameters between scalp and carotid blood [6], and human data have shown similar correlations between pH and lactate values obtained in scalp blood and those recorded shortly after birth in the umbilical artery and vein [7][8][9][10][11]. However, correlation of these values with newborn outcome depends on the time interval between scalp sampling and birth [12].…”

“Every case of asphyxia can be used as a learning example”. Conclusions from an analysis of substandard obstetrical care

“…Furthermore, in cases of acidemia, it is maintained that far more time than foreseen is spent from decision to perform a FBS to when the infant is delivered [2,9] . The introduction of lactate analysis in scalp blood has, however, simplifi ed the method, since only 5 µ L of blood is required for lactate determination [64] . Interpretation value for normal lactate is ( < 4.2 mmol/L), pre-acidocis (4.2 -4.8 mmol/L) and acidosis ( > 4.8 mmol/L) [62,84] .…”