Menstruation as the pelvic aggressor

Is retrograde menstruation a universal, recurrent, physiological phenomenon? A systematic review of the evidence in humans and non-human primates

STUDY QUESTION

What are the quantitative, qualitative, and temporal patterns of retrograde mentruation?

SUMMARY ANSWER

The extreme quantitative and qualitative heterogeneity of the available studies prevents the definitive conclusion that retrograde menstruation is a universal and consistent phenomenon during the reproductive period.

WHAT IS KNOWN ALREADY

Retrograde menstruation has been defined as a universal, physiological phenomenon that occurs similarly in about 90% of menstruators during the reproductive period. However, uncertainties still exist in terms of the event frequency, total amount, and cellular composition of retrograde menstruation and the differences between individuals with versus those without endometriosis.

STUDY DESIGN SIZE DURATION

Two systematic reviews were performed, one for human studies, and one for non-human primate studies. We retrieved studies from the PubMed and Embase databases published between 1 January 1980 and 1 November 2023. Studies published in the English language were included and identified using a combination of MeSH terms. References from relevant publications were systematically screened and further articles were identified using PubMed's 'similar articles' and 'cited by' functions.

PARTICIPANTS/MATERIALS SETTING METHODS

Results were reported in accordance with the PRISMA guidelines. Studies that did not report original data or provided a review of the field were excluded. Bias analysis was completed for each included human study by using the Newcastle-Ottawa scoring system.

MAIN RESULTS AND THE ROLE OF CHANCE

Fifteen studies were finally included in the human systematic review, mostly with limited sample sizes. The macroscopic visualization of blood in PF during menses was reported with a frequency ranging from 9% to 100%. A prevalence of endometrial cells detected in peritoneal fluid ranging from 8% to 75% was reported in the various studies. Controversial findings were reported in relation to patients with endometriosis. Retrograde menstruation has been evaluated cross-sectionally on single occasions, and no information is available on the course of the phenomenon within an entire cycle and between subsequent cycles. Two studies were included in the non-human primate systematic review; one of them showed that retrograde menstruation was observed more frequently in baboons with naturally occurring endometriosis (83%) than in those with a normal pelvis (51%).

LIMITATIONS REASONS FOR CAUTION

In humans, peritoneal fluid has often been collected at different cycle phases and not systematically during menstruation. The indication for laparoscopy was not always clear for all participants. A wide variety of methods were used to detect endometrial cells, including cytological staining, cell block analysis, immunocytochemistry, and various methods of cell culture.

WIDER IMPLICATION OF THE FINDINGS

The idea that almost all women experience retrograde menstruation regularly and similarly during their reproductive life is currently unsubstantiated. It is an academic notion accepted uncritically. Development of endometriosis may derive from differences in the frequency or severity of the event.

STUDY FUNDING/COMPETING INTERESTS

The review was partially funded by Italian Ministry of Health-Current Research IRCCS. P.Vi. serves as co-editor in Chief of Journal of Endometriosis and Uterine Disorders. E.S. serves as Editor in Chief of Human Reproduction Open and discloses research grants from Ferring, Ibsa, Gedeon Richter, and Theramex, and honoraria from Ibsa and Gedeon Richter. P.Ve. serves as Associate Editor for Human Reproduction Open; is a member of the Editorial Board of the Journal of Obstetrics and Gynaecology Canada, of the Italian Journal of Obstetrics and Gynaecology, and of the International Editorial Board of Acta Obstetricia et Gynecologica Scandinavica; has received royalties from Wolters Kluwer for chapters on endometriosis management in the clinical decision support resource UpToDate; and maintains both a public and private gynecological practice. All other authors declare they have no conflict of interest.

REGISTRATION NUMBER

N/A.

Potential anatomical determinants of retrograde menstruation: a comprehensive narrative review

A century ago, Sampson identified three uterine anatomical structures that may determine the amount of retrograde menstruation and the likelihood of the development of endometriosis: the cervix, the intramural portion of the fallopian tubes, and the myometrium. Critical appraisal was undertaken of data published over the last 40 years on the potential effect of the characteristics of these three anatomical variables on the risk of endometriosis. There is some evidence to support the pathogenic role of the diameter of the cervical canal, stenosis of internal or external orifices, and stiffness of cervical tissue. One study showed a significant association between the morphology of the intramural tubal tract and the frequency of endometriosis. A large body of evidence points to abnormalities of the myometrial structure as the anatomical aberration most consistently associated with endometriosis. These abnormalities have largely been interpreted as signs of early-onset adenomyosis, which may precede endometriosis and even lead to its development by increasing the amount of retrograde menstruation. Future research should aim to verify whether a positive relationship exists between the substantially increased number of ovulatory menses occurring in the decade following menarche, the development of anatomical myometrial abnormalities, changes in the amount of retrograde menstruation over time, and the risk of endometriosis.

Proposal for targeted, neo-evolutionary-oriented, secondary prevention of early-onset endometriosis and adenomyosis. Part I: pathogenic aspects

The potential for repeated ovulation and menstruation is thought to have provided a Darwinian advantage during the Palaeolithic. Reproductive conditions remained relatively stable until the pre-industrial era, characterized by late menarche, very young age at first birth, multiple pregnancies, and prolonged periods of lactational amenorrhoea. For hundreds of thousands of years, menstruators experienced few ovulatory cycles, even though they were genetically adapted to ovulate and menstruate every month. In the post-industrial era, the age at menarche gradually declined, the age at first birth progressively increased, and breastfeeding became optional and often of short duration. This created a mismatch between genetic adaptation and socio-environmental evolution, so that what was initially a probable reproductive advantage subsequently contributed to increased susceptibility to diseases associated with lifetime oestrogen exposure, such as ovarian, endometrial and breast cancer and, hypothetically, also those associated with the number of ovulatory menstruations, such as endometriosis and adenomyosis. The incidence of endometriosis shows a steep and progressive increase around the age of 25 years, but given the consistently reported delay in diagnosis, the actual incidence curve should be shifted to the left, supporting the possibility that the disease has its roots in adolescence. This raises the question of whether, from an evolutionary point of view, anovulation and amenorrhoea should not still be considered the physiological state, especially in the postmenarchal period. However, an increase in the frequency of endometriosis in recent decades has not been demonstrated, although this deserves further epidemiological investigation. In addition, as endometriosis occurs in a minority of individuals exposed to retrograde menstruation, other important pathogenic factors should be scrutinised. Research should be resumed to explore in more detail the transtubal reflux of not only blood, but also endometrial cells, and whether they are systematically present in the peritoneal fluid after menstruation. If repetitive ovulatory menstruation during the early reproductive years is shown to increase the risk of endometriosis and adenomyosis development and progression in susceptible individuals, hormonal interventions could be used as secondary prevention in symptomatic adolescents.

Progestagens and anti-progestagens for pain associated with endometriosis

BACKGROUND

Endometriosis is a chronic inflammatory condition defined by the presence of glands and stroma outside the uterine cavity. It occurs in 7% to 10% of all women of reproductive age and may present as pain or infertility. The pelvic pain may be in the form of dysmenorrhoea, dyspareunia or pelvic pain. Initially a combination of estrogens and progestagens was used to create a pseudopregnancy and alleviate the symptoms associated with endometriosis. Progestagens alone or anti-progestagens have been considered as alternatives because they are inexpensive and may have a better side effect profile than other choices.

OBJECTIVES

To determine the effectiveness of both the progestagens and anti-progestagens in the treatment of painful symptoms ascribed to the diagnosis of endometriosis.

SEARCH METHODS

We used the search strategy of the Menstrual Disorders and Subfertility Group to identify all publications which described or might have described randomised controlled trials (RCTs) of any progestagen or any anti-progestagen in the treatment of symptomatic endometriosis. We updated the review in 2011.

SELECTION CRITERIA

We considered only RCTs which compared the use of progestagens and anti-progestagens with other interventions, placebo or no treatment for the alleviation of symptomatic endometriosis.

DATA COLLECTION AND ANALYSIS

We have added six new studies, bringing the total of included studies to 13 in the update of this review. The six newly included studies evaluated progestagens (comparisons with placebo, danazol, oral or subdermal contraceptive, oral contraceptive pill and danazol, gonadotrophin-releasing hormone (GnRH) analogue and other drugs). The remaining studies compared the anti-progestagen gestrinone with danazol, GnRH analogues or itself.

MAIN RESULTS

The progestagen medroxyprogesterone acetate (100 mg daily) appeared to be more effective at reducing all symptoms up to 12 months of follow-up (MD -0.70, 95% CI -8.61 to -5.39; P < 0.00001) compared with placebo. There was evidence of significantly more cases of acne (six versus one) and oedema (11 versus one) in the medroxyprogesterone acetate group compared with placebo. There was no evidence of a difference in objective efficacy between dydrogesterone and placebo.There was no evidence of a benefit with depot administration of progestagens versus other treatments (low dose oral contraceptive or leuprolide acetate) for reduced symptoms. The depot progestagen group experienced significantly more adverse effects.There was no overall evidence of a benefit of oral progestagens over other medical treatment at six months of follow-up for self-reported efficacy. Amenorrhoea and bleeding were more frequently reported in the progestagen group compared with other treatment groups.There was no evidence of a benefit of anti-progestagens (gestrinone) compared with danazol. GnRH analogue (leuprorelin) was found to significantly improve dysmenorrhoea compared with gestrinone (MD 0.82, 95% CI 0.15 to 1.49; P = 0.02) although it was also associated with increased hot flushes (OR 0.20, 95% CI 0.06 to -0.63; P = 0.006).

AUTHORS' CONCLUSIONS

There is only limited evidence to support the use of progestagens and anti-progestagens for pain associated with endometriosis.

Iron storage is significantly increased in peritoneal macrophages of endometriosis patients and correlates with iron overload in peritoneal fluid

OBJECTIVE

To further investigate peritoneal iron disruption in endometriosis by studying iron storage in peritoneal macrophages of patients with endometriosis compared with controls.

DESIGN

Cross-sectional study.

SETTING

Academic gynecology research unit in a university hospital.

PATIENT(S)

Fifty patients undergoing laparoscopy.

INTERVENTION(S)

Collection of peritoneal fluid samples (N = 50) from patients with (n = 27) and without (n = 23) endometriosis undergoing laparoscopy.

MAIN OUTCOME MEASURE(S)

Quantification of peritoneal macrophage ferritin by immunocytochemical staining and immunodensitometry and measurement of peritoneal iron, transferrin, ferritin, and prohepcidin concentrations.

RESULT(S)

The optical density of peritoneal macrophage ferritin staining was statistically significantly higher in endometriosis patients than in controls. Higher iron concentrations, transferrin saturations, and ferritin concentrations were also detected in case of endometriosis. A statistically significant positive correlation was found between the optical density of macrophage ferritin staining and peritoneal iron concentrations in endometriosis and control patients.

CONCLUSION(S)

Iron storage is statistically significantly increased in peritoneal macrophages of patients with endometriosis and correlates with iron overload in peritoneal fluid. The potential implications of iron accumulation in peritoneal macrophages in case of endometriosis are discussed.

Iron overload in the peritoneal cavity of women with pelvic endometriosis

OBJECTIVE

To examine the possible involvement of iron in the physiopathology of endometriosis.

DESIGN

Prospective study.

SETTING

Department of gynecology in a university hospital.

PATIENT(S)

Seventy patients undergoing laparoscopy.

INTERVENTION(S)

Collection of peritoneal fluid (n = 57), blood samples, and biopsy samples from endometrium (n = 62) and from endometriotic (n = 33) and normal-appearing peritoneum (n = 53).

MAIN OUTCOME MEASURE(S)

Measurement of iron and ferritin in serum and peritoneal fluid and staining of iron deposits with Prussian blue in tissues.

RESULT(S)

Iron and ferritin concentrations were significantly higher in the peritoneal fluid of patients with endometriosis compared with controls during the secretory phase. Higher rates of ferritin and hemosiderin deposits were observed in the peritoneum adjacent to red (100%), black (57%), and white (62%) lesions compared with normal-appearing peritoneum (25%). Deposits were more frequent during the secretory phase than the proliferative phase in healthy peritoneum from controls, whereas they were found throughout the cycle in the vicinity of lesions in patients with endometriosis. Similar rates of iron deposition were observed in the stroma of black and white lesions and in eutopic endometrium from patients with endometriosis.

CONCLUSION(S)

Iron overload was observed in the cellular and peritoneal fluid compartments of the peritoneal cavity of women with endometriosis. Iron deposits seem to be related to the presence of lesions, suggesting that iron may be involved in the pathogenesis of endometriosis.

Macrophages, oxidation, and endometriosis

Retrograde menstruation has been suggested to be the cause for the presence of endometrial cells in the peritoneal cavity. However, little is known about the events that lead to the adhesion and growth of these cells that ultimately result in endometriosis, considering the fact that the disease occurs only in certain women despite the common occurrence of retrograde menstruation in most women. We postulate that, in normal women, the endometrial cells and tissue that arrive in the peritoneal cavity during menstruation are effectively removed by macrophages that are chemoattracted and become resident tissue macrophages in the peritoneal cavity. In contrast, the peritoneal macrophages in women with endometriosis are nonadherent and ineffectively scavenged, resulting in the sustained presence and growth of the endometrial cells. We also postulate that the peritoneal fluid is not a passive reservoir of the factors secreted by cells of the peritoneum, but actively promotes endometriosis. The peritoneal fluid is rich in lipoproteins, particularly low-density lipoprotein, which generates oxidized lipid components in a macrophage-rich inflammatory milieu. The oxidants exacerbate the growth of endometriosis by inducing chemoattractants such as MCP-1 and endometrial cell growth-promoting activity. We provide evidence for the presence of oxidative milieu in the peritoneal cavity of women with endometriosis, the nonscavenging properties of macrophages that are nonadherent, and the synergistic interaction between macrophages, oxidative stress, and the endometrial cells. For example, the peritoneal fluid lipoproteins of subjects with endometriosis have increased the propensity to undergo oxidation as compared with plasma lipoproteins, and the subjects also have increased titer of autoantibodies to oxidatively modified proteins. If the oxidative proinflammatory nature of the peritoneal fluid is an important mediator of endometriosis growth, anti-inflammatory agents and antioxidants might afford protection against endometriosis.

Modern combined oral contraceptives for pain associated with endometriosis

BACKGROUND

Endometriosis is a major women's health-care problem. It causes pain and/or infertility, and affects millions of women worldwide. Endometriosis is defined according to histological criteria by the presence of tissue resembling endometrium in sites outside the uterus, most commonly the ovaries and peritoneum. The aim of treatment has been to remove the deposits of ectopic endometrium that are thought to be responsible for the symptoms of endometriosis. This can be achieved surgically by destroying or removing the implants; medical therapies induce atrophy within the hormonally-dependent ectopic endometrium. The duration of hormonal treatment may be limited by unwanted side effects. There is some evidence, however, from epidemiological research that current use of the combined oral contraceptive pill (OCP) is associated with a reduced incidence of endometriosis. The combined pill has the great advantage over other hormonal treatments that it can be taken indefinitely.

OBJECTIVES

The aim of this review was to establish the role of modern oral contraceptives in the management of painful symptoms ascribed to endometriosis.

SEARCH STRATEGY

The search strategy of the Menstrual Disorders Group was utilised to identify all randomised trials of the use of oral contraceptives in the treatment of symptomatic endometriosis. In addition a search of the Cochrane Controlled Trials Register was undertaken together with approaches to pharmaceutical companies.

SELECTION CRITERIA

All truly randomised controlled trials of the use of oral contraceptive pills in the treatment of women of reproductive age with symptoms ascribed to the diagnosis of endometriosis made visually at a surgical procedure, were included.

DATA COLLECTION AND ANALYSIS

Study quality assessment and data extraction was carried out independently by two reviewers. One of the assessors was an expert in the content matter.

MAIN RESULTS

Only one study was identified which satisfied the inclusion criteria. The oral contraceptive used in a conventional manner was less effective than a GnRH analogue in the relief of dysmenorrhoea. No significant difference was noted between the effectiveness of the oral contraceptive pill and a GnRH analogue in the relief of dyspareunia or non-menstrual pain. Headaches and weight gain were more commonly associated with oral contraceptive usage than with GnRH analogue usage whereas hot flushes, insomnia and vaginal dryness were less common.

REVIEWER'S CONCLUSIONS

There is a paucity of data relating to the use of oral contraceptive preparations in the treatment of symptomtic endometriosis. The data such as it is supports the common practice of the use of the oral contraceptive pill as a first line therapy but further research is required to fully evaluate its role in the management of endometriosis.

Progestagens and anti-progestagens for pain associated with endometriosis

BACKGROUND

Endometriosis is a gynaecological condition that presents either with the problem of infertility or with painful symptoms. The clinical observation of an apparent resolution of symptoms during pregnancy gave rise to the concept of treating patients with a pseudo-pregnancy regime. Initially combinations of high dose oestrogens and progestagens were used but this was subsequently replaced by progestogens alone. More recently progestogens of both progestagens and anti-progestagens in the treatment of symptomatiprogestogenssis

OBJECTIVES

To determine the effectiveness of both the progestagens and anti-progestagens in the treatment of painful symptoms ascribed to the diagnosis of endometriosis.

SEARCH STRATEGY

The search strategy of the Menstrual Disorders and Subfertility Group was utilised to identify all publications which described or might have described randomised trials of any progestagen or any anti-progestagen in the treatment of symptomatic endometriosis.

SELECTION CRITERIA

Trials were included if they were randomised and considered the effectiveness of either a progestagen or an anti-progestagen in the treatment of painful symptoms associated with endometriosis.

DATA COLLECTION AND ANALYSIS

Seven studies were considered to be appropriate for inclusion in this review. Only three studies evaluating progestagens were included (comparison with placebo, danazol and oral contraceptive plus danazol). All other studies compared the anti-progestagen, gestrinone, with other medical therapies.

MAIN RESULTS

Progestagens appear to be an effective therapy for the painful symptoms associated with endometriosis. Gestrinone is as effective as other established medical therapies (danazol and GnRH analogues).

REVIEWER'S CONCLUSIONS

The limited available data suggests that both continuous progestagens and anti-progestagens are effective therapies in the treatment of painful symptoms associated with endometriosis. Progestagens given in the luteal phase are not effective. These conclusions should be accepted cautiously due to a lack of data.

Biases in the endometriosis literature. Illustrated by 20 years of endometriosis research in Leuven

AIM

To review the Leuven data on endometriosis to demonstrate the shifts that occurred over the years in diagnosis of endometriosis, classification of women with endometriosis and thus in interpretation of results.

RESULTS

The contributions to the LUF syndrome, to non-pigmented endometriosis, to cystic ovarian endometriosis, to deep endometriosis, to endometriosis as an immunologic disease and to the development of an animal model of endometriosis, illustrate the persistent interest in endometriosis over 20 years. Using these data it can be shown how progressively the recognition of endometriosis caused important shifts from women who in the beginning of this period were classified as normal, to women who later became classified as having minimal or mild endometriosis. This was caused initially by the active search for small typical lesions and later by the recognition of non-pigmented lesions as endometriosis. The second important shift was caused by the recognition that deep endometriosis is not only a frequent disease, but that these women are predominantly classified as having mild to moderate endometriosis and even as women without endometriosis. The third shift is still ongoing, since the deep lesions reported become progressively smaller, by the "enthusiasm" of the surgeons, and by the introduction of a menstrual clinical exam. A fourth bias in the literature concerns the diagnosis and treatment of cystic ovarian endometriosis. Together with these shifts in recognition and treatment of endometriosis, our understanding of the physiopathology of endometriosis has changed. This is illustrated by the new concepts which have emerged over this period. These are, the focal treatment of cystic ovarian endometriosis, the concept that mild endometriosis could be a normal physiological condition and the endometriotic disease theory.

CONCLUSION

To interpret the data of the literature we should be aware of the shifts that have occurred in the classification of endometriosis over the past 20 years, and which still can hamper the comparison of results between research groups.