title: Correlation between veno-venous anastomoses, TTTS and perinatal mortality in monochorionic twin pregnancies.
abstract: BACKGROUND
  The clinical significance of veno-venous (VV) anastomoses in monochorionic (MC) placentas remains inconclusive and controversial. The purpose of this study was to investigate the correlation between the presence of VV anastomoses and clinical outcome in a large cohort of MC twin pregnancies.
  
  
  METHODS
  All MC placentas injected with colored dye from 2002 to 2014 were included in the study. We excluded MC pregnancies managed with fetoscopic laser surgery.
  
  
  CONCLUSIONS
  A total of 384 MC placentas were analyzed. VV anastomoses were detected in 27% (104/384) of MC placentas. The prevalence of twin-twin transfusion syndrome (TTTS) in MC placentas with VV anastomoses was significantly higher compared to MC placentas without VV anastomoses, 20% (21/104) versus 10% (29/280), respectively (P = .01). The overall perinatal mortality in MC twins with and without VV anastomoses was 16% versus 10%, respectively (P = .02). Risk factor analysis showed the presence of VV anastomoses was associated with perinatal mortality (P = .02; odds ratio (OR): 1.76; 95% confidence interval (CI): 1.11-2.79), but was not an independent risk factor for perinatal mortality (P = .26, OR: .66; 95% CI: .33-1.35) in MC twin pregnancies. However, VV anastomoses was associated with and was an independent risk factor for TTTS (P = .00, OR: 3.59; 95% CI: 1.72-7.47). VV anastomoses-related perinatal mortality may be due to the high rate of TTTS in MC twins with VV anastomoses.
  
  
  CONCLUSIONS
  The presence of VV anastomoses is correlated with TTTS and perinatal mortality, but is not an independent risk factor for perinatal mortality in MC twin pregnancies.
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: S F
authors.initials: SF
authors.lastname: de Villiers
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: d.zhao@lumc.nl.
authors.forename: D P
authors.initials: DP
authors.lastname: Zhao
authors.affiliation: Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Cohen
authors.affiliation: Department of Medical Statistics, Leiden University Medical Centre, Leiden, The Netherlands.
authors.forename: E W
authors.initials: EW
authors.lastname: van Zwet
authors.affiliation: Division of Fetal Medicine, Department of Obstetrics, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China.
authors.forename: T
authors.initials: T
authors.lastname: Duan
authors.affiliation: Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Oepkes
authors.affiliation: Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Lopriore
mesh_terms: D005260:Female; D005330:Fetofetal Transfusion / Q000453:epidemiology*; D006801:Humans; D007231:Infant, Newborn; D009426:Netherlands / Q000453:epidemiology; D054238:Perinatal Mortality; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D059285:Pregnancy, Twin / Q000706:statistics & numerical data*; D014430:Twins, Monozygotic; D016157:Vascular Fistula / Q000453:epidemiology*
keywords: Monochorionic twins; Perinatal mortality; Twin-twin transfusion syndrome; Veno-venous anastomoses