The morphologic changes of endometrial spiral arterioles in IUD-induced menorrhagia.

To investigate the relationship between IUD-induced menorrhagia and spiral arteriolar function, we examined the endometrium under light and electron microscope on samples obtained within 24 hours after the onset of premenstrual spotting. These samples included an IUD bleeding group (20 cases), an IUD non-bleeding group (20 cases) and an IUD non-user group (10 cases) as controls. Compared with the IUD non-user group the degenerative changes of spiral arteriolar wall were more severe and dilation of the spiral arteriolar lumen was more obvious, especially in the spongeous layer. In the IUD non-user group these changes were mild, suggesting that IUD-induced menorrhagia might be correlated with poor contractility of spiral arterioles in the spongeous layer.