Comparison of Placental and Neonatal Admission Complete Blood Cell Count and Blood Cultures.

BACKGROUND: The utilization of placental blood for neonatal admission laboratory tests, specifically the complete blood cell (CBC) count and blood culture, has the potential to delay the onset of anemia of prematurity and intraventricular hemorrhage, frequency of blood transfusions and associated complications, and painful procedures related to laboratory sampling.

PURPOSE: To determine the feasibility of drawing neonatal admission laboratory tests from the placenta rather than the neonate and to compare CBC count and blood culture results.

METHODS: All infants less than 35 weeks' gestational age and all term infants with a maternal history of chorioamnionitis or untreated, positive group B Streptococcus status were eligible to participate. Participating infants had paired CBC count and blood cultures obtained from the placenta and the infant.

RESULTS: All CBC count outcomes were significantly, positively correlated between placental and infant blood (all Ps < .05). The paired white blood cells, neutrophils, and lymphocytes were strongly correlated (r = 0.761, r = 0.797, and r = 0.815, respectively), whereas the hemoglobin, hematocrit, platelet, and eosinophils were moderately correlated (r = 0.554, r = 0.545, r = 0.563, and r = 0.478, respectively). Monocytes and basophils were only weakly correlated (r = 0.373 and r = 0.217, respectively). There were 13 (93%) pairs where placental blood culture was positive but the direct infant draw blood culture was negative, and 1 (7%) pair where the placental culture was negative but the direct infant draw blood culture was positive.

IMPLICATIONS FOR PRACTICE: The results of this and other studies suggest that placental blood can be reliably used to obtain neonatal admission CBC count and blood cultures.

IMPLICATIONS FOR RESEARCH: Further research is needed regarding the prevention of blood culture contamination, especially in vaginally delivered placentas. Institutions that adopt this procedure should perform quality improvement initiatives to monitor outcomes and add to the growing body of literature on the utilization of placental blood for neonatal admission laboratory tests.