Placental changes as a consequence of the interruption of midtrimester pregnancies by prostaglandin F(2alpha). A study of 23 cases

Placentae from 23 patients whose midtrimester therapeutic abortions were induced by the prostaglandin (PG) F(2alpha) were examined microscopically. In a majority of the cases, the predominant finding was severe decidual necrosis. Different quantities of edematous villi, with or without congestion, containing swollen stromal Hofbauer cells, were found along with trophoblastic necrosis and subchorionic intervillous thrombosis. The amniotic epithelium, however, had usually not degenerated in spite of the intraamniotic injection of PGF(2alpha). These findings were compared with the histological findings described in placentae from 18 cases of midtrimester spontaneous abortion with normal fetuses. It seems that prostaglandins used in midtrimester abortion affect the placental membranes to a lesser degree than do hypertonic solutions. These findings might explain the fewer maternal complications in PGF(2alpha) midtrimester abortions. The significance of decidual changes and their role in the production of maternal complications is unknown.