Parapagus dicephalus dibrachius dipus conjoined twin case

DISCUSSION_ Conjoined twins occur in approximately 1 percent of monoamniotic monochorionic monozygotic twins.1 The reported global prevalence ranges from 1:50,000 to 1:100,000 births.1-2 Of the small number of conjoined twins born alive, there is a 30 percent mortality rate within the first 24 hours of life.1 Overall, there is a 2:1 female predominance of conjoined twins. The former attributes the development of conjoined twins to incomplete division of the developing embryo, while the latter argues that all eight types occur by secondary fusion of two embryonic discs beyond the 13th day post-conception.3 Conjoined twins are divided into two main groups, ventral and dorsal, based on the location of embryonic disc union. Prepared by Mr. Byers while a 4th year medical student at the University of Arizona College of Medicine, Phoenix, AZ.; Dr. Young while a Radiology Resident, and Dr. Connell while serving as the Radiology Residency Program Director, Associate Professor of Radiology, and Section Chief of Ultrasound at Maricopa Medical Center, Phoenix, AZ.