Introduction

>  Intrapartum fetal surveillance frequently involves the use of a cardiotocograph (CTG).

>  The CTG is an electronic method of simultaneously recording fetal heart rate (FHR), fetal movements and uterine contractions to identify the probability of fetal hypoxia (Pattison and McCowan 2006).  In nearly half of all CTG tracings, an abnormal fetal heart rate is observed, but only a small proportion of these fetuses are actually hypoxic (Wiberg-Itzel et al. 2008)

>  The use of fetal blood sampling (either pH or lactate) in such cases may reduce intervention rates (e.g. caesarean section) associated with the use of cardiotocography alone (RANZCOG 2006)

>  If fetal blood sampling is performed, the scalp pH or lactate result should be interpreted taking into account any previous measurement, the rate of progress in labour and other clinical circumstances (RANZCOG 2006)

>  Metabolic acidaemia occurs in 2 % of all births.  Over 90 % of these infants will not develop cerebral palsy (RCOG 2001)