Re-evaluation of cord blood arterial and venous reference ranges for pH, pO(2), pCO(2), according to spontaneous or cesarean delivery.

Umbilical cord blood gas analysis (pO(2) and pCO(2)) is now recommended in all high-risk baby deliveries and in some centers it is performed routinely following all deliveries. The aim of this study was to re-evaluate cord blood arterial and venous reference ranges for pH, pO(2), pCO(2) in newborns, delivered by spontaneous vaginal delivery (SVD) and by cesarean section (CS) performed in Faculty Hospital Motol. Two groups of subjects were selected for the study. Group I consisted of 303 newborns with SVD. Group II consisted of 189 newborns delivered by cesarean section. Cord blood samples were analyzed for standard blood gas and pH, using the analytical device Rapid Lab 845 and Rapid Lab 865. We obtained reference values expressed as range (lower and upper reference value expressed as 2.5 and 97.5 percentiles) for cord blood in newborns with SVD: arterial cord blood: pH=7.01-7.39; pCO(2)=4.12-11.45 kPa; pO(2)=1.49-5.06 kPa; venous cord blood: pH=7.06-7.44; pCO(2)=3.33-9.85 kPa; pO(2)=1.80-6.29 kPa. We also obtained reference values for cord blood in newborns delivered by CS: arterial cord blood: pH=7.05-7.39; pCO(2)=5.01-10.60 kPa; pO(2)=1.17-5.94 kPa; venous cord blood: pH=7.10-7.42; pCO(2)=3.88-9.36 kPa; pO(2)=1.98-7.23 kPa. Re-evaluated reference ranges play essential role in monitoring conditions of newborns with spontaneous and caesarean delivery. J. Clin. Lab. Anal. 24:300-304, 2010.