Umbilical cord blood gas analysis

Umbilical blood sampling at delivery has emerged as the most objective measurement of utero placental function and fetal oxygenation/acid-base status at birth. Most depressed newborns completely normal umbilical cord blood gas values. In contrast to the poor specificity of fetal heart rate monitoring and Apgar scores, umbilical cord blood gas analysis defines the exact acid-base balance and differentiates perinatal asphyxia from other conditions leading to immediate newborn depression and adverse neurologic sequelae. This article discusses normal cord blood gas values, pertinent acid-base physiology, factors affecting these values, and the advantages of universal versus selective sampling strategies.