ABSTRACT
It is not always possible or feasible to perform routine umbilical artery blood sampling
at birth. This study was undertaken to assess the accuracy of selective remote umbilical
arterial blood analysis to retrospectively predict the original birth pH of any newborn.
Umbilical arterial blood samples were obtained in two preheparinized syringes immediately
following 1007 deliveries. One sample was analyzed within 60 minutes of delivery.
The other was placed on ice and later analyzed at variable time intervals up to 180
hours postpartum. The results of each remote analysis were adjusted using a previously
published regression equation to accurately identify which new-borns had pH values
< 7.00, ≤ 7.10, or < 7.20 at birth. Among the 1007 newborns, there were 14 (1.3%),
44 (4.3%), and 187 (18.5%) who had pH values < 7.00, ≤ 7.10, and < 7.20, respectively,
at birth. Remote umbilical arterial samples analyzed within 72 hours of delivery correctly
identified newborns with an original pH < 7.00, ≤ 7.10, or < 7.20 with: (1) a sensitivity
of 100, 82, and 84%, respectively; (2) positive predictive values of 100, 93, and
66%, respectively; and (3) a test efficiency of 100, 99, and 89%, respectively. Up
to 72 hours after delivery, remote umbilical arterial blood pH analysis can be reliably
used to accurately identify the newborn that was acidotic at birth.
Keywords
Remote umbilical artery acid-base determination - neonatal acidosis
