Twins, Conjoined

**Definition:** MONOZYGOTIC TWINS who are joined in utero. They may be well developed and share only a superficial connection, often in the frontal, transverse or sagittal body plane, or they may share a partial duplication of a body structure. Alternatively, there may be a small and incompletely developed twin conjoined to a larger, more fully developed twin.

**Tree numbers:** - C16.131.085.806

**Synonyms:** - Siamese Twins - Twins, Siamese