title: The Northwestern Twin Chorionicity Study: I. Discordant inflammatory findings that are related to chorionicity in presenting versus nonpresenting twins.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the association between chorionicity and discordant chorioamnionitis and funisitis in twin gestations.
  
  
  METHODS
  This was a retrospective analysis of 1156 twin placentas with a standardized diagnosis of chorionicity, chorioamnionitis, and funisitis for comparison between presenting and nonpresenting twins with dichorionic-separate, dichorionic-fused, and monochorionic placentas.
  
  
  RESULTS
  Frequencies of chorioamnionitis in the nonpresenting twin were significantly lower in dichorionic placentas (odds ratio, 0.4; 95% CI, 0.3, 0.6, in dichorionic-separate placentas; odds ratio, 0.5; 95% CI, 0.3, 0.8, in dichorionic-fused placentas) compared with monochorionic placentas. The frequency of advanced inflammation (ie, chorioamnionitis with funisitis) was significantly lower in the nonpresenting twin than in the presenting twin, but only in dichorionic-separate placentas (odds ratio, 0.2; 95% CI, 0.1, 0.4).
  
  
  CONCLUSIONS
  Dichorionic placentas confer significant protection against the spread of chorioamnionitis from the presenting to the nonpresenting gestational sac. In the more advanced process that involves the umbilical cord, only the subset of separate dichorionic placentas confers this protective effect against the spread of inflammation.
authors.affiliation: Department of Obstetrics and Gynecology, Northwestern University Medical School, Chicago, Ill, USA.
authors.forename: Duong T
authors.initials: DT
authors.lastname: Phung
authors.forename: Isaac
authors.initials: I
authors.lastname: Blickstein
authors.forename: Ran D
authors.initials: RD
authors.lastname: Goldman
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Machin
authors.forename: Roseanne D
authors.initials: RD
authors.lastname: LoSasso
authors.forename: Louis G
authors.initials: LG
authors.lastname: Keith
mesh_terms: D000328:Adult; D002821:Chorioamnionitis / Q000473:pathology* / Q000517:prevention & control; D015331:Cohort Studies; D018562:Disease Transmission, Infectious / Q000517:prevention & control; D005260:Female; D005315:Fetal Diseases / Q000473:pathology* / Q000517:prevention & control; D006801:Humans; D007249:Inflammation / Q000473:pathology / Q000517:prevention & control; D016017:Odds Ratio; D010920:Placenta / Q000473:pathology; D011247:Pregnancy; D012189:Retrospective Studies; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D014470:Umbilical Cord / Q000473:pathology*