The effect of the progesterone-releasing intrauterine device on uterine endometrium and fallopian tube epithelium.

A scanning and transmission electron microscopy study was undertaken of the effect of the progesterone releasing intrauterine device (Progestasert, Alza Corporation, USA) on the uterine endometrium and fallopian tube epithelium. Small erosions of surface epithelium and microthrombosis of stromal capillaries were found in the endometrium below the inert part of the device. A reduction of ciliated cells and shortened cilia were seen in the endometrium below the active part of the device and large dilated venules were present in the underlying stroma. Fallopian tubes from IUD patients contained fewer ciliated cells than those of the controls. The morphological changes described are likely to be major factors responsible for the irregular bleeding which occurs with Progestasert IUDs and the possible increase in tubal pregnancy.