Correlation between veno-venous anastomoses, TTTS and perinatal mortality in monochorionic twin pregnancies

Introduction: The clinical significance of veno-venous (W) anastomoses in monochorionic (MC) placentas remains inconclusive and controversial. The purpose of this study was to investigate the correlation between the presence of W 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. Results and Discussion: A total of 384 MC placentas were analyzed. W anastomoses were detected in 27% (104/384) of MC placentas. The prevalence of twin-twin transfusion syndrome (TTTS) in MC placentas with W 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 W 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, W anastomoses was associated with and was an independent risk factor for TTTS (P = .00, OR: 3.59; 95% CI: 1.72-7.47). W anastomoses-related perinatal mortality may be due to the high rate of TITS in MC twins with W anastomoses. Conclusion: The presence of W anastomoses is correlated with TITS and perinatal mortality, but is not an independent risk factor for perinatal mortality in MC twin pregnancies. (C) 2015 Elsevier Ltd. All rights reserved.