Foetal scalp blood sampling during labour for pH and lactate measurements. (January 2016)

• Record Type: Journal Article
• Authors: Carbonne, Bruno; Pons, Kelly; Maisonneuve, Emeline
• Is Part Of: Best practice & research. Volume 30(2016:Jan.)
• Page Start: 62
• Page End: 67
• Publication Date: 2016-01
• Subjects: foetal blood sampling -- scalp blood pH -- scalp blood lactates -- foetal asphyxia -- metabolic acidosis -- cerebral palsy; Gynecology -- Periodicals; Obstetrics -- Periodicals; Genital Diseases, Female; Obstetrics; Gynecology; Obstetrics; Periodicals; 618.05
• DOI: 10.1016/j.bpobgyn.2015.05.006
• Languages: English
• ISSNs: 1521-6934

Abstract

Abstract : Second-line methods of foetal monitoring have been developed in an attempt to reduce unnecessary interventions due to continuous cardiotocography (CTG), and to better identify foetuses that are at risk of intrapartum asphyxia. Very few studies directly compared CTG with foetal scalp blood (FBS) and CTG only. Only one randomised controlled trial (RCT) was published in the 1970s and had limited power to assess neonatal outcome. Direct and indirect comparisons conclude that FBS could reduce the number of caesarean deliveries associated with the use of continuous CTG. The main drawbacks of FBS are its invasive and discontinuous nature and the need for a sufficient volume of foetal blood for analysis, especially for pH measurement, resulting in failure rates reaching 10%. FBS for lactate measurement became popular with the design of test-strip devices, requiring <0.5 mL of foetal blood. RCTs showed similar outcomes with the use of FBS for lactates compared with pH in terms of obstetrical interventions and neonatal outcomes. In conclusion, there is some evidence that FBS reduces the need for operative deliveries. However, the evidence is limited with regard to actual standards, and large RCTs, directly comparing CTG only with CTG with FBS, are still needed. Highlights: Foetal blood sampling is used as a second-line technique in cases of abnormal foetal heart rate. Foetal blood sampling may reduce the need for operative deliveries. Intervention is indicated in cases of scalp blood pH < 7.20 or lactate > 4.8 mmol/L. The failure rate of foetal blood sampling is lower with lactate analysis. Large randomised controlled trials are still needed.