Two-headed twin in a triplet pregnancy after in vitro fertilization - A case report and review of the literature

Conjoined twins (CT) in triplet pregnancies are especially rare, approximately less than one in a million deliveries. Purpose: For better understanding of such malformations the authors performed a review of the literature published in the era of sonographic imaging, concerning CT in triplet gestations, as well as in the multiple pregnancies conceived by artificial reproduction (assisted reproductive techniques, ART). Case Report: A 26-year-old primigravida who underwent in vitro fertilization with embryo transfer (IVF-ET) was diagnosed with dichorionic, diamniotic triplet gestation. In the 33th week of pregnancy, a healthy male singleton was born, together with paraphagus dicephalus dibrachius dipus twins. Results: This is one of only a few cases reported in the literature of a lively born neonate with such malformations, its uniqueness even increased by the occurrence in triplet gestation conceived with ART. The literature reports three options for the triplet pregnancy with a CT: its continuation with an enhanced risk of premature delivery, termination of the entire gestation, or selective feticide of the CT. In the present case, although the defect was detected in the first trimester, no fetal reduction was performed and both infants were horn alive. No intervention was deemed appropriate as the healthy singleton was uneventfully delivered and discharged home. Conclusions: ART, such as IVF-ET, are related to a higher prevalence of monozygotic twins, implying that the procedure might also increase the occurrence of CT. Notwithstanding the rarity of CT in triplets, such gestations are a significant challenge for the proper diagnosis and maintenance.