Fetal scalp blood sampling for pH and lactate measurement during labour

The wide use of continuous of fetal heart rate monitoring (FHR) since the seventies has been accompanied by an increase in cesarean delivery rates, without any decrease in cerebral palsy rate. Second line methods of fetal monitoring have been developed in order to better identify fetuses truly at risk of intrapartum asphyxia. The use of fetal scalp blood sampling (FBS) for fetal monitoring seems logical since neonatal acidosis is one of the major criteria of birth asphyxia. Studies show that the use of FBS reduces the increase in cesarean deliveries associated with the use of continuous FHR monitoring. However, FBS is invasive, non continuous and technically uneasy, with a rather high rate of failed blood samplings. Fetal scalp lactates measurement by micromethod requires a much smaller volume of blood. Although a wider assessment is required, the predictive value of fetal blood lactates seems to be similar to that of fetal scalp blood pH.