Umbilical artery pH measurement is SUPERFLUOUS!

Abstract

In their Table I, ”Umbilical artery pH values reported in literature,” Nagel et al. (Nagel HTC, Vandenbussche FPHA, Oepkes D, Jennekens-Schinkel A, Laan LAEM, Gravenhorst JB. Follow-up of children born with an umbilical arterial blood pH <7. Am J Obstet Gynecol 1995;173:1758-64) neglected to mention that altitude affects the umbilical artery pH value. In 11,203 births at 5280 feet (Denver), we reported umbilical artery pH values to be 7.31 ± 0.064.1Goodlin RC Freedman WL McFee JG Winter SD The neonate with unexpected acidemia.J Reprod Med. 1994; 39: 97-100PubMed Google Scholar Yancey et al.2Yancey MK Moore J Brady K Milligan D Strampel W The effect of altitude on umbilical cord blood gases.Obstet Gynecol. 1992; 79: 571-573PubMed Google Scholar found in 150 cases at an altitude of 5900 feet that the umbilical artery pH was 7.32 ± 0.05, both values being higher than those reported in the authors' Table I. In contrast to the results of Nagel et al., we found that most cases of severe fetal acidemia were unexplained (because the labors and neonates appeared normal) and that routinely determining the umbilical artery pH did not affect clinical management.1Goodlin RC Freedman WL McFee JG Winter SD The neonate with unexpected acidemia.J Reprod Med. 1994; 39: 97-100PubMed Google Scholar Contrary to American definitions,3American College of Obstetricians and Gynecologists Umbilical artery blood acid-base balance. The College, Washington (DC)1995Google Scholar the authors use the terms acidosis and acidemia interchangeably. In 1959 Kaiser4Kaiser IH The significance of fetal acidosis.Am J Obstet Gynecol. 1959; 77: 573-584PubMed Scopus (4) Google Scholar suggested that only estimation of the neonate's condition could make possible a proper evaluation of the acidemia. The current study of Nagel et al. supports Kaiser's earlier suggestion that umbilical artery pH alone is of little value. Maternal pH is the most important determinant of fetal pH but is seldom measured in cases of fetal acidemia. Also, it is only an assumption that a fetus is unable to correct a labor-induced metabolic acidemia before birth. That umbilical artery pH is a poor prediction of immediate or subsequent neurologic function is therefore understandable.5Goodlin RC Do concepts of causes and prevention of cerebral palsy require revision?.Am J Obstet Gynecol. 1995; 172: 1830-1836Abstract Full Text PDF PubMed Scopus (16) Google Scholar The author's assertion that umbilical artery pH measurement is not superfluous should be challenged. 6/8/74263