Monochorionic diamniotic quadruplet pregnancy: physical models from prenatal three-dimensional ultrasound and magnetic resonance imaging data

Introduction

Monozygotic (MZ) twins are relatively rare, with an incidence worldwide of about 0.40–0.45% after non-stimulated in-vivo conception1. The rate of MZ twinning after assisted reproductive technology (ART) is estimated to be between two and 12 times higher than for natural conception2. Higher-order multiple pregnancies carry significantly increased risks of fetal morbidity and mortality compared with the baseline risks of a twin pregnancy. Additional risks are also associated with monochorionicity. Simultaneous division of two transferred embryos in ART is a rare event (< 0.16% of all pregnancies) and only a few cases have been reported in the literature3. Several reports refer to higher-order multiple pregnancies as a result of the increasing use of ART in recent years, including quadruplet pregnancies4. However, embryo reduction is performed in most cases and good outcomes in higher-order multiple pregnancies from ART are scarcely reported. We present here a case of successful pregnancy after simultaneous division of two transferred embryos, resulting in two sets of monochorionic diamniotic twin pregnancies. Three-dimensional (3D) virtual and physical models of the pregnancy were created using prenatal ultrasound and magnetic resonance imaging (MRI) data.