[Detection of the intermediate trophoblast as evidence of intrauterine pregnancy].

With spontaneous abortion the conceptus is often expelled and lost right at the beginning, and uterine curettings then contain only endometrial fragments and clotted blood. Even complete embedding of all available material for histologic examination will not reveal any chorionic villi, and ectopic pregnancy can thus not be excluded. In such cases, the intermediate trophoblast can sometimes still be demonstrated within the endometrial tissue. This highly invasive trophoblast is difficult to identify using conventional staining, but cytokeratin antibodies are reliable markers of this cell type. Using immunohistochemistry, these fetal components could be demonstrated in 27 of 95 specimens (28.5%), proving the intrauterine nature of the aborted pregnancy. In some cases the fetal derivation of intermediate trophoblast was demonstrated by using in situ hybridisation to mark repetitive sequences on the Y-chromosome in the interphase nucleus.