Abstract

OBJECTIVES: To explore the outcome of monochorionic monoamniotic (MCMA) twin pregnancies affected by twin-to-twin transfusion syndrome (TTTS). METHODS: Medline and Embase databases were searched. The primary outcome was intra-uterine death (IUD); secondary outcomes were: miscarriage, single IUD, double IUD, neonatal death (NND), perinatal death (PND), presence of at least one or both survivors and preterm birth (PTB) <32 weeks of gestation. All these outcomes were assessed in MCMA twins affected by TTTS not undergoing intervention and in those treated with amniodrainage, laser therapy and cord occlusion. Sub-group analysis including cases diagnosed <24 weeks of gestation was also performed. Random-effect meta-analyses of proportions were used to analyze the data. RESULTS: Seventeen retrospective cohort studies (890 MCMA twin pregnancies, 46 affected by TTTS) were included in the review while there was no randomised trial comparing the different management options in MCMA twin pregnancies complicated by TTTS. In cases not undergoing intervention, miscarriage occurred in 10.7% of fetuses, while the incidence of IUD, NND and PND was 24.3%, 13.5% and 32.4% respectively. PTB complicated 54.0% of these pregnancies. In cases treated by laser surgery, the incidence of miscarriage, IUD, NND and PND was 19.6%, 27.4%, 7.4% and 35.9% respectively. The incidence of PTB <32 weeks of gestation was 64.9%. In cases treated with amniodrainage, the incidence of IUD, NND and PND was 30.3%, 19.1% and 35.9% respectively. PTB complicated 78.1% of cases. Analysis of cases undergoing cord occlusion was affected by the very small number of included cases. Miscarriage occurred in 19.2%, while there was no IUD or NND of the surviving twin. PTB <32 weeks occurred in 50.0% of cases. CONCLUSION: MCMA twin pregnancies complicated by TTTS are at high risk of perinatal mortality and PTB. Further studies are needed in order to elucidate the optimal type of prenatal treatment in these pregnancies. This article is protected by copyright. All rights reserved.