Fetal blood sampling in labor

Abstract

Cardiotocography is the most widely used method to monitor fetal well-being during labor. It has been shown that this technology is affected by a large intra and interobserver variability, that reduces its reliability. Moreover, it should be remembered that CTG is in condition to detect early fetal heart rate patterns that may indicate fetal hypoxaemia but it is not able to assess precisely the level of fetal compromise. This assessment can be done by examining fetal blood for pH that can be easily obtained in labor. If present, the level of acidemia, is established by measuring the pH which can be of practical use in clinical management. Values above 7.24 are considered normal, and pH values lower than 7.20 are expression of fetal acidemia requiring a quick delivery. The technique of FBS can be easily performed with very few complications. The main indication is one of the abnormal or suspicious CTG patterns. By using FBS is a complementary diagnostic tool to CTG it is possible to reduce the number of false positive thus reducing the number of unnecessary obstetrical interventions.