Effects of a progesterone-releasing intrauterine contraceptive device on endometrial blood vessels: a morphometric study

Angiogenesis in abnormal uterine bleeding: a narrative review

BACKGROUND

Abnormal uterine bleeding (AUB) has a significant socioeconomic impact since it considerably impacts quality of life. Therapeutic options are frequently based on trial and error and do not target disease aetiology. Pathophysiological insight in this disease is required for the development of novel treatment options. If no underlying cause is found for the AUB (e.g. fibroids, adenomyosis, polyps), endometrial-AUB (AUB-E) is usually caused by a primary endometrium disorder. When AUB is induced by prescribed (exogenous) hormones, it is classified as iatrogenic-AUB (AUB-I). Considering vascular modulation and function, AUB-E and AUB-I both could potentially result from abnormal vascularization in the endometrium due to alterations in the process of angiogenesis and vascular maturation.

OBJECTIVE AND RATIONALE

We aim to investigate the fundamental role of angiogenesis and vascular maturation in patients with AUB and hypothesize that aberrant endometrial angiogenesis has an important role in the aetiology of both AUB-E and AUB-I, possibly through different mechanisms.

SEARCH METHODS

A systematic literature search was performed until September 2021 in the Cochrane Library Databases, Embase, PubMed, and Web of Science, with search terms such as angiogenesis and abnormal uterine bleeding. Included studies reported on angiogenesis in the endometrium of premenopausal women with AUB-E or AUB-I. Case reports, letters, reviews, editorial articles, and studies on AUB with causes classified by the International Federation of Gynecology and Obstetrics as myometrial, oncological, or infectious, were excluded. Study quality was assessed by risk of bias, using the Cochrane tool and the Newcastle-Ottawa Scale.

OUTCOMES

Thirty-five out of 2158 articles were included. In patients with AUB-E, vascular endothelial growth factor A and its receptors (1 and 2), as well as the angiopoietin-1:angiopoietin-2 ratio and Tie-1, were significantly increased. Several studies reported on the differential expression of other pro- and antiangiogenic factors in patients with AUB-E, suggesting aberrant vascular maturation and impaired vessel integrity. Overall, endometrial microvessel density (MVD) was comparable in patients with AUB-E and controls. Interestingly, patients with AUB-I showed a higher MVD and higher expression of proangiogenic factors when compared to controls, in particular after short-term hormone exposure. This effect was gradually lost after longer-term exposure, while alterations in vessel maturation were observed after both short- and long-term exposures.

WIDER IMPLICATIONS

AUB-E and AUB-I are most likely associated with aberrant endometrial angiogenesis and impaired vessel maturation. This review supports existing evidence that increased proangiogenic and decreased antiangiogenic factors cause impaired vessel maturation, resulting in more fragile and permeable vessels. This matches our hypothesis and these mechanisms appear to play an important role in the pathophysiology of AUB-E and AUB-I. Exploring the alterations in angiogenesis in these patients could provide treatment targets for AUB.

Utility of the Levonorgestrel-Releasing Intrauterine System in the Treatment of Abnormal Uterine Bleeding and Dysmenorrhea: A Narrative Review

INTRODUCTION

We undertook a literature review of the use of levonorgestrel-releasing intrauterine devices when utilized for heavy menstrual bleeding and/or dysmenorrhea.

METHODS

A narrative review of articles in the Scopus and Medline databases was conducted.

RESULTS

A number of options exist for the management of both abnormal uterine bleeding (AUB) and dysmenorrhea, and evidence is accumulating that the insertion of a levonorgestrel-releasing intrauterine system (LNG-IUS) represents a useful option for their long-term treatment. The idea of using a progestogen released in utero was initially conceived to achieve long-term contraception, but it was quickly found that these systems could be utilized for a number of therapeutic applications. The first device to be made commercially available, Progestasert, was withdrawn from the market because, in the event of contraceptive failure, it caused a disproportionate percentage of extrauterine pregnancies. On the other hand, the LNG-IUS continues to be successfully utilized in its various variants, releasing 20, 13, or 8 μg/day. These devices have a respective duration of action of 7 (possibly 8), 5, and 3 years, and there exist versions of frameless systems affixed to the myometrium of the uterine fundus. In the present review, following a brief description of the major causes of AUB and dysmenorrhea, the molecular bases for the use of the LNG-IUS are summarized. This is followed by a compendium of its use in AUB and dysmenorrhea, concluding that the insertion of the system improves the quality of life, reduces menstrual blood loss better than other medical therapies, and decreases the extent of dysmenorrhea and pelvic pain. In addition, there is no evidence of a significant difference in these outcomes when the use of the LNG-IUS was compared with improvements offered by endometrial ablation or hysterectomy. Possibly, the most important mechanism of action of the system consists of its ability to induce amenorrhea, which effectively eliminates heavy bleeding and dysmenorrhea. However, no method is ideal for every woman, and, in the case of the LNG-IUS, younger age and severe dysmenorrhea seem to be associated with a higher risk of discontinuation.

CONCLUSION

The higher-dose LNG-IUS is a useful tool for HMB and dysmenorrhea in women of all ages. The low cost and ease of use make the LNG-IUS an attractive option, especially when contraception is also desired.

Effects of progestin-only contraceptives on the endometrium

INTRODUCTION

The contraceptive activity of synthetic progestins is mediated through three basic mechanisms: (a) An anti-gonadotrophic action leading to the inhibition of ovulation; (b) Changes in cervical mucus characteristics that inhibit sperm penetration and (c) desynchronization of the endometrial picture necessary for implantation.

AREAS COVERED

Mechanisms involved in the progestin-induced endometrium desynchronization are individually reviewed for each of the routes of administration and, whenever possible, by individual members of the various families of synthetic progestin derivatives.

EXPERT OPINION

For contraceptive purposes, progestins are today administered through several routes: orally, as injections, subdermally and via the vagina or the uterine cavity. Given this variety of modalities, their effects may differ, depending on the route of administration, concentration reached at the level of the endometrium and the duration of use. These are characterized by inactivation of the endometrium. Progestin-only contraception provides a safe and effective control of fertility regulation, although, they are associated with the problem of endometrial break through bleeding that may lead to discontinuation. Unfortunately, in spite of a major research effort over two decades, there is not, as yet, an established long-term intervention available to manage bleeding irregularities, making mandatory a deeper understanding of the mechanisms involved is required.

Long-term progestin contraceptives (LTPOC) induce aberrant angiogenesis, oxidative stress and apoptosis in the guinea pig uterus: A model for abnormal uterine bleeding in humans

Background

Irregular uterine bleeding is the major side effect of, and cause for, discontinuation of long-term progestin-only contraceptives (LTPOCs). The endometria of LTPOC-treated women display abnormally enlarged, fragile blood vessels (BV), decreased endometrial blood flow and oxidative stress. However, obtaining sufficient, good quality tissues have precluded elucidation of the mechanisms underlying these morphological and functional vascular changes.

Methods

The current study assessed the suitability of the guinea pig (GP) as a model for evaluating the uterine effects of LTPOC administration. Thus GPs were treated with a transdermal pellet for 21 days and examined for endometrial histology, angiogenic markers as well as markers of oxidative stress and apoptosis.

Results and Discussion

We now demonstrate that GP uteri were enlarged by both estradiol (E2) and medroxyprogesterone acetate (MPA) (p < 0.001). Effects of MPA on uterine weight differed significantly depending on E2 levels (p < 0.001), where MPA opposed the E2 effect in combined treatments. Angiogenesis parameters were similarly impacted upon: MPA alone increased BV density (p = 0.036) and BV average area (p = 0.002). The presence of E2 significantly decreased these parameters. These changes were associated with highly elevated of the lipid peroxidation product, 8-isoprostane (8-isoP) content in E2+MPA-treated and by nuclear 8-OH-deoxyguanosine (8oxoG) staining compared to all other groups (p < 0.001). Abnormalities in the E2+MPA group were consistent with chromatin redistribution, nuclear pyknosis, karyolysis and increased apoptosis as observed by a marked increase in TUNEL labeling.

Conclusions

LTPOC exposure alters endometrial vascular and tissue morphology consistent with oxidative stress and apoptosis in a complex interplay with endogenous estrogens. These findings are remarkably similar to in vivo change observed in the human uterus following LTPOC administration. Hence, the GP is an excellent model for the study of LTPOC effects on the uterus and will be extremely useful in determining the mechanistic pathways involved in this process which cannot be conducted on humans.

Endometrial vascularization in levonorgestrel intrauterine device users; computerized microvessel measurement study

Levonorgestrel use in the levonorgestrel intrauterine device (LNG-IUS) induces vascular distension within the superficial layer of the endometrium and massive pseudodecidualization. With a computer-assisted image analysis system, we objectively measured the vascular bed in LNG-IUS users and compared it to the physiological endometrium. A study was undertaken on 25 women using LNG-IUS, in an outpatient procedure at the time of removal of the IUS and compared with 11 normally cycling women (control group). Suction curette specimens were obtained just after retrieval of the IUS, and immunohistochemistry was carried out with a specific marker of the endothelial cells (CD31). Number of vessels decreased in the LNG-IUS group to 60/mm2 versus 124/mm2 in the control group, and mean vessel area increased to 1255 microm2 versus 157 microm2, respectively, in the control group. The decrease in mean vascular density and the increase of mean vessel area in the LNG-IUS group, compared to the control group, were both highly significant (p<.001).

Impact of different progestins on endometrial vascularisation of postmenopausal women. A retrospective image analysis—morphometric study

OBJECTIVES

To determine if the vascularisation of the endometrium is dependent on the administered progestin during sequential hormone replacement therapy.

METHODS

Nine women received percutaneous estradiol-17 beta, 1.5 mg/day from days 1 to 24 combined with 200 mg/day micronised progesterone from days 11 to 24 of the treatment cycle. Fifteen women received percutaneous estradiol, 1.5 mg/day from days 1 to 24, combined with 10 mg/day chlormadinone acetate from days 11 to 24. Eleven women received percutaneous estradiol, 50 microg/day from days 1 to 28 combined with percutaneous norethisterone acetate, 0.3mg/day form days 14 to 28. Twelve women received intranasal estradiol, 300 microg/day from days 1 to 25 combined with 0.5 mg of promegestone from days 11 to 24. Eleven spontaneous cycling women had an endometrial biopsy during luteal phase and served as controls. Endometrial biopsies were processed routinely between days 18 and 24 and sections were immunostained using anti-CD34 antibody to identify vascular endothelial cells, which were treated with an automatic image analysis system.

RESULTS

mean (+/-S.D.) vascular density for controls was 147+/-41.5 vessels/mm(2), with mean vessel area of 143+/-60.9 microm(2). In chlormadinone users endometrial microvascular density and mean vessel area did not differ from the control group (150.2+/-58.6 and 152.9+/-70.5). The other three progestins generated a significant increase of mean vessel density, 179.6+/-51.6 with micronised progesterone, 178.5+/-67.6 with norethisterone and 179.6+/-48.4 with promegestone. The mean vessel area was lower in the latter three groups, respectively, 108.4+/-39.0, 97.5+/-46.5 and 141.6+/-66.7 microm(2), promegestone leading to non significant difference with control.

CONCLUSION

regarding vascularisation, chlormadinone and control group gave similar patterns. Promegestone was associated with an increase of the number of vessels, as did micronised progesterone or norethisterone; the mean vascular area was the smallest in the norethisterone group.

Endometrial response to hormone replacement therapy as assessed by expression of insulin-like growth factor-binding protein-1 in the endometrium

OBJECTIVE

To assess endometrial response to parenteral levonorgestrel in hormone replacement therapy by means of morphological criteria and immunohistochemical staining of insulin-like growth factor-binding protein-1 (IGFBP-1).

DESIGN

Endometrial samples were collected from 35 postmenopausal women after 12 to 22 months of continuous combined estrogen-progestin therapy. All subjects were treated with parenteral progestin. A group of 8 women was treated with a subdermal levonorgestrel-releasing implant, and 27 women had a levonorgestrel-releasing intrauterine device (IUD). Sections of formalin-fixed paraffin-embedded biopsies were used for immunohistochemistry and after hematoxylin-eosin staining for routine histologic examination.

RESULTS

Atrophic epithelium with pronounced decidual reaction in the stroma was detected by histologic examination in all endometrial samples obtained from 27 women treated with the levonorgestrel-releasing IUD. In contrast, the endometrium was proliferative in seven of eight (87.5 percent) biopsies obtained from women treated with the levonorgestrel-releasing implant. Immunoreactive IGFBP-1 was detected in decidualized stromal cells in all endometrial samples obtained during intrauterine levonorgestrel therapy, whereas only one of eight samples obtained from women treated with subdermal levonorgestrel exhibited weak staining for IGFBP-1.

CONCLUSIONS

Our data show that both the morphological and biochemical response of post- menopausal endometrium to parenteral levonorgestrel was strikingly different, depending on the route of progestin administration, and that the decidual reaction and epithelial atrophy induced by intrauterine levonorgestrel were associated with expression IGFBP-1 in decidualized stromal cells.

A morphometric study on the endometrial activity of women before and after one year with LNG-IUD in situ

The endometrium was studied by morphometry in 34 healthy women before and after one year's use of an IUD releasing levonorgestrel at a rate 20 micrograms/24 hr (LNG-IUD-20). The effect was compared with that of an IUD releasing 2 micrograms levonorgestrel/24 hr (LNG-IUD-2). The appearance of suppressed endometrial proliferative activity and increased inflammatory reaction was similar in the two experimental groups, suggesting that the morphological alterations were independent of the LNG dosage. The result of this study, combined with clinical data, suggests that LNG-IUD-20 could replace LNG-IUD-2 without any additional side effects. The efficacy of LNG-IUD-20 is also likely to last for a longer period than the LNG-IUD-2.

Endometrial morphometry in users of intrauterine contraceptive devices and women with ovulatory dysfunctional uterine bleeding: a comparison with normal endometrium

Copper-bearing intrauterine contraceptive devices (IUCD) are commonly associated with menorrhagia. They cause certain morphological changes in the endometrium. These have been extensively reported and the mechanisms of menorrhagia have been investigated in a number of studies. By contrast, ovulatory dysfunctional uterine bleeding has not been as widely studied and mechanisms of menorrhagia in these patients are still not well understood. In this study, we examined endometrial morphometry in a group of women using IUCD, a group of women with ovulatory dysfunctional bleeding, and a control group of women with entirely normal cycles. There was increased leukocytic infiltration of the endometrium in both groups of women with menorrhagia compared to control cases. In addition, IUCD use was associated with greater luteal phase glandular epithelial height, supporting the concept of a secretory function defect in glandular epithelium. Possible links are postulated between static morphometric observations and dynamic biochemical changes.

The pathology of intra-uterine contraceptive devices

The IUCD is a simple and effective way of producing contraception without the need for patient compliance. It is not rendered ineffective by other drugs, as may be steroid contraceptives, and its side-effects, for carefully selected patients, are considered by most practitioners to be acceptably low (Van Kets et al. 1989).

Observation of the activity of factor VIII in the endometrium of women pre- and post-insertion of three types of IUDs

The endometrial materials were obtained from 90 women who had been randomly inserted with three types of IUDs (Stainless steel ring, SS; copper T 220, TCu 220, and levonorgestrel-releasing device, LNG). An immunoperoxidase reaction, PAP method, with the antiserum of Factor VIII as the primary antibody, was carried out to detect the Factor VIII activity in the endometrial endothelium pre- (control) and post-insertion of the IUDs. The results revealed that: 1. There was a generalized lower Factor VIII activity in the endometrium of women post-insertion of IUDs (except LNG). 2. Comparison of the Factor VIII activity in the endometrium of women using different types of IUDs showed that the TCu type and the SS type decreased the activity significantly whereas the activity remained unchanged after 3-6 months' use of the LNG-IUD. The different types of IUDs seemed to influence the coagulation regulatory system in different ways; the lower Factor VIII activity, the more tendency to bleeding. 3. The Factor VIII activity in the endometrium of women using IUDs was lower in all phases of the menstrual cycle including the proliferative phase when the Factor VIII activity is normally high. It cannot be excluded that this could be a contributing factor to IUD-induced bleedings.

Endometrial vascular features prior to and following exposure to levonorgestrel

A study of endometrial vasculature, mast cell numbers and tissue levels of tissue plasminogen activator (tPA) prior to and following exposure to levonorgestrel (20 micrograms/day) administered via a vaginal ring was undertaken. Following exposure to levonorgestrel, significantly fewer arterioles were present in the endometrium. During the early secretory phase of the control cycle, a positive correlation was found between mast cell numbers and progesterone levels. Levonorgestrel-exposed biopsies had significantly higher numbers of vessels with endothelial gaps and haemostatic plugs when compared with early secretory endometrium and significantly higher numbers of haemostatic plugs when compared with mid-late secretory endometrium. During the early secretory phase, the numbers of vessels possessing haemostatic plugs positively correlated with the peripheral blood levels of oestradiol and the number of contracted endothelial cells showed a positive correlation with progesterone levels. In mid-late secretory biopsies, the numbers of vessels with contracted endothelial cells were found to correlate negatively with oestradiol levels and the difference in the levels of contracted endothelial cells between the mid-late secretory endometrium and levonorgestrel-exposed endometrium correlated positively with progesterone levels of post-treatment cycles.

Ultrastructural comparative study on endometrium of Chinese women using intrauterine devices of stainless steel ring, copper T220, and releasing levonorgestrel: morphometry of microvessels

An electron microscopic morphometric study was performed for three kinds of IUDs, the stainless steel ring (SS), the copper T220 (TCu) and the WHO levonorgestrel IUD (LNG), for comparison of their effects on microvessels of the endometrium of women wearing the devices. The morphometry of plasmolemmal vesicles (PV) of the endothelial cell as well as the contracted and degenerated endothelial cell were undertaken. The results showed that all three IUDs led to significant changes in blood vessels, i.e., a higher percentage of contracted and degenerated cells than in the control group (p less than 0.01), and an increase in PV after insertion of the devices (p less than 0.01). The TCu caused more contracted endothelial cells than the SS (p less than 0.01) and the LNG (p less than 0.05). The levonorgestrel-releasing IUD resulted in a higher increase of PV than the SS and the TCu. For the differences between bleeding and non-bleeding groups, only the TCu showed a higher percentage of contracted cells (p less than 0.05).

The effect of intrauterine devices, the stainless steel ring, the copper T220, and releasing levonorgestrel, on the bleeding profile and the morphological structure of the human endometrium--a comparative study of three IUDs. A morphometric study of 96 cases

Thirty-four women using the stainless steel ring (SS), 43 women using the Copper T220 (TCu), and 19 women using levonorgestrel-releasing intrauterine devices (LNG) were admitted to the study. The light microscopic biopsy material was subjected to morphometric studies including 8 indices of endometrial activity before (Control) and after 24 months of exposure to the SS and TCu device and 3-10 months of exposure to the LNG device. The women were grouped into subjects with and without intermenstrual and prolonged bleeding. The results revealed that there were highly significant differences between the IUDs at the endometrial level as displayed by morphometry. However, the difference between bleeders and non-bleeders was not significant in any of the three types of IUDs. Although the mode of action of these IUDs at the endometrial level is different, the mechanism responsible for the irregular endometrial bleeding needs to be further investigated.

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.

Mechanism of action of intrauterine devices: biochemical changes

The mechanism of action of intrauterine devices varies from one type of device to another, although the principle of action is the same, namely, to interfere with the physiology of reproduction at the endometrial level. The biochemical changes of the endometrial tissue and the composition of the uterine fluid have been reviewed in relation to the use of inert, copper-medicated and steroid-releasing IUDs. All IUDs, whether inert or medicated, provoke a significant increase in the number of neutrophils, mononuclear cells and plasma cells, the presence of which is unrelated to the tissue infiltration of inflammatory cells occurring pre-menstrually of the normal menstrual cycle. The increase of leucocytes in IUD-users is compatible with a foreign body reaction which may be related to the antifertility effect. The addition of copper to an inert IUD has been shown to significantly alter the metabolism of the endometrial cells, e.g. the enzymatic activity and the DOVA-synthesis. The steroid-medicated IUDs represent a new approach to intrauterine contraception where the morphology of the endometrium is considerably altered, showing massive decidual changes, atrophic glands and sometimes atrophy of the whole functional layer. In addition, there is an important foreign body reaction, similar to that of the inert IUDs. The enzymatic activity, as well as the proliferative activity was significantly altered in the endometrium of these IUD-users. Changes in the endometrial fibrinolytic activity in IUD-users have been demonstrated to be related to the presence of irregular bleeding. Micro-traumata of the endometrium and the increased fibrinolytic activity may also interfere with the protective processes present in the physiologically normal endometrium. Further studies on the factors influencing the fertilizing ability of the spermatozoa in the female genital tract, as well as on the conditions of the human endometrium required for the implantation of a blastocyst, may yield important information for the improvement of intrauterine contraception.

Treatment of increased menstrual blood loss in IUD users

Although bleeding problems represent the commonest side effect of IUDs and an important medical reason for discontinuation of use, its pathogenesis still remains incompletely understood and a standard universally acceptable therapy is not yet available. Proper insertion, change in size, material or shape of the IUD, as well as custom fitting to avoid dimensional incompatibilities, did not significantly improve the IUD-associated bleeding problems. Addition of copper to inert devices seemed to slightly improve the bleeding by reducing the antifibrinolytic activity but probably more was achieved through reducing the device size. Hormone-releasing devices appear to reduce the amount of bleeding significantly but a post-insertion phase of irregular spotting is a common complaint. Locally released antifibrinolytic agents were tried in limited investigations but a short period of drug release restricted further evaluation. Systemic administration of antifibrinolytic agents and non-steroidal anti-inflammatory drugs hold promise for the control of IUD-induced menorrhagia. The duration of bleeding and intermenstrual spotting still remains an unresolved clinical problem that requires further evaluation. This area of clinical concern in IUD use needs more in depth understanding and testing of new agents, particularly in the area of local release of antihemorrhagic agents.

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.

Quantitative uterine histology during the menstrual cycle in relation to measured menstrual blood loss

Endometrium and myometrium were collected at hysterectomy from 42 women with measured menstrual blood loss (range 4-840 ml). The specimens, obtained throughout the menstrual cycle, showed no evidence of organic disease on histological examination. The volume fraction occupied by arteries at the myometrial-endometrial junction, and by glandular tissue throughout the endometrium was estimated with a point counting technique. The index of volume-to-surface ratio of endometrial glandular tissue was examined by a combination of point counting and linear intercept methods. No correlation was found between menstrual blood loss and endometrial and myometrial arterial density, endometrial glandular density and volume-to-surface ratio. Consequently, menorrhagia, occurring in the absence of obvious pathology, does not appear to result from an excessive number of arteries of from abnormal glandular distribution.