Morphologic studies on IUD-induced metrorrhagia. I. Endometrial changes and clinical correlations

Morphologic studies on human hysterectomy specimens indicate the IUD elicits a vascular reaction which is most pronounced in the endometrium adjacent to the device. This reaction includes increased vascularity, congestion and increased permeability, and degeneration with defect formation. In addition, there is poor hemostatic responsiveness to vascular permeability and damage. The reaction leads to interstitial hemorrhage which undoubtedly causes metrorrhagia. A likely cause for initial vascular damage is mechanical stress transmitted by the IUD through the endometrium to its vascular network. Vascular reaction and poor hemostatic responsiveness may be perpetuated during each cycle by the products released from endothelial cell degeneration and necrosis. Bleeding is one of the most frequent complications leading to discontinuation of an otherwise effective form of long-term contraception and family spacing. Therefore, its solution could be of crucial importance to world-wide population control. Our findings suggest that better understanding of the mechanism of IUD-induced metrorrhagia should result from closer study of the endometrium adjacent to that which is compressed by the IUD.