Chapter 25 - Vanishing twin syndrome and long-term outcome

Summary

This chapter addresses the prevalence of vanishing twins with considerations of the early implantation process including possible pathological mechanisms of the vanishing twin and the vanishing embryo syndrome. The precise pathophysiological mechanism of the vanishing twin is still unknown, but early pregnancy disappearance seems to involve resorption and/or formation of a blighted ovum or fetus papyraceus and several explanations are offered. Early vanishing twins including incipient twins following the transfer of two or more embryos may increase the incidence of first-trimester bleeding in assisted reproductive technologies (ART) pregnancies. Studies have shown that children after intrauterine insemination with ovarian stimulation and in-vitro fertilization (IVF) children have similar neonatal outcome indicating that the ovarian stimulation significantly influences the outcome. In a clinical frame with a double-embryo transfer policy, vanishing twin pregnancies account for about 10% of all singleton births.