allantoidoangiopagus

om·pha·lo·an·gi·op·a·gus

(om'fă-lō-an'jē-op'ă-gŭs),
Unequal conjoined twins in which the parasite derives its blood supply from the placenta of the autosite. See: conjoined twins.
[omphalo- + G. angeion, vessel, + pagos, something fixed]

al·lan·toid·o·an·gi·op·a·gous twins

unequal monochorial twins with fusion of their allantoic vessels within the placenta; the lesser twin is essentially a parasite on the placental circulation of the larger twin.

allantoidoangiopagus

[al′əntoi′dō·an′jē·op′əgəs]
Etymology: Gk, allantoeides, sausagelike, angeion, vessel, pagos, fixed
conjoined monozygotic twin fetuses of unequal size that are united by the vessels of the umbilical cord. Also called omphaloangiopagus. See also omphalosite. allantoidoangiopagous, adj.