Table 1 Classification of conjoined twins according to the site of fusion
From: Prenatal diagnosis of non-janiceps type of cephalopagus conjoined twins: a case report
Types | Definitions |
|---|---|
Cephalopagus | Fused from head to umbilicus. One or two faces on either side of the fused head |
Thoracopagus | Face to face fusion involving upper thorax to upper abdomen with usually a common heart |
Omphalopagus | Fused at the umbilical level and share abdominal organs but never the heart |
Ischiopagus | Fusion of the lower abdomen, duplicated fused pelvic bones, external genitalia and anus |
Parapagus | Fused laterally with a common pelvis. Types of parapagus conjoined twins are parapagus dithoracic (separated thoraces), parapagus dicephalus (one trunk two separate heads), and parapagus diprosopus (one trunk, one head and two faces) |
Craniopagus | Fused at the skull with shared meninges. However, brain surface, face and trunk are separate |
Pygopagus | Type of dorsal fusion with shared perineum, sacrococcygeal area and anus. Rectum is separate |
Rachipagus | Type of dorsal fusion involving the dorsolumbar vertebral column and rarely the cervical vertebrae and the occipital bone |