Antenatal and intrapartum fetal evaluation

Antenatal and intrapartum fetal monitoring aim to identify the beginning of the process of fetal hypoxia before irreversible fetal damage has taken place. Fetal movement counting by the mother has not been reported to be of any benefit. The biophysical profile score, incorporating ultrasound and fetal heart rate monitoring, has not been proven to reduce perinatal mortality in randomized trials. Doppler ultrasound allows the exploration of the perfusion of different fetal organ systems and provides data on possible hypoxia and fetal anaemia. Maternal uterine artery Doppler can be used to select women with a high risk for intrauterine growth restriction and pre-eclampsia but does not directly provide information on fetal status. Umbilical artery Doppler has been shown to reduce perinatal mortality significantly in high-risk pregnancies (but not in low-risk women). Adding middle cerebral artery Doppler to umbilical artery Doppler does not increase accuracy for detecting adverse perinatal outcome. Ductus venosus Doppler demonstrates moderate value in diagnosing fetal compromise; it is not known whether its use adds any value to umbilical artery Doppler alone. Cardiotocography (CTG) reflects the interaction between the fetal brain and peripheral cardiovascular system. Prelabour routine use of CTG in low-risk pregnancies has not been proven to improve outcome; computerized CTG significantly reduces perinatal mortality in high-risk pregnancies. Monitoring the fetus during labour with intermittent auscultation has not been compared to no monitoring at all; when compared with CTG no difference in perinatal mortality or cerebral palsy has been noted. CTG does lower neonatal seizures and is accompanied by a statistically non-significant rise in caesarean delivery. Fetal blood sampling to detect fetal pH and base deficit lowers caesarean delivery rate and neonatal convulsions when used in adjunct to CTG. Determination of fetal scalp lactate has not been shown to have an effect on neonatal outcome or on the rate of instrumental deliveries but is less often hampered by technical failure than fetal scalp pH. Analysis of the ST segment of the fetal ECG (STAN®) in combination with CTG during labour results in fewer vaginal operative deliveries, less need for neonatal intensive care, and less use of fetal blood sampling during labour, without a change in fetal metabolic acidosis when compared to CTG alone.