title: Clinical usefulness of white blood cell count after cesarean delivery.
abstract: OBJECTIVE
  To examine changes in white blood cell (WBC) count after cesarean and estimate risk of postoperative infection.
  
  
  METHODS
  We measured complete blood cell counts at admission and on postoperative day 1 for 458 women who had cesareans. Information from charts was abstracted, and definitions of infectious outcomes and fever were applied by three physicians masked to laboratory results. We examined changes in absolute and relative WBC counts by labor status. Likelihood ratios for postoperative infection were calculated for statistically distinct categories of percentage changes.
  
  
  RESULTS
  We excluded 60 women with chorioamnionitis. Of the remainder, 34 (8.5%) developed endometritis and three (0.8%) pneumonia. Women who labored before cesarean (n = 198) had higher antepartum (P <.001) and postoperative day 1 (P <.001) WBC counts than those who did not (n = 200). However, change in WBC count after cesarean relative to antepartum was similar for both groups (P =.41), averaging a 22% increase. We grouped percentage changes into the following three levels: up to 24%, 25-99%, and at least 100%. The lowest level (n = 246) corresponded to a category-specific likelihood ratio for diagnosis of serious postpartum infection of 0. 5 (95% confidence interval [CI] 0.3, 0.8), the midlevel (n = 141) to a category-specific likelihood ratio of 1.7 (95% CI 1.2, 2.3), and the highest level (n = 11) to a category-specific likelihood ratio of 5.8 (95% CI 1.8, 18.7).
  
  
  CONCLUSIONS
  Labor influenced postcesarean WBC counts but did not obscure changes associated with infection. Information gained from changes in WBC counts can be used to assess risk of infection.
authors.affiliation: Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, North Carolina 27599-7590, USA. khartman@med.unc.edu
authors.forename: K E
authors.initials: KE
authors.lastname: Hartmann
authors.forename: K E
authors.initials: KE
authors.lastname: Barrett
authors.forename: V C
authors.initials: VC
authors.lastname: Reid
authors.forename: M J
authors.initials: MJ
authors.lastname: McMahon
authors.forename: W C
authors.initials: WC
authors.lastname: Miller
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000009:adverse effects*; D004716:Endometritis / Q000097:blood; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D016013:Likelihood Functions; D018410:Pneumonia, Bacterial / Q000097:blood; D011183:Postoperative Complications / Q000097:blood* / Q000209:etiology*; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011247:Pregnancy; D011645:Puerperal Infection / Q000097:blood* / Q000209:etiology*