Effects of intrauterine devices on nuclear deoxyribonucleic acid metabolism in rabbit blastocysts: an autoradiographic study.

A metabolic parameter, DNA synthesis, was measured in rabbit blastocysts exposed to Silastic intrauterine devices (IUDs) and compared with those without IUD exposure. Autoradiographic detection of 3H-thymidine uptake showed that the IUD-exposed blastocysts contained fewer labeled cells than their IUD-free equivalents. The depressed DNA synthesis may be caused by either a block in the cell cycle or a block in DNA synthesis itself. Either way, the result could be consistent with the observation that embryo deaths occur at all growth stages, preimplantation, during implantation, and postimplantation.

Ultrastructural hemostasis in response to vascular injury induced by intrauterine devices in human endometrium.

PIP: 8 micrographs are presented to help elucidate the mechanism of endometrial bleeding caused by IUDs. A previous study, which reported endometrial vessels with defects or gaps in the superficial portion of IUD-exposed endometrium, is expanded. Since the endothelial cells forming these gaps were in stages of degeneration to complete necrosis, perhaps IUD/endometrial interactions injured some of the superficial vessels which then degenerated, formed gaps, and allowed blood to escape. However, the same endothelial degeneration should initiate platelet adhesion, aggregation, and thrombosis. Yet the micrographs showed degenerated endothelial cells at the vessel gaps, gaps which represent disintegrated endothelial cells, and collagen which appeared to be directly exposed to luminal blood through the gaps. All of these hemostasis-initiating conditions resulted in a surprizing low level of activity. Rarity of platelet and/or fibrin thrombi plugging vessel gaps in IUD-exposed endometrium supported the feasibility of bleeding through small gaps. The interstitial hemorrhage is apparent by electron micrograph. When the concentration of red cells within the superficial endometrium became sufficiently high, apparently the erythrocytes either exuded through the spaces between surface epithelial cells or ruptured into the uterine caivty and resulted in clinical bleeding.^ieng

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.

Vessel density in endometrium of women with and without intrauterine contraceptive devices: a morphometric evaluation.

Increased vascularity was found in the endometrial functionalis in uteri of women wearing intrauterine contraceptive devices (IUDs) as compared to uteri of women without IUDs (control subjects). Vessel concentration was highest in endometrial tissue adjacent to that tissue which was depressed by the IUD. In control tissues there was a significant variation in vascularity according to geographic location in the following order of magnitude: fundus greater than corpus greater than cornua greater than isthmus. No significant variation was found, however, among different phases of the ovarian cycle in either control or IUD cases. Increased endometrial vascularity could be a reaction to vessel damage caused by the IUD and for several reasons may contribute to IUD-induced endometrial bleeding.