title: Evaluation of the direct antiglobulin (Coombs') test for identifying newborns at risk for hemolysis as determined by end-tidal carbon monoxide concentration (ETCOc); and comparison of the Coombs' test with ETCOc for detecting significant jaundice.
abstract: OBJECTIVE
  First, to determine the sensitivity, specificity, and positive predictive value (PPV) of the direct antiglobulin test (DAT) for significant hemolysis in the neonate, as referenced to end-tidal carbon monoxide, the criterion standard for estimating the rate of hemolysis; and second, to evaluate the predictive value of the two procedures for significant jaundice.
  
  
  METHODS
  Consecutive term newborns admitted to the nursery of an inner-city university hospital over a 15-week period. DAT screening by the Blood Bank was performed on all. End-tidal carbon monoxide levels were obtained at 12+/-6 and at 24+/-6 hours of age. Infants of nonsmoking mothers whose 12-hour exhaled carbon monoxide level was > or = 95th percentile were defined as having significant hemolysis.
  
  
  RESULTS
  n=660; DAT was positive in 23 (3.5%). Using the 12-hour end-tidal carbon monoxide > or = 3.2 microl/l (> or = 95th percentile) as reference (n=499 nonsmokers), the sensitivity of the DAT was 38.5% (10 of 26) and specificity 98.5% (466 of 473) for the detection of significant hemolysis. The PPV of the DAT for significant hemolysis at 12 hours was 58.8% (10 of 17). For significant jaundice the PPV of end-tidal carbon monoxide was greater than that for DAT (65.4% vs 52.9%), although not statistically so (p=0.25). The negative predictive values were similar.
  
  
  CONCLUSIONS
  DAT fails to identify over half of the cases of significant hemolysis that are diagnosed by end-tidal carbon monoxide. A neonate with a positive DAT has about a 59% chance of having significant hemolysis. End-tidal carbon monoxide may also provide a more sensitive index for predicting significant jaundice.
authors.affiliation: Department of Pediatrics, Children's Hospital, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: Marguerite
authors.initials: M
authors.lastname: Herschel
authors.forename: Theodore
authors.initials: T
authors.lastname: Karrison
authors.forename: Ming
authors.initials: M
authors.lastname: Wen
authors.forename: Leslie
authors.initials: L
authors.lastname: Caldarelli
authors.forename: Beverly
authors.initials: B
authors.lastname: Baron
mesh_terms: D001944:Breath Tests; D002248:Carbon Monoxide / Q000032:analysis*; D003298:Coombs Test; D004899:Erythroblastosis, Fetal / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007567:Jaundice, Neonatal / Q000175:diagnosis*; D008297:Male; D012680:Sensitivity and Specificity
chemical_list: D002248:Carbon Monoxide