Is Neonatal Uterine Bleeding Involved in Early-Onset Endometriosis?

BACKGROUND

There has been considerable progress in our understanding of endometriosis, but its pathophysiology remains uncertain. Uncovering the underlying mechanism of the rare instances of endometriosis reported in early postmenarcheal years and in girls before menarche can have wide implications.

METHODS

We conducted a literature review of all relevant articles on Medline.

RESULTS

In the review, we explore the pathogenetic theories of premenarcheal endometriosis, the role of retrograde menstruation in the adult and its potential role in early-onset disease, as well as the factors that argue against the existence of a link between early-onset endometriosis (EOE) and neonatal uterine bleeding (NUB).

CONCLUSIONS

As with endometriosis in adult women, the pathogenesis of early-onset disease remains unclear. A link between NUB and EOE is plausible, but there are considerable challenges to collating supporting evidence. The state of our understanding of early uterine development and of the pathophysiology of NUB leaves many unknowns that need exploration. These include proof of the existence of viable endometrial cells or endometrial mesenchymal stem cells in NUB, their passage to the pelvic cavity, their possible response to steroids, and whether they can reside within the pelvic cavity and remain dormant till menarche.

Endometriosis: Age at diagnosis and the severity of the disease

BACKGROUND

Endometriosis is often described as a progressive disease beginning with menarche and menstrual bleeding. However, this is controversial, as the origin of the disease remains unknown. The objective of this study was to investigate the association between the severity of endometriosis and age at initial diagnosis.

MATERIAL AND METHODS

This prospective multicenter cohort study included 964 patients, newly and histologically diagnosed with endometriosis during laparoscopic treatment. The main outcome measures were diagnostic lesions with staging according to rAFS (revised American Fertility Society) scores, intensity of pain based on VAS (Visual Analog Scale) scores and quality of life from SF-36 questionnaire results. Age was treated as a categorical variable. Univariate and multivariable analyses (linear and multinomial ordinal) were conducted taking into account two by two multiple comparisons. The results were expressed with effect sizes and 95 % confidence intervals.

MAIN FINDINGS

No significant association between age and rAFS stage was found (p = 0.053). The percentage of patients with a deep nodule ≥ 2 cm was respectively 20 %, 25 %, 21 %, 18 % and 9 % for patients aged ≤ 25, 26-30, 31-35, 36-40 and >40 years respectively (p = 0.005). For dysmenorrhea, 64 %, 61 %, 54 %, 51 % and 32 % of patients aged ≤25, 26-30, 31-35, 36-40 and >40 years respectively reported a VAS score of ≥7 (p ≤ 0.001).

CONCLUSION

Prospective data obtained in patients newly diagnosed with endometriosis, revealed that the rAFS score is not related to patient age, and that the percentage of patients with a nodule ≥ 2 cm and severe dysmenorrhea did not increase with age. These percentages were significantly lower in patients aged > 40.

A 24-months Follow-up Study of Individuals with Endometriosis using Transvaginal Ultrasound

STUDY OBJECTIVE

To investigate the progression of deep infiltrating endometriosis using transvaginal ultrasound surveillance of patients undergoing conservative management.

DESIGN

Retrospective single cohort.

SETTING

Australian tertiary university hospital PATIENTS: One hundred twenty two women with endometriosis proven on transvaginal ultrasound who had not undergone surgical management.

INTERVENTIONS

The progression of endometriosis lesions demonstrated on transvaginal ultrasound in women receiving conservative management over the course of 24 months.

MEASUREMENTS AND MAIN RESULTS

A total of 122 patients fulfilled the inclusion criteria. All women had 2 ultrasounds that were performed at least 6 months apart. The median follow-up time was 490.5 days (255.4-725.6). At second scan, 22% (95% CI: 15-30%) of cohort experienced an increase in the number of endometriosis nodules compared to first scan, with 51% (95% CI: 42-60%) remaining static while 27% (95% CI: 19-35%) experienced a decrease. While there was no statistically significant difference in the volumes of uterosacral ligament, retro cervical, and bowel endometriosis, endometrioma volumes were significantly lower at second scan (Median = 3.24 mL, IQR = 0.6-16.87) as compared to the first scan (Median = 7.41 mL, IQR = 2.04-28.95), p <.001.

CONCLUSION

Individuals with deep infiltrating endometriosis are unlikely to see significant disease progression over time. Both surgical and nonsurgical interventions are effective in managing endometriosis in terms of endometriotic nodule size and number, as measured by ultrasound.

The Impact of Endometriosis on Pregnancy

Despite the increased frequency of endometriosis, it remains one of the most enigmatic disorders regarding its effects on pregnancy. Endometriosis adversely affects both natural and assisted conception. Impaired folliculogenesis, which causes follicular dysfunction and low egg quality, as well as luteal phase problems, reduced fertilization, and abnormal embryogenesis, are some of the mechanisms advocated to explain reproductive dysfunction. There is a rising need for a comprehensive study of the potential negative consequences of this condition on pregnancy outcomes, including the postpartum period, as more women with a medical history of endometriosis become pregnant. Obstetrical complications (small for gestational age [SGA], cesarean section [CS], miscarriage, hemorrhage, low placental adhesion, and preterm delivery) are statistically elevated in women with endometriosis. Furthermore, ruptured ovarian endometrioma, appendicitis, intestinal perforation, and hemoperitoneum have been described in pregnancy. Obstetricians are largely unfamiliar with these complications, as they have not been thoroughly investigated. The development and pathogenesis of endometriosis is an important field of study and has not yet been fully elucidated. Finding these mechanisms is crucial for the development of new and more effective strategies to treat this condition. Endometriosis can have an impact on obstetric and neonatal outcomes of pregnancy, in addition to its potential effects on conception. To date, no additional monitoring is recommended for pregnancies with a history of endometriosis. However, more studies are urgently needed to assess the need for the tailored pregnancy monitoring of women with endometriosis.

Deep Infiltrating Endometriosis in Adolescence: Early Diagnosis and Possible Prevention of Disease Progression

Endometriosis has a prevalence of 10% worldwide in premenopausal women. Probably, endometriosis begins early in the life of young girls, and it is commonly diagnosed later in life. The prevalence of deep infiltrating endometriosis (DIE) in adolescence is currently unknown due to diagnostic limits and underestimation of clinical symptoms. Dysmenorrhea is a common symptom in adolescents affected by DIE, often accompanied by dyspareunia and chronic acyclic pelvic pain. Ultrasonography-either performed transabdominal, transvaginal or transrectal-should be considered the first-line imaging technique despite the potential for missed diagnosis due to early-stage disease. Magnetic resonance imaging should be preferred in the case of virgo patients or when ultrasonographic exam is not accepted. Diagnostic laparoscopy is deemed acceptable in the case of suspected DIE not responding to conventional hormonal therapy. An early medical and/or surgical treatment may reduce disease progression with an immediate improvement in quality of life and fertility, but at the same time, painful symptoms may persist or even recur due to the surgery itself. The aim of this narrative review is to report the prevalence of DIE in adolescents, describe the pathogenetic theories and discuss the management in adolescent women, including the challenging road to diagnosis and the treatment alternatives.

Identification of central genes for endometriosis through integration of single-cell RNA sequencing and bulk RNA sequencing analysis

This study aimed to identify the key genes involved in the development of endometriosis and construct an accurate predictive model to provide new directions for the diagnosis and treatment of endometriosis. Using bioinformatics analysis, we employed the single-cell cell communication method to identify the key cell subtypes. By combining chip data and integrating differential analysis, WGCNA analysis, and the least absolute shrinkage and selection operator (LASSO) model, key genes were identified for immune infiltration and functional enrichment analyses. Cell communication analysis identified tissue stem cells as the key subtype. Differential analysis revealed 1879 differentially expressed genes, whereas WGCNA identified 357 module genes. The LASSO model further selects 4 key genes: Adipocyte Enhancer Binding Protein 1(AEBP1), MBNL1, GREM1, and DES. All 4 key genes showed significant correlations with immune cell content. Moreover, these genes were significantly expressed in single cells. The predictive model demonstrated good diagnostic performance. Through scRNA-seq, WGCNA, and LASSO methodologies, DES, GREM1, MBNL1, and AEBP1 emerged as crucial core genes linked to tissue stem cell markers in endometriosis. These genes have promising applications as diagnostic markers and therapeutic targets for endometriosis.

Natural progression of deep pelvic endometriosis in women who opt for expectant management

INTRODUCTION

The natural history of endometriosis is poorly understood, and despite numerous studies, the rate of the disease progression and optimal treatment planning in women who are asymptomatic or experience mild symptoms not requiring treatment are unknown. The aim of this study was to assess the behavior of deep endometriosis in women who are managed expectantly without any medical or surgical intervention.

MATERIAL AND METHODS

A retrospective cohort study of women diagnosed with deep endometriosis on transvaginal ultrasound scan at the Department of Gynecology, University College London Hospitals and The Gynecology Ultrasound Centre, London, UK, from April 2007 to April 2022. All women attended for at least two ultrasound scans which were carried out by a single expert ultrasound examiner and at least 6 months apart. The number and position of endometriotic nodules were recorded, and the mean diameter of each nodule was calculated from measurements taken in three orthogonal planes.

RESULTS

During the study period, 1922 women were found to have moderate or severe deep endometriosis on pelvic ultrasound examination. A total of 135 premenopausal women who were managed expectantly fitted the inclusion criteria. The median number of endometriotic nodules per woman at the initial visit was 2 (range: 0-7), and the median follow-up time was 666 days (181-2984). In the follow-up period, 50/135 women (37%, 95% CI: 29-46) developed additional nodules or experienced an increase in nodule size, and 17/135 women (13%, 95% CI: 8-19) had a regression in the number or size of the nodules. In the remaining 68/135 women (50%, 95% CI: 42-59) the disease remained static during the follow-up. The median change in mean diameter of nodules during the study period per woman was +0.13 mm (-11.67 - +5.83), with an annual growth rate of +0.09 mm/year (-6.65 - +6.45).

CONCLUSIONS

In our study we found evidence of deep endometriosis progression in just over a third of women. In view of this, asymptomatic or mildly symptomatic women diagnosed with deep endometriosis could be reassured that their disease is unlikely to worsen with time.

In Memory of Ivo Brosens: Reflections on the Pathophysiology of Neonatal Uterine Bleeding

BACKGROUND

The occurrence of vaginal bleeding in early neonatal life has been observed for centuries and was considered a consequence of the sudden drop in circulating hormones following birth. As such, neonatal uterine bleeding was dismissed as having no clinical significance. Interest in the phenomenon was renewed when a new theory suggested a link between neonatal uterine bleeding (NUB) and accelerated endometrial maturation. This theory was based on the observation of a higher incidence of NUB in babies born post-term or after pregnancies complicated by intrauterine growth restriction, preeclampsia, or blood group incompatibility.

OBJECTIVE

The objective of this study was to review of available evidence on the pathogenesis of NUB.

METHOD

Review of available literature using Medline search (August 2022, no limit on start date or language) to identify articles that may link NUB with features of the uterus and/or endometrium.

OUTCOME

The fetal endometrial responses differ from that of the adult. In the fetus, the endometrium features progestogenic response only in a minority of cases. The endometrium in most newborn girls does not exhibit secretory or decidual changes which indicate lack of progesterone response. Most newborn girls do not have visible bleeding. Animal studies linked exogenous progestogen exposure during the period of organogenesis to poor endometrial gland development, progesterone resistance, and to alterations of reproductive performance. Although the fetal endometrium may not exhibit a full proliferative response, it is clearly sensitive to circulating estrogens. Molecular mechanisms involved in NUB may include "ontogenetic progesterone resistance."

CONCLUSION AND OUTLOOK

Endometrial development and its response to withdrawal of hormones at birth varies and may be affected by intrauterine stressors and gestational age. Factors that affect endometrial development during fetal life and in preterm neonates can have implications on future reproductive performance.

Is neonatal uterine bleeding responsible for early-onset endometriosis?

BACKGROUND

It has been hypothesized that the origin of early-onset endometriosis could be from endometrial mesenchymal stem cells (eMSCs) in neonatal uterine blood (NUB). There is no information on the possible mechanistic basis linking an association between NUB/neonatal endometrium and development of early-onset endometriosis. In this study we performed a series of experiments to clarify the mechanistic link between NUB and/or neonatal endometrium and development of early-onset endometriosis.

METHODS

We retrospectively collected postmortem neonatal endometria (n = 15) and prospectively collected NUB (n = 18) of female babies for the analysis of different biological markers including eMSCs. Immunohistochemical analysis of neonatal endometria was performed to examine the expression patterns of ovarian steroid receptors (ER/PGR), decidualization (prolactin, IGFBP1), pre-decidualization (Glycodelin A, α-SMA), proliferation (Ki-67 index), vascularity (CD31 + cells), immunocompetent CD68+, CD45+, CD56 + cells and some putative markers of eMSCs. Cell transfer method and immunocytochemistry were used to investigate the eMSCs and/or endometrial cells in NUB.

RESULTS

Immunohistochemical analysis of postmortem neonatal endometria revealed variable staining response to ER/PGR, decidual markers, and substantial proliferative and angiogenic activity. A moderate to strong immunoexpression of Glycodelin-A was found in both neonatal and adult endometria. The tissue infiltration of CD56+, CD45 + and CD68 + immunocompetent cells was significantly low in neonatal endometria than that in adult endometria (p = 0.0003, p < 0.0001, p = 0.034, respectively). No eMSCs or even endometrial cells were detected in NUB. However, a variable expression of some phenotypes of eMSCs (CD90/CD105) was found in neonatal endometria.

CONCLUSIONS

Based on our serial experiments we did not find any supporting evidence for the role of NUB in early-onset endometriosis. Neonatal endometria showed variable expression of ovarian steroid receptors, decidualization, and a substantial amount of proliferative and angiogenic activity. As an alternative mechanism, a significantly less tissue accumulation of immunocompetent cells in neonatal endometria may explain the survival of ER + and PGR + cells should they make entry into the pelvis and consequent development of early endometriosis with the onset of ovarian function. Future study with large sample size and application of modified technological tools is warranted to test the NUB hypothesis and to clarify their biological or clinical significance.

TRIAL REGISTRATION

not applicable.

Endometriosis: A Review of Clinical Diagnosis, Treatment, and Pathogenesis

Endometriosis is a condition that affects women of reproductive age, and it is distinguished by the development of endometrial-like tissue outside the uterine cavity. It is frequently accompanied by persistent pelvic discomfort and infertility. This investigation looks into recent findings on clinical manifestation to help doctors and improve women's health. PubMed and Google Scholar were used to review on clinical diagnosis of endometriosis. The search strategy contained the terms “endometriosis” and “clinical diagnosis.” All research articles published between 1960 and 2021 were included in the search. The findings were then categorized to summarize the evidence. There was a total of 29 instances of endometriosis discovered. The patients' ages varied from 20 to 45 years old, with a median of 28.8 years and a mean of 29.4±7.7 years. Dysmenorrhea is a common disorder among adolescent girls experiencing various physical and emotional symptoms which have a detrimental influence on their quality of life. In this study, scar endometriosis was shown to be the more common variety of endometriosis, with 50% of cases predominantly developing at the lower segment cesarean section (LSCS) scar site. As a result, women with endometriosis are more likely to have miscarriages, and the quality of their embryos declines as a result.

Medical and Behavioral Aspects of Adolescent Endometriosis: A Review of the Literature

The majority of young women will experience discomfort associated with menstrual cycles and miss out on education and social opportunities. Endometriosis, the presence of endometrial glands and stroma outside of uterus, is the most common cause of secondary dysmenorrhea and characterized by pain despite treatment with nonsteroidal anti-inflammatory drugs and hormonal agents. The true prevalence of adolescent endometriosis is not clear. Delay in diagnosis leads to persistent pain, affects quality of life, and potentially contributes to disease progression and subfertility. A laparoscopic diagnosis is the gold standard, but the surgical appearance may differ from adults, as endometriotic lesions are usually red or clear, making their identification a challenge for gynecologists who are unexperienced with endometriosis in adolescents. A personalized medical–surgical treatment is regarded as the most effective therapeutic strategy to achieve remission of symptoms, suppress disease progression, and protect future fertility. Studies have demonstrated how adolescent endometriosis negatively affects patients’ quality of life and psychosocial functioning. Development of therapeutic interventions targeting psychosocial function and quality of life is imperative for adolescent patients.

A Revised Stem Cell Theory for the Pathogenesis of Endometriosis

During the past decade, a stem cell-based hypothesis has emerged (among many others) to explain the pathogenesis of endometriosis. The initial hypothesis proposed that endometriosis arose from a single or a few specific cells with stem cell properties, including self-renewal and multi-lineage cell differentiation. The origins of the endometriosis-initiating stem cells were thought to be the bone marrow, uterine endometrium, and other tissues. Based on the implantation or metastatic theory in combination with the initial stem cell theory, one or a few multipotent stem/progenitor cells present in the eutopic endometrium or bone marrow translocate to ectopic sites via fallopian tubes during menstruation, vasculolymphatic routes, or through direct migration and invasion. Subsequently, they give rise to endometriotic lesions followed by differentiation into various cell components of endometriosis, including glandular and stromal cells. Recent somatic mutation analyses of deep infiltrating endometriosis, endometrioma, and eutopic normal endometrium using next-generation sequencing techniques have redefined the stem cell theory. It is now proposed that stem/progenitor cells of at least two different origins—epithelium and stroma—sequentially, differentially, but coordinately contribute to the genesis of endometriosis. The dual stem cell theory on how two (or more) stem/progenitor cells differentially and coordinately participate in the establishment of endometriotic lesions remains to be elucidated. Furthermore, the stem/progenitor cells involved in this theory also remain to be identified. Given that the origin of endometriosis is eutopic endometrium, the candidate cells for endometriotic epithelium-initiating cells are likely to be endometrial epithelial cells positive for either N-cadherin or SSEA-1 or both. The candidate cells for endometriotic stroma-initiating cells may be endometrial mesenchymal stem cells positive for SUSD2. Endometrial side population cells are also a possible candidate because they contain unipotent or multipotent cells capable of behaving as endometrial epithelial and stromal stem/progenitor cells.

Age‐dependent phenotypes of ovarian endometriomas

Purpose

To analyze the characteristics of the ovarian endometrioma (OE) across the life span of a woman. In the past, the OE has traditionally been viewed as a single, monolithic disease. Today, there are emerging data indicating that OE phenotypes differ according to the age of the woman.

Method

A narrative review of original articles on OE indexed by PubMed.

Results

When appearing in infancy and early adolescence, OE may be the consequence of endometrial cells retrogradely shed with neonatal uterine bleeding. The post‐menarcheal variant, manifesting itself during full adolescence, is singularly frequent in the presence of vaginal or uterine outflow obstructive anomalies. The typical and most frequent adult phenotype is characterized by increasing fibrosis and a tendency to progress; its mere presence exerts a detrimental effect on the surrounding healthy ovarian tissue. In postmenopause, an old lesion may be reactivated in the presence of exogenous or endogenous estrogens, or even be produced ex novo; rarely, it can spread to a variety of organs and structures and even degenerate causing malignancies.

Conclusions

Given the existence of these variants, it is important to agree on management guidelines that take into consideration these different phenotypes.

Traditionally, ovarian endometriomas are considered rightfully as one subtype of endometriosis that is different from other subtypes. Beyond that, it is considered as a monolithic disease entity. In this review, we synthesized published data and argue that this subtype actually has age‐dependent phenotypes, and as such, management should be ideally tailored to achieve the best results.

Immunology and Immunotherapy of Endometriosis

Endometriosis is one of the most common gynecological and systemic diseases, with a remarkable immune background. Patients suffer from pain and fertility reduction. Due to the distinct immune component, an immunotherapeutic approach may gain importance in the future. In endometriosis, shifts in the cell fractions of the immune system are well known. Moreover, hypoxia concomitant with inflammation causes a disturbed immune response. The removal of endometriosis has a therapeutic effect, normalizes the immune disorders, and remains the most effective causative treatment in terms of pain and infertility. A key issue is whether a similar effect can be achieved for fertility with non-invasive immunotherapy where surgery is inadvisable or cannot be performed for various reasons. Numerous immunotherapy trials, including vaccines, were conducted on animals only, although the research is encouraging. Among the promising methods of non-specific immunotherapy is the administration of an ethiodized oil contrast. Moreover, due to the significant successes of immunotherapy in oncology, the possibility of immunotherapy affecting NK cells has been postulated. NK cells are responsible for the surveillance and apoptosis of ectopic cells. Expanding the arsenal of endometriosis treatment by immunotherapy is promising due to the significant contribution of immunological factors and the limitations of current treatment methods.

Adolescent Endometriosis

Importance

Endometriosis is a major health concern in the adolescent population and significantly impacts daily physical and psychosocial functioning. Endometriosis can have differing presentations in this population, and the diagnosis often involves long delays and multiple visits to specialists.

Objective

The aim of this review is to discuss adolescent endometriosis, factors specific to this population, accurate diagnosis, and evidence-based surgical and medical management.

Evidence Acquisition

Computerized searches on the topic of endometriosis and adolescent endometriosis were completed. References from identified sources were then searched manually to allow for a thorough review. Data from relevant sources were synthesized to create the review.

Results

The literature supports endometriosis as a frequent cause of secondary dysmenorrhea. The characteristics of adolescents with endometriosis are shown to differ from those of adults. Initial medical therapy includes nonsteroidal anti-inflammatory drugs and combined hormonal contraceptives, but laparoscopy does have a role in the adolescent population, particularly those who have inadequate response to these treatments. Adolescent endometriosis may have a different appearance and be of all stages. Medical therapies are similar to that of the adult population; however, the benefits of medical and surgical management must be tailored to the adolescent patient.

Conclusions and Relevance

Adolescent endometriosis is likely a more prevalent cause of dysmenorrhea than currently appreciated. A high index of suspicion combined with recognition of risk factors and history-based markers of endometriosis may help identify adolescent endometriosis earlier and avoid delays in diagnosis. Expert opinion supports earlier laparoscopic evaluation in patients with symptoms unresponsive to oral medications, those who have failed initial medical therapy, or those who have evidence of deeply invasive disease, such as an endometrioma. Surgeons should be familiar with the unique appearance of lesions in the adolescent and understand the evidence as it relates to surgical therapy. Postoperative medical management is generally advocated by many, although the efficacy remains unclear at present.

Endometriosis in adolescent and young women

Endometriosis in adolescence represents a specific variant of the disease with its own characteristics and, in some cases, even a possibly different pathogenesis. It has its own clinical presentation, diagnostic and therapeutic modalities. The condition is not rare as once thought and certainly deserves attention in view of increasing evidence of its likely progressive nature. Numerous theories for Its pathogenesis have been formulated and they have been divided into two main categories: the 'in-situ' and the 'transplantation' hypotheses. Clinical manifestations include as the prevailing symptom a persistent chronic pelvic pain, despite medical treatment, manifested under various forms: dysmenorrhea, acyclic chronic pain, acute abdominal pain and migraines. These symptoms can substantially affect the quality of life on an adolescent. At histopathology, adolescent endometriosis is characterized by a high proportion of subtle, clear, red or vesicular implants and by the rarity of deep nodules. Frequently, the picture includes ovarian endometriomas. In some adolescent girls, lesions may regress or even disappear, probably through immune suppression; in others, chronic stress, unhealthy diet or lifestyle such as high-fat diet, may accelerate lesional progression and cause symptoms. Classically, management of adolescent endometriosis has been centered on attempts to treat dysmenorrhea; today both medical and surgical modalities have the potential to improve quality of life, alleviate symptoms, prevent the development of more severe disease and minimize risks for future fertility in adolescents. Nonetheless, at present, medical treatments are considered the first line of interventions in treating young women.

The Importance of Stromal Endometriosis in Thoracic Endometriosis

Thoracic endometriosis (TE) is a rare type of endometriosis, where endometrial tissue is found in or around the lungs and is frequent among extra-pelvic endometriosis patients. Catamenial pneumothorax (CP) is the most common form of TE and is characterized by recurrent lung collapses around menstruation. In addition to histology, immunohistochemical evaluation of endometrial implants is used more frequently. In this review, we compared immunohistochemical (CPE) with histological (CPH) characterizations of TE/CP and reevaluated arguments in favor of the implantation theory of Sampson. A summary since the first immunohistochemical description in 1998 until 2019 is provided. The emphasis was on classification of endometrial implants into glands, stroma, and both together. The most remarkable finding is the very high percentage of stromal endometriosis of 52.7% (CPE) compared to 10.2% (CPH). Chest pain, dyspnea, right-sided preference, and diaphragmatic endometrial implants showed the highest percentages in both groups. No significant association was found between the recurrence rate and the various appearances of endometriosis. Sometimes in CPE (6.8%) and CPH (30.6%) no endometrial implants were identified underlining the importance of sensitive detection of endometriosis during and after surgery. We suggest that immunohistochemical evaluation should become mandatory and will improve diagnosis and classification of the disease.

Neonatal Uterine Bleedings: An Ignored Sign but a Possible Cause of Early-Onset Endometriosis - A Systematic Review

OBJECTIVE

Based on the hypothesis that neonatal uterine bleedings (NUB), occurring mostly in the first week after birth, could represent a pathogenetic mechanism for early-onset endometriosis, this systematic review (SR) was undertaken to evaluate the prevalence and screening strategies used to assess and quantify NUB.

DESIGN

Both a SR and a sample literature search in PubMed and Embase were conducted to gather information on NUB prevalence and screening techniques. This was performed by an information specialist. Only full-text articles regarding the assessment of NUB in neonates in the first 2 weeks after birth were included. No limit on language or publication data was used.

MATERIALS AND METHODS

The SR was registered in PROSPERO (CRD42019138121). Data was first assessed for eligibility on title and abstract by 2 blinded review authors. Any disagreements were discussed with a third reviewer if necessary. Subsequently, full-text articles were read and assessed for quality using the Cochrane Collaboration Handbook.

RESULTS

Out of 1,988 articles in the systematic search, 10 relevant articles were selected, of which 8 were identified through the systematic search and 2 were found through other sources. The sample search of 4,445 articles did not bring up relevant articles. Results were not comparable due to the heterogeneity of screening techniques, although data showed consensus. The prevalence of visible bleeding ranged from 3.3 to 53.8% and the prevalence of occult bleeding from 25.4 to 96.7%. The occurrence was the highest between the 3rd and 7th day postpartum (PP) and the bleeding lasted for 3-4 days on average. Various screening techniques for detecting NUB were found in the literature, including the use of hemoglobin detection devices (such as Hemastix) in the vaginal vestibulum, comparison of diapers with stains of known volume, colposcopy, and ultrasonography.

CONCLUSION

The reported prevalence of NUB varies considerably, with a consistent occurrence between the 3rd and the 7th day PP. Literature to assess NUB is dated. The techniques are poorly described and heterogeneous. Future research should focus on prospective cohort studies in order to attempt to correlate NUB cases to (early-onset) endometriosis.

Cellular Origins of Endometriosis: Towards Novel Diagnostics and Therapeutics

Endometriosis remains an enigmatic disease of unknown etiology, with delayed diagnosis and poor therapeutic options. This review will discuss the cellular, physiological, and genomic evidence of Sampson's hypothesis of retrograde menstruation as a cause of pelvic endometriosis and as the basis of phenotypic heterogeneity of the disease. We postulate that collaborative research at the single cell level focused on unlocking the cellular, physiological, and genomic mechanisms of endometriosis will be accompanied by advances in personalized diagnosis and therapies that target unique subtypes of endometriosis disease. These advances will address the clinical conundrums of endometriosis clinical care—including diagnostic delay, suboptimal treatments, disease recurrence, infertility, chronic pelvic pain, and quality of life. There is an urgent need to improve outcomes for women with endometriosis. To achieve this, it is imperative that we understand which cells form the lesions, how they arrive at distant sites, and what factors govern their ability to survive and invade at ectopic locations. This review proposes new research avenues to address these basic questions of endometriosis pathobiology that will lay the foundations for new diagnostic tools and treatment pathways.

Commentary: Novel Use of Offset Analgesia to Assess Adolescents and Adults with Treatment Resistant Endometriosis-Associated Pain

Background and Objective

Endometriosis, affecting approximately 176 million adults and adolescents worldwide, is a debilitating condition in which uterine tissue grows outside the uterus. The condition costs the US economy approximately $78 billion annually in pain-related disability. By understanding the neural underpinnings of endometriosis-associated pain (EAP) and risk factors for chronification, translational research methods could lessen diagnostic delays and maximize successful pain remediation. This can be accomplished by the novel use of a known method, offset analgesia (OA), to better elucidate the neural mechanisms that may contribute to and maintain EAP. This commentary will provide justification and rationale for the use of OA in the study of EAP.

Conclusion

Utilizing an OA paradigm in patients with endometriosis, especially adolescents, may (1) provide insight into neural mechanisms contributing to pain maintenance, which could capture those at-risk for the transition to chronic pelvic pain, (2) provide a metric for the development of future centrally mediated treatment options for this population, and (3) elucidate the brain changes that result in resistance to treatment and pain chronification.

Evidence in Support for the Progressive Nature of Ovarian Endometriomas

CONTEXT

Whether endometriosis is a progressive disease is a highly contentious issue. While progression is reported to be unlikely in asymptomatic deep endometriosis, progression in symptomatic deep endometriosis has recently been reported, especially in menstruating women. However, pathophysiological reasons for these differences are unclear.

OBJECTIVE

This study was designed to investigate whether ovarian endometrioma (OE) is progressive or not.

SETTING, DESIGN, PATIENTS, INTERVENTION AND MAIN OUTCOME MEASURES

Thirty adolescent patients, aged 15 to 19 years, and 32 adult patients, aged 35 to 39 years, all laparoscopically and histologically diagnosed with OE, were recruited into this study after informed consent. Their demographic and clinical information were collected. Their OE tissue samples were collected and subjected to immunohistochemical analysis for E-cadherin, α-smooth muscle actin (α-SMA), desmin, and adrenergic receptor β2 (ADRB2), as well as quantification of lesional fibrosis by Masson trichrome staining.

RESULTS

OE lesions from the adolescent and adult patients are markedly different, with the latter exhibiting more extensive and thorough progression and more extensive fibrosis, suggesting that lesions in adults progressed to a more advanced stage. Adult lesions and higher staining level of α-SMA and ADRB2 are positively associated with the extent of lesional fibrosis, while the lesion size and the E-cadherin staining are negatively associated.

CONCLUSIONS

Our data provide a more definitive piece of evidence suggesting that OE is a progressive disease, since the adult lesions have had a longer time to progress. In addition, the pace of progression depends on lesional age as well as the severity of endometriosis-associated dysmenorrhea, if any.

Epithelial-Mesenchymal Transition in Endometriosis-When Does It Happen?

Epithelial-mesenchymal transition (EMT) is an important process of cell remodeling characterized by the gradual loss of the epithelial phenotype and progressive gain of a mesenchymal phenotype. EMT is not an all-or-nothing process, but instead a transition of epithelial to mesenchymal cells with intermediate cell states. Recently, EMT was described in endometriosis, and many EMT-specific pathways like Twist, Snail, Slug, Zinc finger E-box-binding homeobox 1/2 (ZEB1/2), E/N-cadherin, keratins, and claudins are involved. However, as pointed out in this review, a comparison of the eutopic endometrium of women with and without endometriosis yielded only subtle changes of these EMT markers. Furthermore, only very few alterations in cell-cell contacts could be found but without changes in the epithelial phenotype. This suggests only a partial EMT which is not a prerequisite for the detachment of endometrial cells and, thus, not critical for the first step(s) in the pathogenesis of endometriosis. In contrast, the majority of changes in the EMT-related marker expression were found in the ectopic endometrium, especially in the three endometriotic entities, ovarian, peritoneal, and deep infiltrating endometriosis (DIE), compared with the eutopic endometrium. In this review, we examine the most important EMT pathways described in endometriosis and propose that partial EMT might result from the interaction of endometrial implants with their surrounding microenvironment.

Endometriosis in adolescence: Early manifestation of the traditional disease or a unique variant?

Little is known about Endometriosis in Adolescents and its prevalence is yet to be estimated. Traditional Endometriosis seems to be, by far, quite different with this unique variant when it comes to clinical presentation, management and course of the disease. Further research needs to be conducted in order to classify these two, phenomenically similar, diseases. Adolescents with a history of dysmenorrhea and chronic pelvic pain (CPP) imply findings suggestive of endometriosis. The severity of the disease is variable, from superficial endometriosis to deep endometriotic lesions or even ovarian endometriomas. The course of the disease also suggests the necessity of a more personalized approach since among adolescents, endometriosis could resolve or even aggravate with no particular pathophysiological pattern. Some studies suggest that appropriate treatment should be based on the understanding of the pathophysiologic mechanisms. Long term course of the disease, as well as, a high recurrence rate pose a difficulty to scientists, deciding conservative over operative surgery. Some believe that early operation on superficial forms of endometriosis could potentially prevent deep endometriotic lesions in the long-run. Others find medication such as, combined oral contraceptive pills (COCPs), progestins, levonorgestrel intrauterine device or gonadotrophin releasing hormone analogues (GnRHa), more appropriate for this age group. Last but not least, operation with post-operative hormonal treatment remains the most common treatment approach. Nevertheless, our limited understanding of the disease, as well as, particular factors needed to be taken into consideration, for instance, bone formation in this age group, underline the necessity of further studies, needed to be appointed, in order to determine the best diagnostic and therapeutic approach.

Dysmenorrhea, Endometriosis and Chronic Pelvic Pain in Adolescents

Most adolescents will experience discomfort during menstruation. Due to normalization of dysmenorrhea, there is delay to diagnosis and treatment. Non-steroidal anti-inflammatories are a first line treatment. Adolescents can safely be offered menstrual suppression with combined hormonal contraception, and progestin-only options. When the above are ineffective, gonadotropin releasing hormone agonists with add back treatment can be considered. Transabdominal ultrasound is indicated when first line treatments do not improve symptoms. Endometriosis should be considered in adolescents who experience ongoing pain despite medical treatment. If laparoscopy is performed and endometriosis visualized, it should be treated with either excision or ablation. Women with endometriosis should be counselled on menstrual suppression until fertility is desired. Management of chronic pain requires the involvement of a multi-disciplinary team.

Ovarian endometrioma - a possible finding in adolescent girls and young women: a mini-review

Young girls before menarche or menstruating adolescent women may experience long-term drug-resistant chronic pelvic pain, as well as other symptoms associated with pelvic mass. In such cases, it is of great importance to consider ovarian endometrioma in the differential diagnosis. In general, endometrioma is recognized as an ovarian cyst. However, in most cases, the pathology represents pseudocyst with a partial or complete endometrial-like lining with extraovarian adhesions and endometriotic implants which are likely to occur at the sites of ovarian adhesions and at the ceiling of the ovarian fossa. Ovarian endometriomas occur in 17–44% patients with endometriosis and account for 35% of all benign ovarian cysts. The time span from the onset of menarche to the time of endometrioma formation, which requires surgical intervention, has been evaluated to be a minimum of 4 years. The pathogenesis of early-life endometrioma may be different from other types of endometriosis. Diagnosis is often delayed, especially in adolescents, who tend to wait too long before seeking professional help. The three specific aims of treatment in adolescents with endometriosis and endometriomas are control of symptoms, prevention of further progression of the disease as well as preservation of fertility. Increasing evidence demonstrates association between ovarian endometriosis and ovarian cancer. In the present mini-review, we draw the particular attention of clinicians to such a possibility, even if relatively infrequently reported.

Relationship between Patient Age and Disease Features in a Prospective Cohort of 1560 Women Affected by Endometriosis

OBJECTIVE

To assess the relationship between age, location of the disease, and surgical procedures performed in patients undergoing surgical management of endometriosis.

DESIGN

Retrospective study using data prospectively recorded in the North-West Inter Regional Female Cohort for Patients with Endometriosis database.

SETTING

University tertiary referral center.

PATIENTS

Women who underwent surgical management of symptomatic endometriosis between April 2009 and April 2014.

INTERVENTIONS

Patients were allocated to 6 groups according to their age at the time of surgery: ≤20, 21 to 25, 26 to 30, 31 to 35, 36 to 40 and >40 years. Patient characteristics, prior history, location of endometriotic lesions, stage of disease, intraoperative findings, and surgical procedures were retrieved from a prospectively recorded database.

MEASUREMENTS AND MAIN RESULTS

Patient characteristics, symptoms, location of endometriosis, and type of surgery performed were compared between groups. In total, 1560 procedures were performed. Of these, more than one-half were carried out in women between the age of 26 to 35 years and the majority were performed in women aged between 26 and 30 years. Only 2% of procedures were performed in women under the age of 20 years. The mean stage of the disease at the time of surgical diagnosis was stage II for women younger than 20 years, stage III for those in the age group of 21 to 25 years, and stage IV for those older than 26 years. The rate of diagnosis of deep colorectal nodules increased progressively from 20 to 26 years and remained stable thereafter.

CONCLUSION

Our data confirm that endometriosis is a disease that probably progresses from adolescence until the adult period when symptoms (pain or infertility) become debilitating and require surgery. Our data suggest that policies relating to the prevention and early diagnosis of endometriosis should focus on women younger than 25 years.

Salpingitis Impairs Bovine Tubal Function and Sperm-Oviduct Interaction

Salpingitis is a common cause for subfertility and infertility both in humans and animals. However, the effects of salpingitis on tubal function and reproductive success are largely unknown. Therefore we set out to investigate the effects of inflammation on sperm and oocyte transport and gameto-maternal interaction in the oviduct using the bovine as a model. For this purpose, oviducts revealing mild (n = 45), moderate (n = 55) and severe (n = 45) inflammation were obtained from cows immediately after slaughter and investigated by live cell imaging, histochemistry and scanning electron microscopy. Our studies showed that endometritis was always correlated with salpingitis. Moderate and severe inflammation caused a significant increase in the thickness of tubal folds (p < 0.05). Severe inflammation was characterized by luminal accumulations of mucus and glycoproteins, increased apoptosis, loss of tight junctions and shedding of tubal epithelial cells. The mean ciliary beat frequency (CBF) in the ampulla was significantly reduced as compared to the controls (p < 0.05). The higher the grade of inflammation, the lower was the CBF (p < 0.001). In severe inflammation, spermatozoa were stuck in mucus resulting in decreased sperm motility. Our results imply that tubal inflammation impairs proper tubal function and leads to reduced sperm fertilizing capacity.

Expression of the TFDP1 gene in the endometrium of women with deep infiltrating endometriosis

The field of endometriosis etiopathogenesis aims to identify the origin of disease in endometrial disorders. Changes in gene and protein expression related to cell adhesion, collagenases, and, mainly, cell cycle regulators have been identified. We set out to analyze the expression of the transcription factor DP-1 (TFDP1) gene, which encodes a protein that controls the G1/S phase passage of the cell cycle, in the endometrium of women with deep infiltrating endometriosis (DIE). Samples of endometrium from both endometriosis-affected women and healthy women were collected, cultured and maintained at the Cell Bank of the Pelvic Pain and Endometriosis Unit of the Federal University of Sao Paulo. This study analyzed five samples from the endometrium cell culture of healthy patients (i.e. no pelvic disease, as determined by means of laparoscopic tubal ligation) and six samples from women diagnosed with DIE. Samples were evaluated for TFDP1 gene expression by real-time PCR. We observed a downregulation of TFDP1 in the endometrium cells of women with DIE when compared to the control (a fold-change of -2.05, p value=.011). The TFDP1 gene is part of the cell cycle pathway, but its function is not yet clear. Additional studies are necessary to clarify the function of TFDP1 in endometriosis etiopathogenesis.

Modern approaches to surgical management of endometrioma

Formation of the ovarian endometrioma consists of implantation, invagination of the ovarian cortex, and adhesion formation. Progression is characterized by repeated injury and repair with degenerative changes. Already with a partially deprived ovarian reserve, resulting from the disease, surgical treatment carries a potential risk of further follicular deprivation. Surgery should therefore be performed with microsurgical precision by experienced hands. Early treatment can possibly prevent further progression. The adverse impact on ovarian reserve of the ablative approach has to be balanced against a lower recurrence rate of a cystectomy. Adapted surgical approaches like a two-step approach or a combination of excisional and ablative surgery has to be considered in case of a large endometrioma. Further studies on the possibility and advantages of sclerotherapy are warranted. Fertility preservation by cryopreservation of ovarian cortex should be part of the informed consent with the patient.

Pathogenesis of endometriosis: the genetic/epigenetic theory

OBJECTIVE

To study the pathophysiology of endometriosis.

DESIGN

Overview of observations on endometriosis.

SETTING

Not applicable.

PATIENT(S)

None.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

The hypothesis is compatible with all observations.

RESULT(S)

Endometriosis, endometrium-like tissue outside the uterus, has a variable macroscopic appearance and a poorly understood natural history. It is a hereditary and heterogeneous disease with many biochemical changes in the lesions, which are clonal in origin. It is associated with pain, infertility, adenomyosis, and changes in the junctional zone, placentation, immunology, plasma, peritoneal fluid, and chronic inflammation of the peritoneal cavity. The Sampson hypothesis of implanted endometrial cells following retrograde menstruation, angiogenic spread, lymphogenic spread, or the metaplasia theory cannot explain all observations if metaplasia is defined as cells with reversible changes and an abnormal behavior/morphology due to the abnormal environment. We propose a polygenetic/polyepigenetic mechanism. The set of genetic and epigenetic incidents transmitted at birth could explain the hereditary aspects, the predisposition, and the endometriosis-associated changes in the endometrium, immunology, and placentation. To develop typical, cystic ovarian or deep endometriosis lesions, a variable series of additional transmissible genetic and epigenetic incidents are required to occur in a cell which may vary from endometrial to stem cells. Subtle lesions are viewed as endometrium in a different environment until additional incidents occur. Typical cystic ovarian or deep endometriosis lesions are heterogeneous and represent three different diseases.

CONCLUSION(S)

The genetic epigenetic theory is compatible with all observations on endometriosis. Implications for treatment and prevention are discussed.

Pathogenesis of endometriosis: Interaction between Endocrine and inflammatory pathways

Despite an estimated prevalence of 11% in women and plausible historical descriptions dating back to the 17th century, the etiology of endometriosis remains poorly understood. Classical theories of the histological origins of endometriosis are reviewed below. Clinical presentations are variable, and signs and symptoms do not correlate well with the extent of disease. In this summary, we have attempted to synthesize the growing evidence that hormonal and immune factors conspire to activate a local inflammatory microenvironment that encourages endometriosis to persist and elaborate mediators of its two cardinal symptoms: pain and infertility. Surprisingly, in the search for novel therapeutics for medical treatment of endometriosis, some compounds appear to have dual pharmacological functions, simultaneously modifying the endocrine and immune system facets of this complex gynecologic syndrome. We predict that these lead drugs will provide more therapeutic choices for patients in the future.

Endometrial stem/progenitor cells and their role in the pathogenesis of endometriosis

Human endometrium regenerates on a cyclical basis each month, likely mediated by endometrial stem/progenitor cells. Several types of stem/progenitor cells have been identified: CD140b⁺CD146⁺ or SUSD2⁺ endometrial mesenchymal stem cells (eMSCs), N-cadherin⁺ endometrial epithelial progenitor cells (eEPs), and side population (SP) cells, a heterogeneous population predominantly comprising endothelial cells. eMSCs reside in a perivascular niche and likely mediate angiogenesis and stromal regeneration. Human eEPs are located in the bases of glands in the basalis and are likely more primitive than SSEA-1⁺ basalis epithelial cells. Endometrial stem/progenitor cells may contribute to the pathogenesis of endometriosis by their retrograde shedding into the pelvic cavity, either after menarche or as a result of neonatal uterine bleeding. eMSCs may have a role in the generation of progesterone-resistant phenotype of endometrial stromal fibroblasts (eSFs) in endometriosis. In future clinical practice, endometrial stem/progenitor cells may be used to establish diagnosis of endometriosis or as therapeutic targets.

Patterns of Bowel Invisible Microscopic Endometriosis Reveal the Goal of Surgery: Removal of Visual Lesions Only

STUDY OBJECTIVE

To document the presence of bowel invisible microscopic endometriosis implants and their relationship with deep endometriosis macronodule infiltrating the bowel.

DESIGN

A series of consecutive patients with deep endometriosis infiltrating the rectum and/or sigmoid colon (Canadian Task Force classification II-2).

SETTINGS

A university referral center.

PATIENTS

Ten patients managed by colorectal resection.

INTERVENTIONS

A microscopic study of endometriotic foci of the bowel involving 3272 microsection slides was established using a unique method of step serial sections using combined transverse and longitudinal macrosection. Two-dimensional reconstruction based on slide scanning highlighted the presence and localization of the deep endometriosis macronodule in contrast with bowel invisible microscopic endometriosis microimplants.

MEASUREMENTS AND MAIN RESULTS

The distance separating the microimplants and the nodule and their histologic characteristics. The mean length of the colorectal specimens was 91 ± 19 mm. The maximum distance between the farthest microimplants was 7.2 cm. The maximum distance from the macroscopic nodule limit to the farthest microimplant was 31 mm. Bowel invisible microscopic endometriosis microimplants presented with similar features independently of the type of spread. They had an active appearance including stroma and glands, were sometimes decidualized, and were free of fibrosis. They were found on the distal/rectal limit of the specimen in 3 patients and on both limits (distal/rectal and proximal/sigmoid colon) in 1 patient.

CONCLUSION

Invisible microscopic endometriosis implants surround the bowel macroscopic endometriosis nodule at variable distances, suggesting that complete surgical microscopic removal may be a challenging goal. These results may help to reconsider the principles and feasibility of the surgical management of bowel endometriosis.

Progress in the diagnosis and management of adolescent endometriosis: an opinion

Increasing evidence indicates that early onset endometriosis (EOE), starting around menarche or early adolescence, may have an origin different from the adult variant, originating from neonatal uterine bleeding (NUB). This implies seeding of naïve endometrial progenitor cells into the pelvic cavity with NUB; these can then activate around thelarche. It has its own pathophysiology, symptomatology and risk factors, warranting critical management re-evaluation. It can also be progressive, endangering future reproductive capacity. This variant seems to be characterized by the presence of ovarian endometrioma. Today, the diagnosis of endometriosis in young patients is often delayed for years; if rapidly progressive, it can severely affect pelvic organs, even in the absence of serious symptoms. Given the predicament, great attention must be paid to symptomatology that is often non-specific, justifying a search for new, simple, non-invasive markers of increased risk. Better use of modern imaging techniques will aid considerably in screening for the presence of EOE. Traditional laparoscopy should be limited to cases in which imaging gives rise to suspicion of severity and a stepwise, minimally invasive approach should be used, followed by medical treatment to prevent recurrence. In conclusion, EOE represents a condition necessitating early diagnosis and stepwise management, including medical treatment.

Examination of the pediatric adolescent patient

Gynecologic examination of the pediatric adolescent patient provides a valuable opportunity for patient education and diagnosis, yet presents special challenges, including achieving comfort for the patient and guardian and finding equipment that are sized for pediatric patient. Anatomic changes due to the hormonal environment evolve from newborn through pubertal development. As pediatric adolescent gynecology has evolved as a specialty, techniques and training for providing optimal office and surgical examination have emerged. Where possible, the patient should be engaged with the examination through use of a mirror or positioning. Smaller swabs should be used for testing for vaginal infection in prepubertal patients. When speculum or office examination is not possible, use of narrow-caliber, flexible, and rigid hysteroscopes allow vaginoscopy for assessment.

Endometriosis in Adolescent and Young Girls: Report on a Series of 55 Cases

STUDY OBJECTIVE

The aim of this retrospective study was to evaluate endometriosis in adolescent and young girls and further to review the menstrual, reproductive characteristics, and risk factors.

DESIGN AND SETTING

We reviewed the medical records of adolescent and young girls with endometriosis from 2 different countries. Data were collected and analyzed from charts of 900 patients with endometriosis.

PARTICIPANTS AND INTERVENTIONS

Fifty-five female adolescents aged between 13 and 21 years (mean age 18.3 years) participated in our series. This study was conducted in the Obstetric and Gynecology Department of Venizeleio General Hospital of Crete and involved all patients diagnosed with endometriosis between 1996 and 2016.

MAIN OUTCOME MEASURES

Statistical methods included χ² and Mann-Whitney U test.

RESULTS

Of 900 patients with endometriosis we found 55 female adolescents (6.1%). The mean age was 18.3 ± 2.3 years, significantly younger compared with the advanced endometriosis patients (32.7 ± 7.2; P < .001). Regarding the menstrual reproductive and others characteristics, we observed several differences in adolescent young girls compared with the advanced age endometriosis group. The factors associated with an increased risk for young women include age at menarche, dysmenorrhea, history of asthma, and a positive family history of endometriosis. Additionally, we report on 16 of 55 (32%) adolescent women with endometriosis and congenital malformations (P < .01) and 5 patients who were diagnosed with dry eye syndrome.

CONCLUSION

There is an association between endometriosis in adolescent and young women and risk factors including early menarche, early onset of dysmenorrhea, history of asthma, previous surgical procedures, obstructive genital anomalies, and family history of endometriosis.

Neonatal uterine bleeding as a biomarker for reproductive disorders during adolescence: a worldwide call for systematic registration by nurse midwife

Neonatal uterine bleeding (NUB) occurs in approximately 5% of newborns and is generally considered to be of little clinical significance. However, the real clinical importance of this condition and its long-term implications remain to be determined. The reason why NUB is rare despite high circulating levels of progesterone can be attributed to a progesterone resistance present in a majority of neonates. Recent work indicates that NUB represents a significant biomarker for events that can occur later-on during adolescence. Indeed, clinical studies have shown that "neonatal menstruation" constitutes a sign of fetal distress during late pregnancy, reflecting a stage of endometrium development that may subsequently have an impact on the reproductive life of the adolescent and the young adult. Via retrograde flow, NUB can cause endometrial stem/progenitor cells to arrive into the pelvic cavity and survive there, dormant underneath the peritoneal surface, until menarche activates them. Indeed, there is both clinical and epidemiological evidence of a link between NUB and adolescent endometriosis. In addition, if progesterone resistance persists till the onset of menarche, in case of an early teen pregnancy, it can result in a disorder of deep placentation. Therefore, we propose that NUB should be carefully recorded so that prospective studies can examine its links with reproductive disorders in adolescence and beyond.

Morphological and immunohistochemical characterization of spontaneous endometriosis in rhesus macaques (Macaca mulatta)

Several cases of spontaneous endometriosis in middle-aged to old rhesus macaques (Macaca mulatta) from the breeding colony of the German Primate Center were thoroughly characterized with regards to anatomical distribution and macroscopic appearance, histological differentiation and immunohistochemical profile including somatic markers, hormonal receptors, and proliferation indices. More than half of the examined animals (five of nine) were directly related to one breeding male, supporting a strong genetic predisposition. Histologically, four different types of endometriotic lesions, depending on the degree of ectopic endometrial gland and stromal differentiation (well differentiated, purely stromal, mixed differentiation, poorly differentiated), could be constantly identified within all animals. Immunohistochemistry (IHC) of cytokeratin (CK), vimentin, smooth muscle actin (SMA), desmin, estrogen (ER), and progesterone (PR) receptors as well as of the nuclear proteins Ki67 and p53 revealed varying staining patterns in the four different types of endometriosis differentiation and compared to normal endometrium. Purely stromal, mixed, or poorly differentiated lesions, especially, showed additional cytokeratin-positive stromal cells, whereas epithelial cells of endometriosis with mixed or poor differentiation increasingly expressed mesenchymal markers (vimentin, SMA). Hormonal receptor and Ki67 expression in well-differentiated endometriotic lesions mostly reflected that of normal endometrial tissue according to the cyclic phase of the animal, while the expression gradually diminished with decreasing grade of differentiation. However, increased nuclear accumulations of p53 antigen could only be continuously detected in epithelial cells of mixed or poorly differentiated endometriosis. Altogether, these findings support the pathogenetic theory of coelomic metaplasia, since the expression profiles of somatic markers in less differentiated forms closely resembled that of mesothelial cells. Thus, the four different histological types of endometriosis might display subsequent grades of differentiation in the course of time, with poorly differentiated types representing newly formed, immature lesions and well-differentiated types being older, fully differentiated forms, rather than being the outcome of dedifferentiation processes.

Promoting awareness of neonatal menstruation

Neonatal uterine bleeding (NUB) has been carefully studied in the past through case reports, small series, clinical cohort studies, pathology investigations of fetal and neonatal. Following a historical recount, this review summarizes biological mechanisms conditioning NUB, starting from the persistence till birth of an 'ontogenetic progesterone resistance' (OPR), causing decreased responsiveness of target tissues to bioavailable progesterone. Several pregnancy-related conditions, such as preeclampsia, fetal growth restriction, prematurity, post-maturity and even Rhesus or ABO incompatibility, influence the occurrence of NUB. It seems therefore that the phenomenon is precipitated by chronic fetal distress. When present, OPR may persists until telarche; as a consequence, if pregnancy occurs in early teenage, the disorder known as "defective deep placentation" may ensue, increasing the risk of obstetrical syndromes. In the presence of NUB, retrograde shedding into the peritoneal cavity of endometrial stem/progenitor and niche cells may occur. There, given the right environment, these cells can survive and become activated at the time of telarche, causing the specific phenotype of early-onset endometriosis. In conclusion, neonatal menstruation is a fetal distress indicator and can alter the incidence of a variety of pathological conditions later in life. For this reason, it should be carefully recorded and the parents informed.

Adult Stem Cells in the Pathogenesis and Treatment of Endometriosis

The human endometrium is a dynamic tissue that undergoes approximately 400 cyclical episodes of proliferation, differentiation, shedding, and regeneration in a woman's reproductive lifespan. The regenerative capacity of human endometrium is likely mediated by adult stem cells. At the cellular level, endometrial mesenchymal stem/stromal cells, located in both the functionalis and basalis layers, support regeneration of the stromal vascular compartment and epithelial progenitor cells, postulated to reside in the basalis epithelium, likely regenerate the glands. Bone marrow adult stem cells, including endothelial progenitor cells, may also participate. Endometriosis can be considered an endometrial proliferative disorder due to dysregulation of the cellular and molecular regenerative processes.

Endometriosis is primarily thought to occur via retrograde menstruation of endometrial debris. It is postulated that endometrial stem/progenitor cells, which have been identified in menstrual blood, are shed into the peritoneal cavity where they adhere to pelvic organs and initiate endometriotic lesions. The homing of bone-marrow-derived adult stem cells to endometriotic lesions is thought to drive progression of the disease.

New drug therapies are urgently required for the treatment of endometriosis due to frequent disease recurrence with current surgical or medical treatments. Medications directly targeting endometrial stem/progenitor cells during menstruation, or following surgery, or targeting bone marrow cell trafficking, are potential targets for future therapies to manage disease initiation and progression.

In this review, we will summarize the current literature on adult stem cell contributions to the development of endometriosis and will then examine the current potential therapies that may target endometrial stem/progenitor cells.

Endometrioma in Adolescents and Future Reproductive Health

There continues to be debate over the nature and progression of ovarian endometriomas in adolescence due to the possibility that they may have a different origin and to the impossibility to be able to predict progress.

The hypothesis of a different origin traces its roots in the phenomenon called “neonatal menstruation” (NUB), occurring in approximately 5% of newborn. The retrograde shedding of neonatal endometrium may contain progenitor cells and stroma that may lie dormant under the peritoneal surface until being activated when estrogens begin to rise.

In teenagers, ovarian endometriomas are often preceded by highly angiogenic implants in the fossa ovarica, with adhesion formation resulting in the invagination of the ovarian cortex and the creation of a pseudocyst.

Use of imaging techniques makes it possible to diagnose even small endometriomas. This is vital to their management, since there is evidence that the disease in an adolescent represents a severe condition, with tendency to progression. In addition, if intervention is decided, the first surgical procedure can determine the ultimate outcome of her reproductive life, because there is a significantly higher risk of inadvertently removing ovarian tissue in the presence of an endometrioma than of other ovarian pathologies. For this reason, techniques avoiding additional trauma to the ovary should be preferred and those who wish to become pregnant should attempt conception as soon as possible; if pregnancy is not sought, hormonal therapy is strongly advised.

Finally, young age at diagnosis may constitute a pivotal factor in considering fertility preservation.