J Med Assoc Thai. 2016 May;99(5):611-7.

Reference Values for Umbilical Cord Blood Gases of Newborns Delivered by Elective Cesarean Section.

Manomayangkul K, Siriussawakul A, Nimmannit A, Yuyen T, Ngerncham S, Reesukumal K.

Abstract

BACKGROUND:

Umbilical cord blood gas values are better indicators of perinatal asphyxia than Apgar scores. Many studies have reported normal ranges of umbilical cord blood gases, which vary greatly due to many factors. This study aimed to establish the reference values of umbilical cord blood gases of normal cesarean newborns in a university hospital setting.

MATERIAL AND METHOD:

Blood samples from the umbilical artery and vein were collected from 160 newborns delivered by elective cesarean section. The indications for caesarean section were not due to fetal distress, intrauterine growth retardation, or non-reassuring fetal heart rate. The blood samples were collected immediately after birth in the operating room and then sent for blood-gas analysis. The blood-gas values were statistically analyzed and reported.

RESULTS:

The cord blood collected from 160 newborns was analyzed in this study. Seventy-eight percent (115) of the parturients were hypotensive before delivery. All Apgar scores at one and five minutes after delivery were at least 7. The calculated reference range of the umbilical arterial pH was 7.18-7.42, of pO₂was 6.43-29.43 mmHg, of pCO₂was 33.44-66.56 mmHg, and of HCO₃was 15.60-30.70 mEq/L. The reference range obtained for the umbilical venous pH was 7.28-7.44,for pO₂was 13.97-37.13 mmHg, for pCO₂was 30.70-57.0 mmHg, and for HCO₃was 18.50-29.90 mEq/L.

CONCLUSION:

The study determined normal reference values as a result of umbilical cord blood gas analyses.