Diagnosis of conjoined twins before 16 weeks' gestation: the 4-year experience of one medical center.

BACKGROUND: Descriptions of the rarely occurring condition of conjoined twins are sparse. METHODS: We report a case series of four conjoined twin pregnancies diagnosed up to 16 weeks of gestation. One was in a quadruplet in vitro fertilization intracytoplasmic sperm injection (IVF-ICSI) pregnancy of cryopreserved embryos and the others were spontaneous conceptions. Three were thoracopagus and had increased nuchal translucency (NT) or big nuchal cysts and one was omphalopagus. RESULTS: All the three affected twin pregnancies were terminated by cervical dilatation and uterine evacuation. In another case, selective fetal reduction, shortly followed by embryo reduction to singleton was performed. Histological analysis of one case revealed dissimilar gender. No further cytogenetic or molecular studies were conducted by parental request. The pathophysiology of increased NT, subcutaneous edema or nuchal cysts in thoracopagus conjoined twins, the possible embryonic events that may lead to dizygotic conjoined twins and the clinical management of conjoined twins in sets of multiple gestation are discussed. CONCLUSIONS: The current case series illustrates that there are many problems related to this rare, but intriguing, accident of nature that still need to be overcome.