Effect of intrauterine contraceptive device on uterine haemostasis: a morphological study

Menstrual Fluid Factors Mediate Endometrial Repair

Menstruation is a process whereby the outer functionalis layer of the endometrium is shed each month in response to falling progesterone and estrogen levels in a non-conception cycle. Simultaneously with the tissue breakdown, the surface is re-epithelialized, protecting the wound from infection. Once menstruation is complete and estrogen levels start to rise, regeneration progresses throughout the proliferative phase of the cycle, to fully restore endometrial thickness. Endometrial repair is unique compared to tissue repair elsewhere in the adult, in that it is rapid, scar-free and occurs around 400 times during each modern woman's reproductive life. The shedding tissue and that undergoing repair is bathed in menstrual fluid, which contains live cells, cellular debris, fragments of extracellular matrix, activated leukocytes and their products, soluble cellular components and extracellular vesicles. Proteomic and other analyses have revealed some detail of these components. Menstrual fluid, along with a number of individual proteins enhances epithelial cell migration to cover the wound. This is shown in endometrial epithelial and keratinocyte cell culture models, in an ex vivo decellularized skin model and in pig wounds in vivo. Thus, the microenvironment provided by menstrual fluid, is likely responsible for the unique rapid and scar-free repair of this remarkable tissue. Insight gained from analysis of this fluid is likely to be of value not only for treating endometrial bleeding problems but also in providing potential new therapies for poorly repairing wounds such as those seen in the aged and in diabetics.

Haemostatic mechanism in the endometrium: role of cyclo-oxygenase products and coagulation factors

1. The primary mechanism of haemostasis in the endometrium of rat was studied and results were compared to that in the mesenteric artery. 2. The bleeding time of the rat endometrium as assessed by haemoglobin output was significantly decreased after pretreatment of the animals with either indomethacin (5 mg kg-1, i.v.) or meclofenamate (3 mg kg-1, i.v.) whereas the bleeding time was significantly increased in the rat mesenteric artery. 3. The bleeding time of the rat endometrium was unchanged from control values following treatment with prostacyclin (0.5 microgram kg-1 min-1, i.v.) or 1-benzylimidazole (50 mg kg-1, i.v.) whereas the bleeding times were increased in the rat mesentric artery. 4. Administration of heparin (100 units kg-1) increased the bleeding time in the rat mesenteric artery but had no effect on the bleeding time of the endometrium. 5. Superfusion of the endometrium with 16, 16-dimethyl PGE2 (1 microgram ml-1) a vasodilator, increased the bleeding time of the endometrium but superfusion of PGE2 over the mesenteric artery did not affect the bleeding time from this site. 6. Histological studies of the mesenteric artery and the endometrium following haemostatis revealed that the haemostatic plug in the mesenteric artery was mainly composed of platelets and fibrin whereas in the endometrium it was mainly composed of fibrin. 7. These findings suggest that haemostasis in the endometrium may be mediated by the vascular tone and fibrin whereas formation of the platelet plug may be primary mechanism for haemostasis in the mesenteric artery.

Histologic studies on endometrium of menstruating monkeys wearing IUDs: comparative evaluation of drugs

A comparative study was performed to evaluate the effects of antifibrinolytic agents; epsilon-aminocaproic acid (EACA) and tranexamic acid (AMCA); anti-inflammatory drugs (indomethacin, ibuprofen, naproxen); and plant extract (root extract of Boerhaavia diffusa) on the endometrial histology of IUD-fitted menstruating monkeys. A high degree of stromal edema, heavy infiltration of inflammatory cells, long, tortuous endometrial glands, and thin-walled empty blood vessels were observed in IUD endometrium. B. diffusa was found most effective in reducing stromal edema, inflammation, and tortuosity of glands, and in increasing the degree of deposition of fibrin and platelets in the vessel lumen. Antifibrinolytic agents caused partial to complete occlusion of the vessel lumen and anti-inflammatory drugs thickened the vessel wall. Indomethacin reduced inflammation effectively. Conclusively, B. diffusa appears to be a potent antifibrinolytic and anti-inflammatory agent and is, thus, recommended for the treatment of IUD menorrhagia.

Endometrial morphological changes in IUD users: a review

The introduction of an intrauterine device into the uterine cavity induces a foreign body reaction in the surrounding endometrium which is characterized by the infiltration of polymorphonuclear leucocytes and macrophages into the endometrial stroma and subsequently through the surface epithelium. Leucocyte migration is greater with copper IUDs than with inert IUDs. Ulceration of the surface epithelium, haemorrhage of erythrocytes and microthrombosis of stomach capillaries occur in the functional endometrium in contact with inert and copper IUDs. In endometrium adjacent to, but not in contact with, the IUD gaps appear in the endothelial lining of small blood vessels without a haemostatic response. The most striking response in endometrium exposed to progesterone-releasing IUDs is the occurrence of dilated, thin-walled vesicles, associated with a thinning of the surface epithelium and a decidual reaction in the stroma. A uniform suppression of the endometrium in progesterone IUD users is always found after six months of treatment, whereas the insertion of IUDs releasing 20-30 micrograms levonorgestrel induce a profound uniform suppression of the functional endometrium throughout the uterus after only four weeks.

A morphometric study of the effect of oral norethisterone or levonorgestrel on endometrial blood vessels

A morphometric study was undertaken to quantitate vessel numbers in uterine biopsies from a control group of patients, patients with dysfunctional uterine bleeding and patients taking low dose norethisterone or levonorgestrel. Vessels were counted at the endometrial/myometrial junction and in the functional endometrium just below the surface epithelium. The number of arteries at the endometrial/myometrial junction was found to be decreased in patients taking norethisterone and levonorgestrel. An increase was found in the total number of veins and in the number of dilated veins in the functional endometrium of the progestogen-treated specimens. Dilated veins were frequently found close to the endometrial surface and it is possible that they may be the major cause of the irregular bleeding associated with low dose oral progestogens.

Hemostatic mechanisms, independent of platelet aggregation, arrest gastric mucosal bleeding

Platelet adhesion, aggregation, and subsequent plug formation play a major role in the control of cutaneous and vascular hemostasis. Little is known, however, about the hemostatic processes in gastric mucosal tissue. A method for evaluating bleeding from a standard incision in the gastric mucosa of the rat, rabbit, and dog has therefore been developed. By using pharmacological agents that interfere with platelet aggregation and blood coagulation, the mechanism of gastric hemostasis has been compared to that in the vasculature, using the rat mesenteric artery. Intravenous infusion of prostacyclin (0.5 micrograms X kg-1 X min-1), which inhibits platelet aggregation directly, or administration of the thromboxane synthase inhibitor 1-benzylimidazole (50 mg X kg-1) significantly prolonged bleeding in the mesenteric artery yet failed to alter gastric mucosal bleeding. In contrast, a low dose of heparin (100 units X kg-1), which interferes with the clotting process, had no effect on mesenteric bleeding but substantially prolonged bleeding from the gastric mucosa. These findings suggest that, unlike in the skin or vasculature, platelet aggregation plays a minimal role in the initial hemostatic events in the gastric mucosa and that the arrest of gastric hemorrhage is brought about largely by processes primarily involving the coagulation system.

Coagulation factors and fibrinolytic proteins in menstrual fluid collected from normal and menorrhagic women

Menstrual fluid was collected in vaginal cups inserted for 2 h during the first 2 days of menstruation and selected coagulation and fibrinolytic proteins were measured. All the samples showed a virtual absence of thrombin generating activity and exhaustion of fibrinolytic proteins. In 14 women in whom menstrual fluid was collected on both days, no significant difference in the levels of any factor was found apart from alpha-2-macroglobulin which were lower on day 1 than on day 2. Except for plasminogen and alpha-2-macroglobulin concentrations on day 1, no correlation was found between any of the factors on either day and menstrual blood loss (range 15-666 ml).

A functional study of platelets in menstrual fluid

Platelets were isolated from menstrual and peripheral venous blood samples taken from nine women during the first 2 days of menstruation. The washed platelets were tested for their ability to aggregate in response to arachidonic acid, ADP, and collagen, and to metabolize arachidonic acid. Menstrual platelets differed from venous platelets in (1) failing to aggregate when challenged with aggregatory stimuli and (2) producing no appreciable cyclo-oxygenase products from arachidonic acid as reflected in thromboxane B2 release. However, incubation of peripheral venous platelets with menstrual serum obtained from the same patients induced aggregation. The responses of menstrual and peripheral venous platelets were the same irrespective of the patients' total menstrual blood loss. Uterine venous platelets collected during menstruation from two patients at hysterectomy aggregated normally and produced thromboxane B2.

The effects of intrauterine contraceptive devices on the ultrastructure of the endometrium in relation to bleeding complications

The effects of inert (Lippes Loop D and Dalkon Shields) and medicated (copper 7, copper T, and Progestasert) intrauterine contraceptive devices (IUDs) on the ultrastructure of the endometrium were studied in intact human uteri. The most striking morphologic changes induced by the inert and copper-bearing devices were erosion of the surface epithelium and extensive microthrombosis in stromal capillaries of the endometrium in contact with the device. These abnormalities were associated with extravascular thrombi, erythrocytes, and fibrin deposition in the adjacent stroma. Capillary microthrombosis and leukocyte infiltration into the uterine cavity were most extensive around the active part of the copper-bearing devices. With the Progestasert erosion of surface epithelium was rarely seen, but the intact epithelial lining had fewer ciliated cells with flattened and shortened cilia. Large dilated venules were a common finding below the surface epithelium adjacent to the active part of the Progestasert; capillary microthrombosis was found only below the inert arms of the Progestasert. The vascular response of the endometrium to IUDs appears, therefore, to be directly related to the type and proximity of the device. The morphologic changes induced in both surface epithelium and the microvasculature of the endometrium are the likely explanation of the uterine bleeding problems associated with IUDs but are probably intrinsic to the mode of action of the IUD in interfering with implantation.

An ultrastructural study of menstrual blood in normal menstruation and dysfunctional uterine bleeding

Menstrual fluid was obtained from the uterine cavity and vagina in 20 women within the first 48 h of menstruation. Ten of the women had normal menstrual cycles and blood loss and ten were patients with dysfunctional uterine bleeding. The menstrual samples were examined by electron microscopy for the presence of fibrin and platelets and nearly all were found to contain both fibrin and aggregating platelets. By a simple quantitative system no differences in fibrin and platelet content were found between samples collected from the uterine cavity or the vagina. Likewise no difference was found in the morphology of fibrin and platelets between women with normal menstrual loss and patients with dysfunctional uterine bleeding.

Haemostasis in menstrual endometrium in the presence of an intrauterine device

The histology and ultrastructure of the haemostatic response in the endometrium have been studied in 12 uteri containing an inert or copper wound intrauterine contraceptive device (IUCD). The uteri were removed during the premenstrual phase or during the first 96 hours of menstruation. The results have been compared to earlier observations in non-IUCD influenced endometrium. In all uteri the tissue shedding proceeded more slowly in the presence of an IUCD and considerably fewer haemostatic plugs were found. The platelets in these plugs were more loosely packed and less degranulated, and the plugs contained less fibrin than in the absence of an IUCD. Haemostatic plugs were still observed at times when no such plugs were seen in uteri without an IUCD. Unoccluded vessel lesions were regularly seen and vessels open to the shedding surface were occasionally encountered. These observations suggest that IUCD-induced menorrhagia is caused by the combination of delayed shedding and a decreased haemostatic reaction in the endometrium.

Fibrin and platelets in menstrual discharge before and after the insertion of an intrauterine contraceptive device

Eighteen samples of menstrual blood, taken before and after the insertion of an intrauterine contraceptive device (IUD), were collected from the uterine cavity during the first 32 hours of menstruation and studied with light and electron microscopy for the presence of fibrin and platelets. In 12 of the 18 samples extravascular fibrin and platelet aggregates with a high degree of transformation were found. Intravascular thrombi were seen in pieces of tissue in two preinsertion samples. The absence of any intravascular platelets or fibrin was the only consistent difference in postinsertion samples compared to preinsertion samples. This study demonstrates that, contrary to the current belief, clot formation and platelet aggregation do occur in menstrual blood. This process is uninfluenced by the presence of an IUD.

Morphology of haemostasis in menstrual endometrium

Light microscopy, electron microscopy and immunofluorescence were used to study the endometrium from nine uteri removed during the first 72 hours of normal menstruation. During premenstrual spotting, stromal disintegration and vessel lesions without any haemostatic reaction were seen. Up to 20 hours after the onset of menstrual bleeding, blood extravasation was prominent in the functional endometrium. The vessels in this layer were partly or totally sealed by intravascular thrombi functioning as haemostatic plugs. The thrombi contained various amounts of platelets and fibrin and were shed with the tissue. New plugs formed up-stream in the same vessels. Twenty hours after the onset of menstruation, most of the functional endometrium had been desquamated. From 20 to 72 hours after the start of menstrual bleeding no or few thrombi were seen. Haemostasis may then be caused by adherence of vessel lips.