Determination of Foetal Scalp Blood Sampling pH as an Indicator of Loss of Foetal Well-Being in Women Undergoing Caesarean Section

Abstract

Asphyxia during birth is one of the three leading causes of neonatal morbidity and mortality among newborns carried to term. The objective of this study was to evaluate the measurement of the foetal scalp blood pH as a measure of foetal status, evaluating: cord gases, meconium-stained fluid, APGAR score or the need for neonatal resuscitation in pregnant women undergoing caesarean sections. A cross-sectional study was carried out over a period of 5 years (2017-2021) at the Hospital de Poniente (southern Spain). A total of 127 pregnant women participated from whom a foetal scalp blood pH sample was taken and used to indicate the need for an urgent caesarean section. The results showed a correlation between the pH of the scalp blood and the pH of the umbilical cord artery, umbilical cord vein (Rho of Spearman arterial pH: 0.64, p < 0.001; Rho of Spearman venous pH: 0.58, p < 0.001) and the APGAR test one minute after delivery (Spearman's Rho coefficient of 0.33, p < 0.01). These results suggest that the foetal scalp pH should not be considered a foolproof method to indicate an urgent caesarean section. Foetal scalp pH sampling can be used as a complementary test, in conjunction with cardiotocography, to indicate whether an emergency caesarean section is necessary due to loss of foetal well-being.