Correlation of the One-Minute Apgar Score and the pH Value of Umbilical Arterial Blood

Abstract

The one-minute Apgar score, proven useful for rapid assessment of the neonate, is often poorly correlated with other indicators of intrauterine well-being. Fetal asphyxia is directly associated with neonatal acidosis. A low Apgar score in the face of normal pH and base deficit does not, therefore, indicate an asphyxiated infant. We performed a study at Vanderbilt University Hospital to ascertain the feasibility of combining the pH value of umbilical arterial blood with the one-minute Apgar score for neonatal assessment. The pH values and Apgar scores were obtained on 172 singleton neonates. When the Apgar score was less than 7, over one half (56%) of the neonates had a normal pH value. Of this group 46% had undergone intubation and nasopharyngeal suctioning, procedures known to be associated with lowered Apgar scores. We recommend, therefore, that neonates with a one-minute Apgar score of less than 7 be further evaluated with umbilical arterial blood gas studies to ascertain the presence of acidosis and to differentiate between metabolic and respiratory acidosis. More precise confirmation of the diagnosis of fetal distress and neonatal asphyxia, for both treatment and medicolegal purposes, is possible with this information.