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

- VV anastomoses are detected in 27% of MC placentas.
- The prevalence of TTTS in MC placentas with VV anastomoses was significantly higher.
- The presence of VV anastomoses is correlated with perinatal mortality.
- The presence of VV anastomoses is an independent risk factor for TTTS.
- VV anastomoses are not an independent risk factor for perinatal mortality.

IntroductionThe 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.MethodsAll 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 DiscussionA 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.ConclusionThe 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.