Matteo Schimberni

STUDY QUESTION: Are endometriotic lesions affecting bilateral organs or anatomical structures distributed symmetrically on both sides of the body? SUMMARY ANSWER: The left-sided preponderance of pelvic endometriotic lesions, and the right-sided dominance of thoracic and inguinal lesions, suggest that endometriotic lesions exhibit a non-random, asymmetric lateral distribution. WHAT IS KNOWN ALREADY: Evaluating the anatomical distribution of endometriotic lesions may elucidate the underlying pathogenic mechanism(s) of the disease. If the coelomic metaplasia or embryonic cell remnant theory is correct, a symmetrical right-left pattern would be expected. Conversely, retrograde menstruation would likely result in asymmetrical distribution, influenced by gravity, peritoneal fluid circulation, and anatomical niches. STUDY DESIGN, SIZE, DURATION: This systematic review with meta-analysis included full-length, English-language articles published up to 10 June 2024. Literature searches were performed in PubMed/Medline and Embase databases with the keyword ‘endometriosis’, ‘lateral’, ‘distribution’, ‘right’, ‘left’, and ‘asymmetry’. PARTICIPANTS/MATERIALS, SETTING, METHODS: The review focused on anatomical structures commonly affected by endometriosis with surgically defined right or left laterality: ovaries, uterosacral ligaments, colon, ureters, inguinal regions, and hemithorax (diaphragm, pleura, lungs). Case reports were excluded. Risk of bias was assessed using ROBINS-I for non-randomized studies and a dedicated tool for case series. Meta-analyses of proportions were conducted in R. Heterogeneity was quantified using the I2 statistic. Funnel plots for publication bias and Egger tests were performed using Stata. MAIN RESULTS AND THE ROLE OF CHANCE: Of 6356 articles screened, 154 met the inclusion criteria. A statistically significant left-sided preponderance was observed for ovarian (58%; 95% CI: 57–60%; P < 0.001), uterosacral ligament (56%; 95% CI: 54–59%; P < 0.001), ureteral (71%; 95% CI: 67–76%; P < 0.001), and bowel (72%; 95% CI: 64–79%; P < 0.001) lesions, whereas thoracic (98%; 95% CI: 96–100%; P < 0.001) and inguinal (92%; 95% CI: 83–98%; P < 0.001) lesions were predominantly right-sided. These findings were confirmed in the sensitivity analyses. Egger’s test indicated a possible small study effect only for ovarian lesions (P = 0.012). LIMITATIONS, REASONS FOR CAUTION: The preponderance of retrospective studies, the variability in surgical procedures, and the potential difficulties in accurately distinguishing unilateral from bilateral lesions may have influenced the magnitude of the estimated difference. However, the large patient cohorts, geographical diversity, and consistent asymmetry across lesion types strengthen the results’ validity and generalizability. WIDER IMPLICATIONS OF THE FINDINGS: The pattern of endometriotic lesion distribution, including the opposite asymmetry observed in the pelvis and upper abdomen/thorax, can be explained by factors influencing dissemination and implantation of refluxed endometrial cells. However, it cannot be explained as well by the coelomic metaplasia or embryonic cell remnant theories. This may have important clinical implications, providing a pathogenic basis for secondary prevention strategies. STUDY FUNDING/COMPETING INTEREST(S): The open access facility of this paper was funded by the Italian Ministry of Health, Current research IRCCS Ca’ Granda Ospedale Maggiore Policlinico. P.V. is a member of the Editorial Board of Human Reproduction Open, Journal of Obstetrics and Gynaecology Canada, and International Editorial Board of Acta Obstetricia et Gynecologica Scandinavica; has received royalties from Wolters Kluwer for chapters in UpToDate. All other authors declare no conflicts of interest. REGISTRATION NUMBER: CRD42024511356 (PROSPERO).

Ovarian endometriosis may increase the risk of malignancy. Several studies have suggested atypical endometriosis as the direct precursor of endometriosis-associated ovarian cancer. We performed an advanced, systematic search of the online medical databases PubMed and Medline. The search revealed n = 40 studies eligible for inclusion in this systematic review. Of these, n = 39 were finally included. The results from included studies are characterized by high heterogeneity, but some consistency has been found for altered expression in phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway, ARID1a, estrogen and progesterone receptors, transcriptional, nuclear, and growth factors in atypical endometriosis. Although many targets have been proposed as biomarkers for the presence of atypical endometriosis, none of them has such strong evidence to justify their systematic use in clinical practice, and they all need expensive molecular analyses. Further well-designed studies are needed to validate the evidence on available biomarkers and to investigate novel serum markers for atypical endometriosis.

The aim of this systematic review was to provide comprehensive and available data on the possible role of phytoestrogens (PE) for the treatment of endometriosis. We conducted an advanced, systematic search of online medical databases PubMed and Medline. Only full-length manuscripts written in English up to September 2020 were considered. A total of 60 studies were included in the systematic review. According to in vitro findings, 19 out of 22 studies reported the ability of PE in inducing anti-proliferative, anti-inflammatory and proapoptotic effects on cultured cells. Various mechanisms have been proposed to explain this in vitro action including the alteration of cell cycle proteins, the activation/inactivation of regulatory pathways, and modification of radical oxidative species levels. Thirty-eight articles on the effects of phytoestrogens on the development of endometriotic lesions in in vivo experimental animal models of endometriosis have been included. In line with in vitro findings, results also derived from animal models of endometriosis generally supported a beneficial effect of the compounds in reducing lesion growth and development. Finally, only seven studies investigated the effects of phytoestrogens intake on endometriosis in humans. The huge amount of in vitro and in vivo animal findings did not correspond to a consistent literature in the women affected. Therefore, whether the experimental findings can be translated in women is currently unknown.

To compare pregnancy rate and implantation rate in poor responder women, aged over 40 years, who underwent natural cycle versus conventional ovarian stimulation. This is a retrospective single-center cohort study conducted at the GENERA IVF program, Rome, Italy, between September 2012 and December 2018, including only poor responder patients, according to Bologna criteria, of advanced age, who underwent IVF treatment through Natural Cycle or conventional ovarian stimulation. Between September 2012 and December 2018, 585 patients were included within the study. Two hundred thirty patients underwent natural cycle and 355 underwent conventional ovarian stimulation. In natural cycle group, both pregnancy rate per cycle (6.25 vs 12.89%, respectively, p = 0.0001) and pregnancy rate per patient101 with at least one embryo-transfer (18.85 vs 28.11% respectively, p = 0.025) resulted significant reduced. Pregnancy rate per patient managed with conventional ovarian stimulation resulted not significantly different compared with natural cycle (19.72 vs 15.65% respectively, p = 0.228), but embryo implantation rate was significantly higher in patients who underwent natural cycle rather than patient subjected to conventional ovarian stimulation (13 vs 8.28% respectively, p = 0.0468). No significant difference could be detected among the two groups in terms of abortion rate (p = 0.2915) or live birth pregnancy (p = 0.2281). Natural cycle seems to be a valid treatment in patients over 40 years and with a low ovarian reserve, as an alternative to conventional ovarian stimulation.

Gestational diabetes mellitus (GDM) is a metabolic complication associated with adverse outcomes for mother and fetus. Arsenic (As) exposure has been suggested as a possible risk factor for its development. The aim of this meta-analysis was to provide a comprehensive overview of published evidence on the association between As and GDM. The systematic search from PubMed, MEDLINE, and Scopus was limited to full-length manuscripts published in peer-reviewed journals up to April 2020, identifying fifty articles. Ten studies met the inclusion criteria, nine for quantitative synthesis with a total of n = 1984 GDM cases. The overall pooled risk was 1.56 (95% Confidence Interval - CI = 1.23, 1.99) with moderate heterogeneity (χ² = 21.95; I²% = 64). Several differences among the included studies that may account for heterogeneity were investigated. Stratification for exposure indicator confirmed a positive association for studies assessing urine As. A slightly higher risk was detected pooling studies based in Asia rather than in North America. Stratification for GDM diagnostic criteria showed higher risks when diagnosis was made according to the Canadian Diabetes Association (CDA-SOGC) or World Health Organization (WHO) criteria, whereas a lower risk was observed when adopting the American Diabetes Association (ADA) criteria. These results provide additional evidence for a possible association between As exposure and GDM, although the data need to be interpreted with caution due to heterogeneity.

The presence of endometriosis determines an inflammatory response locally. The objective of this validation study and systematic review was to assess systemic levels of coagulation and inflammatory parameters in women with or without the disease. We conducted a retrospective analysis of a database prospectively collected from January 2017 to February 2020 including n = 572 women who underwent laparoscopic surgery for endometriosis (cases, n = 324) or other benign gynecologic diseases (controls, n = 248). Inflammatory markers and coagulation parameters were determined. An advanced systematic search of the literature on the same parameters was conducted up to April 2020. A significantly higher neutrophil count was found in endometriosis patients. Patients with endometriomas and stage III–IV disease had a significantly lower absolute lymphocyte count and shortened activated partial thromboplastin time (aPTT) values. In the final regression model, aPTT retained significant predictive value for stage III–IV endometriosis (odds ratio (OR) = 0.002, 95% confidence interval (CI) = 0.00–0.445; p = 0.024). Results from the n = 14 included studies in the systematic review are characterized by a high variability, but some consistency has been found for alterations in thrombin time, platelet-to-lymphocyte ratio, and neutrophil count associated with endometriosis. Modest systemic changes of some inflammatory and coagulation parameters are associated with endometriosis. Indeed, all the modifications detected are still within the normal reference intervals, explaining the high heterogeneity among studies.