A bicentric cohort study comparing umbilical cord and neonatal blood samples for chemistry tests at birth

Objectives To compare umbilical cord and neonatal blood for chemistry tests upon admission to the neonatal intensive care unit (NICU). Methods We designed a prospective, bicentric cohort study enrolling newborns (n = 71) with a planned admission to the NICU. Paired samples of umbilical cord and infant's blood were collected, analyzed, and compared. An intraclass correlation coefficient (ICC) was calculated for a repeatability analysis, and a Bland-Altman analysis was performed to assess the agreement between the 2 methods of sampling. The multivariable coefficient of determination (R-2) was reported to quantify the degree of correlation between the methods of measurement. Results The degree of agreement between the 2 sampling methods for chemistry tests was fair to good for high-sensitivity C-reactive protein (ICC = 0.79 [95% CI, 0.67-0.87]), phosphorus (ICC = 0.83 [95% CI, 0.73-0.90]), and albumin (ICC = 0.76 [95% CI, 0.60-0.86]), while it was good to excellent for & gamma;-glutamyl transpeptidase (ICC = 0.95 [95% CI, 0.88-0.98]) and procalcitonin (ICC = 0.90 [95% CI, 0.76-0.96]). Conclusions Umbilical cord blood is a reliable replacement source for multiple chemistry tests at birth. This sampling method has the potential to minimize the risk of transfusion-requiring anemia in newborns and its associated complications. Further studies are warranted to assess the efficacy of this strategy in improving neonatal outcomes.