Selective reduction in multiple gestations.

The frequency of multiple gestations has increased dramatically. Twins and higher order multiple gestations have pregnancies with increased risks for almost every complication of pregnancy, especially preterm labour, preterm delivery, and congenital anomalies. Monochorionic twins, by virtue of the unique placental angioarchitecture, are at risk for additional complications, such as severe discordant malformations, twin reversed arterial perfusion sequence, twin-to-twin transfusion syndrome or severe selective intrauterine growth restriction. These complications create unique challenges to those who manage multiple pregnancies. Reduction of higher order multiple pregnancies is on option to reduce pregnancy related risks and improve overall outcomes. Selective termination in complex monochorionic pregnancies can be lifesaving for the co-twin by preventing intrauterine demise or extreme prematurity. It is critical, however, to determine chorionicity before considering any approach to selective reduction. Techniques applied to dichorionic twins cannot be directly translated to cases involving monochorionic twins.