Monochorionic (MC) pregnancies have higher rates of fetal morbidity and mortality when compared to dichorionic (DC) ones. Therefore, the early diagnostic of chorionicity is of great importance. Monochorionic pregnancies have specific complications such as twin to twin transfusion syndrome (TTTS), selective fetal growth restriction (sFGR), twin anemia polycythemia sequence (TAPS), and twin reversed arterial perfusion sequence (TRAPS). MC pregnancies have several unique and serious complications that contribute to a perinatal mortality rate of 11%. The pathophysiology of most of these complications is related to the placental angio-architecture, and it results from an unbalanced perfusion between the fetuses. The screening of TTTS starts in 16 weeks with a sonographic follow-up every 2 weeks. In the last decade, there was an improvement in the treatment of TTTS. With the advent of the fetoscopic laser photocoagulation (FLPC), there was a drastic increase in the survival rate of the fetuses with TTTS when compared with serial amnioreduction. Besides that, in TRAPS, fetoscopic procedures such as cord occlusion improve the outcome of the normal fetus. We will also discuss sFGR and its classification and management. The aim of this chapter is to review the most important complications in MC pregnancies.
Part of the book: Multiple Pregnancy