[Value of histologic examination of the interamniotic membrane in the twin placenta for confirmation of chorionicity diagnosis].

The interest of twin chorionocity and zygosity diagnosis is unquestioned. Indeed, in many medical situations, the knowledge of zygosity is an important fact for management of twins. Prenatal echographia is not a perfect tool to characterize chorionicity, and so postnatal examination of the placenta is always necessary.