[Interest of lactate micro-dosage in scalp and umbilical cord in cases of abnormal fetal heart rate during labor. Prospective study on 162 patients].

Objective: To compare the interest of lactate microanalysis with pH measurement (Gold Standard procedure) in cord blood and fetal scalp blood samples for the assessment of abnormal fetal heart rate (FHR) during labour.
Study Design: A prospective observational study conducted from July 1st 2007 till March 31st 2008 on 162 patients with abnormal FHR during labour.
Results: Sampling failure for scalp lactate was less than 1 % compared to a failure of 10.5 % for scalp pH (P<0.001). There was a good correlation between pH and lactates in fetal scalp blood samples and in cord blood samples, between lactate in the last fetal scalp sample and in cord blood. When there was umbilical acidosis (pH≤7.15 or lactate≥5mmol/L), Apgar score at 5 minutes was significantly lower than when there was no acidosis (4.66±3.59 versus 8.35±2.73 for pH ; 6.6±3.77 versus 8.45±2.58 for lactate). The specificity of the lactate in the umbilical cord artery (≥5 mmol/laws) was 76.4 % for predicting an Apgar score at 5 minutes less than 7 ; 79.7 % for predicting the need for immediate neonatal care ; 77.3 % for predicting an hospital stay in neonatal unit. These figures were generally worse but close to those found for a threshold value of umbilical artery pH≤7.15.
Conclusion: The values of lactate in cord blood and fetal scalp blood samples were comparable to pH values (Gold standard procedure). This method is easy to perform and is an attractive alternative to pH for monitoring fetal asphyxia. It is our opinion that the combination of the two methods is of interest.
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