Histological study of the materno-embryonic interface in spontaneous abortion.

In a histological study of 184 specimens of complete spontaneous abortion, the following points were delineated. In cases of anomaly or death of the conceptus, there was a reduced trophoblastic penetration into the decidua and into the spiral arteries where physiological changes were limited or absent. Trophoblastic proliferation within the columns and the outer shell was limited with frequent disruption or even disappearance of the shell. These findings seem to be related to the untimely initiation of blood flow in the intervillous space which in turn is associated with arrest of pregnancy and eventual expulsion.