Ultrastructural alterations in human endometrium caused by intrauterine contraceptive devices

Biopsies of endometrium from women using intrauterine contraceptive devices (IUDs) were examined by electron microscopy to elucidate the possible cause of IUD-associated uterine hemorrhage. The findings reveal the presence of degenerated, shrunken cells in the endometrial glands of IUD users. These cells, termed pyknotic or apoptotic, are more prevalent in tissue from women with complaints of excessive bleeding than in cases without such complaints. The pyknotic cells often show discontinuities of the plasma membrane at their luminal pole, from which cell contents stream into the lumen. Sometimes erythrocytes are also observed in the lumen. A second alteration in the ultrastructure of the endometrium is an abnormal increase in microfilaments in the epithelial cells. These two changes, a large number of pyknotic cells on the one hand and increase in microfilaments on the other, are correlated with excessive bleeding but they do not explain in simple terms of outflow of erythrocytes. Probably some inflammatory mechanism is involved. The increased number of microfilaments might be helping the movement of fluid from healthy to pyknotic cells.