Ischiopagi

Ischiopagi comes from the greek word ischio- meaning hip (ilium) and -pagus meaning fixed or united. It is the medical term used for conjoined twins (Class V) who are united at the pelvis. The twins are classically joined with the vertebral axis at 180°. However, the most frequent cases usually structures the Ischiopagus twins with two separate spines forming a lateral angle smaller than 90°. The conjoined twins usually have four arms; two, three or four legs; and typically one external genitalia and anus.

It is mostly confused with pygopagus where the twins are joined ventrally at the abdomen and umbilicus whereas Ischiopagus twins are joined dorsally at the sacrum and coccyx. Parapagus is also similar to Ischiopagus, however, conjoined parapagus twins share one heart whereas Ischiopagus have separate functioning hearts.