Conjoined Twins

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Types of Conjoined Twins

Conjoined twins are usually classified by the point at which they are joined (the Greek word pagos, meaning “that which is fixed.”) Here are some of the main types:

Craniopagus

Head-to-head, about 2% of all conjoined twins.

  Pyopagus

Pelvis-to-pelvis, about 19% of all conjoined twins.

      Parapagus (sometimes called Diprosopus)

Lateral union of the trunk, about 5% of all conjoined twins. Heart sometimes involved.

  Cephalothoracopagus

Fusion of head and thorax.

 

  Thoracopagus

Chest-to-chest, the most common form of conjoined twins (about 35%).

The heart is usually shared and there are associated vascular abnormalities, complicating surgical separation

 

 

Adapted from: Carlson, B.M. (1994) Human embryology and developmental biology. St. Louis: Mosby-Year Book, Inc., p 43.

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