Pathological consequences of the vanishing twin.

Fetus papyraceus is a mummified, compressed fetus occurring in association with a viable twin. The death of the fetus usually occurs early in the second trimester. A co-twin dying earlier may be absorbed completely, whilst later fetal death usually results in macerated, but not compressed fetuses. This course of events can be well demonstrated by ultrasonography. The death of one fetuses may be associated with minor malformations of the surviving one. After termination of twin pregnancies the detailed check-up of the newborn and histopathological examination of the placenta is essential.