Microbiota and adenomyosis: exploring mechanisms and therapeutic potential

Objective This review comprehensively explores the potential relationship between the microbiota and adenomyosis, aiming to identify specific microbial biomarkers, elucidate the molecular mechanisms underlying the involvement of the microbiota in the disease, and provide insights into more precise and personalized therapeutic strategies for patients with adenomyosis.

This article adopts the narrative review method to comprehensively analyze the literature on the relationship between the microbiota and adenomyosis. A comprehensive literature search was conducted in PubMed, Embase and Web of Science databases. A total of 8 articles were included, among which one was an animal experiment. This review focuses on analyzing the differences in the composition of the microbiota between patients with adenomyosis and healthy control groups, as well as the potential molecular mechanisms by which the microbiota participates in the development of adenomyosis.

Studies have demonstrated that the composition of the microbiota in women with adenomyosis differs significantly from that in healthy controls.The potential mechanisms by which microbiota may be involved in adenomyosis are closely associated with immune-inflammatory responses and estrogen regulation, which further affect the progression of adenomyosis.

Microbiota may play an important role in the pathogenesis of adenomyosis. Elucidating the specific microbial biomarkers and the underlying molecular mechanisms of microbiota in adenomyosis is crucial for developing novel, precise, and personalized therapeutic strategies, which may provide new options for the treatment of adenomyosis.

Adenomyosis is a benign lesion of the uterine myometrium, characterised histopathologically by ectopic endometrial glands and stroma invading the myometrium, accompanied by proliferation and hypertrophy of surrounding smooth muscle tissue. In recent years, the onset of adenomyosis has tended to occur at a younger age, with most patients presenting with menorrhagia, progressively worsening dysmenorrhoea, and infertility, all of which severely compromise quality of life [Citation1,Citation2]. The aetiology and pathogenesis of adenomyosis remain unclear, and current diagnostic and treatment options have inherent limitations, thereby underscoring the urgent need for further mechanistic research to improve clinical diagnosis and management. The microbiota, as a critical component of the human microenvironment, has attracted increasing attention for its involvement in gynaecologic diseases [Citation3]. Advances in genomics and high-throughput sequencing have revealed significant alterations in the microbiota of women with adenomyosis. Although the precise mechanisms are not yet fully understood, accumulating evidence indicates that the microbiota is closely linked to inflammatory responses and oestrogen [Citation4], and may be involved in the pathogenesis of adenomyosis. This review summarises the latest progress in research on microbiota associated with adenomyosis, delves into the potential mechanisms linking the microbiota to the disease and its therapeutic potential, and suggests that identifying microbial biomarkers and targeted modulation of the microbiota could provide new directions for the treatment of adenomyosis in the future.

Given the broad and exploratory nature of the present study, a narrative review approach was used to comprehensively analyse the literature on the relationship between the microbiome and adenomyosis. This method enables readers to gain a comprehensive understanding of the existing evidence and key interrelationships in this field. Accordingly, a comprehensive literature search was performed in the PubMed, Embase, and Web of Science databases. A total of 8 articles were included, among which one was an animal experiment. The time range covered the relevant literature published from 2010 to 2025. The search formula was constructed using keywords such as ‘adenomyosis, microbiota, dysbiosis, vaginal, endometrial, gut’ combined with free words. We conducted a comprehensive search of clinical studies, basic experiments, narrative reviews, systematic reviews and meta-analyses. We prioritised including relevant studies within the past 5 years that were closely related to the topic. Three researchers independently conducted the literature screening through title and abstract screening and full-text re-screening. Disagreements were resolved through discussion or consultation with a third party. Finally, the literature that met the criteria was included to provide a reliable basis for the review analysis and conclusion derivation (). Microbiota is closely related to gynaecological diseases Microbiota constitutes a vast and complex ecosystem within the human body. These commensal microorganisms colonise diverse sites, including the gut, skin, lungs, oral cavity, and reproductive tract, where they influence health and the development of diseases. Among these, gut microbiota–associated research is the most extensive [Citation5]. Gut microbiome dysbiosis can disrupt host immune regulation, induce chronic inflammation, and promote the development of endometriosis [Citation6]. Furthermore, metabolites produced by the gut microbiota, such as β-glucuronidase and short-chain fatty acids, are also closely associated with the pathogenesis of endometriosis [Citation7,Citation8]. The gut microbiota serves as a key hub for gut–brain communication [Citation9], influencing host metabolism, hormone secretion, and follicular development, and may contribute to infertility in conditions such as polycystic ovary syndrome, endometriosis, and premature ovarian failure. Modulating the gut microbiota could enhance female fertility [Citation10]. For women, the reproductive tract microbiota deserves special attention. The female reproductive tract is a complex cavitary structure connected to the external environment, which can favour the growth of certain microbes and predispose to a range of gynaecologic diseases [Citation11]. The vagina, a crucial conduit linking the external genitalia to the uterus, harbours a rich microbiota; Lactobacilli, as the dominant vaginal flora, help maintain eubiosis, and their reduction can lead to vaginal dysbiosis [Citation12,Citation13]. Disruption of the vaginal microbiota is a major cause of vaginal inflammation, especially bacterial vaginosis (BV), characterised by a decrease in Lactobacilli and an increase in anaerobes, which over time raises the risks of preterm birth [Citation14], miscarriage, and pelvic inflammatory disease. Moreover, accumulating evidence suggests that Lactobacilli can indirectly or directly contribute to cervical cancer prevention, and there is a link between the vaginal microbiome and HPV-driven cervical carcinogenesis [Citation15]. Additionally, vaginal bacteria can ascend into the uterus and affect the microbiota of the upper reproductive tract. While the upper genital tract was traditionally regarded as relatively sterile, accumulating evidence in recent years has demonstrated that the uterine microbiome plays a critical role in female reproduction [Citation16,Citation17]. Currently, numerous studies are investigating the association between microorganisms and uterine disorders such as adenomyosis, suggesting that the microbiota may represent an important factor in the pathogenesis of adenomyosis. Changes of microbiota in adenomyosis patients Microbiota is closely linked to human health. With the development of genomics and high-throughput sequencing technologies, an increasing number of studies have identified changes in the microbiota across different sites in adenomyosis, while also highlighting the potential roles of certain specific microbial biomarkers in the disease (). Vaginal microbiota The vaginal microbiota is dynamic and influenced by various factors [Citation25]. Based on community composition and abundance, five major vaginal Community State Types (CSTs) have been described: CST-I (Lactobacillus crispatus), CST-II (Lactobacillus gasseri), CST-III (Lactobacillus iners), CST-V (Lactobacillus jensenii), with CST-IV exhibiting higher diversity and dominated by Anaerobes and lower Lactobacillus abundance [Citation26]. Collecting vaginal microbiota is relatively straightforward and can serve as an important indicator for monitoring vaginal and uterine health [Citation16]. Multiple studies have reported differences in the vaginal microbiota between women with adenomyosis and healthy controls. For example, Kunaseth et al. collected vaginal swab samples from 40 women with adenomyosis and 40 without (controls) and performed DNA extraction followed by 16S rRNA gene sequencing and data analysis. They found that Lactobacillus was the most abundant genus in both groups. Alpha diversity, as measured by the Chao1 index, revealed higher vaginal microbiota richness in the adenomyosis group, with prominent taxa including Alloscardovia, Oscillospirales, Ruminococcaceae, UCG-002, Oscillospiraceae, Enhydrobacter, Megamonas, Moraxellaceae, Subdoligranulum, Selenomonadaceae, and Faecalibacterium; no significant differences were observed in other alpha diversity indices or beta diversity. Moreover, the two groups showed clear differences in vaginal CSTs, with the adenomyosis group predominantly CST-III and CST-IV, while the control group was mainly CST-IV [Citation18]. This study linked microbial richness with adenomyosis but only assessed vaginal microbiome features in women with and without adenomyosis, highlighting the need for additional omics approaches to clarify the mechanisms underlying these differences. In another study, associations between the vaginal microbiota and adenomyosis were also observed, though not identical to Kunaseth et al. Alpha diversity did not differ significantly, but beta diversity analyses revealed significant differences in vaginal microbiota composition between women with adenomyosis and healthy controls. Notably, there were also differences in microbiota features between patients with internal vs external adenomyosis phenotypes, highlighting the potential role of the microbiota in the adenomyosis background and warranting further investigation to understand the implications of these differences [Citation19]. Pan et al. analysed vaginal samples from 43 women with adenomyosis and 40 healthy controls using 16S rRNA sequencing, and similarly found differences in species abundance between groups. Lactobacillus was the dominant genus in both groups, but Gardnerella abundance was significantly lower in the adenomyosis group. Pan et al. also observed variations in vaginal microbiota across different menstrual phases, suggesting the potential to identify specific biomarkers within a limited scope and to provide more accurate, objective, and individualised diagnostic and treatment assessment for patients with adenomyosis [Citation20]. Although these findings collectively support a close association between the vaginal microbiota and the development of adenomyosis, most studies are limited by small sample sizes. Larger clinical cohorts and multidisciplinary research are therefore required to further elucidate the mechanisms underlying these associations, which will be critical for future clinical application. Endometrial microbiota Endometrial microbiota constitute a unique, low-biomass, and dynamic ecosystem, with microbial composition and function closely linked to female reproductive health [Citation27]. In a preliminary analysis, researchers sequenced the 16S rRNA gene from endometrial samples of 21 women with pathologically confirmed adenomyosis who underwent laparoscopic hysterectomy and 17 women without the disease. Using linear discriminant analysis effect size (LEfSe), they found that endometrial microbial abundance was significantly reduced in the adenomyosis group, with Citrobacter freundii, Prevotella copri, and Burkholderia cepacia posited as potential pathogenic microbial taxa associated with adenomyosis. Subsequently, PICRUSt was used to predict the functional potential of the endometrial microbiota in the two groups, revealing differences in pathways related to information processing and metabolic regulation. Notably, protein export, glycolysis/metabolism, and metabolism of alanine, aspartate, and glutamate were upregulated in the adenomyosis group [Citation21]. However, the sample size in this study was small, warranting validation in a larger cohort. In contrast to Lin et al., Valdés-Bango et al. employed the same methodology and did not observe significant differences in alpha or beta diversity of the endometrial microbiota between groups; however, LEfSe analysis indicated significant differences in endometrial bacterial abundance between groups. Ruminococcaceae and Actinomyces were significantly enriched in the adenomyosis group, whereas Ligilactobacillus, Lacticaseibacillus, and Fastidiosipila were more abundant in controls [Citation19]. While current studies have identified associations between the endometrial microbiota and adenomyosis, causal relationships remain scarce, as reproductive tract microbiota are influenced by numerous factors that complicate causal inference. To address this, Li et al. employed 16S rRNA sequencing to characterise representative endometrial microbiota in both groups and then conducted in vitro co-culture experiments to validate the complex interactions between microbes and adenomyosis [Citation22]. Gut microbiota Gut microbiota and the development of diseases have long been a focal point of research, but studies on the relationship between uterine adenomyosis and the gut microbiota are relatively scarce. In an animal model study, researchers conducted a first analysis of changes in the gut microbiota in adenomyosis. They found that the gut microbial community of adenomyosis mice underwent compositional shifts. While α-diversity and β-diversity showed no significant differences, the relative abundances of bacteria at the phylum and genus levels differed between groups. Compared with controls, the adenomyosis group had an increased ratio of the Firmicutes/Bacteroidota phyla and a higher relative abundance of Lactobacillus. Additionally, 60 differential metabolites were identified in the gut, with a notable decrease in progesterone among gut metabolites, which suggests a potential role in the pathogenesis of adenomyosis; microbial alterations may contribute to the regulation of these metabolites [Citation23]. This study complemented 16S rRNA sequencing with faecal metabolomics, providing new insights into pathogenesis from a different angle, but its reliance on a mouse model and lack of parallel human clinical samples limit the generalisability to human disease and render the conclusions less comprehensive. Valdés-Bango et al. were the first to analyse the gut microbiota using faecal samples from women with adenomyosis. Unlike the mouse study, they observed a significant reduction in gut microbiota diversity in adenomyosis patients. Beta-diversity analyses indicated distinct microbial community composition between groups, characterised by a decrease in Bifidobacterium and notable enrichment of Rhodospirillales and the genus Ruminococcus gauvreauii [Citation19]. Tang et al. conducted a two-sample Mendelian randomisation analysis to investigate the impact of the gut microbiota on the development of related diseases. The results revealed that four bacterial taxa at the genus level exhibited significant associations. Notably, one genus was found to be associated with adenomyosis, while three genera were linked to infertility caused by adenomyosis. Subsequently, the authors further identified gut microbiota-related single nucleotide polymorphisms (SNPs) at the genus level, with 14 independent SNPs showing a significant association with adenomyosis. This study provides potential evidence for the association between the gut microbiota and adenomyosis. However, since adenomyosis was not designated as the core research object, the study failed to elaborate on the correlation between adenomyosis and the gut microbiota in depth [Citation28]. The above studies have preliminarily revealed characteristic alterations in the gut microbiota of patients with adenomyosis and clarified the potential role of gut metabolites in its pathogenesis. Future research could conduct additional clinical investigations to further explore the potential intrinsic association between differences in gut metabolites and changes in the gut microbiota. Potential mechanisms of the microbiota in the development of adenomyosis Based on current progress in microbiota research on adenomyosis, the microbiota plays an important role in disease development. The following sections will discuss the potential mechanisms of the microbiota in adenomyosis from the perspectives of immune-inflammatory processes and oestrogen signalling (). Immune response and inflammation Adenomyosis patients frequently exhibit a chronic inflammatory state, with inflammation and immune regulation closely linked to disease initiation and progression [Citation29,Citation30]. Bourdon et al. reported significant immune dysregulation in the uterine microenvironment of women with adenomyosis, characterised by increased levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, etc.) and anti-inflammatory signals (IL-10, TGF-β) [Citation31]. There is growing evidence linking the microbiota to adenomyosis, with dysbiosis observed in the uterine microbiota; pathogenic taxa include Gram-negative bacteria such as Rhodospirillales, Citrobacter freundii, Burkholderia cepacia, and Prevotella copri, among others [Citation19,Citation21]. Lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria, acts as a bacterial endotoxin and inflammatory marker and can activate pattern recognition receptors such as Toll-like receptor 4 (TLR4), thereby triggering the NF-κB signalling pathway. LPS plays a pivotal role in initiating pro-inflammatory responses, modulating immune responses, promoting angiogenesis, and stimulating growth factor secretion [Citation32]. Consequently, microbial dysbiosis may lead to elevated inflammatory cytokines and promote inflammatory infiltrates, hyperplasia, and neovascularization in adenomyosis. Moreover, LPS can stimulate abundant production of inflammatory mediators by peritoneal endometrial stromal cells and upregulate the expression of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2), with increased prostaglandins directly contributing to pelvic pain and dysmenorrhoea [Citation33]. Another study found that patients with chronic pelvic pain (CPP) associated with endometriosis/adenomyosis (EM/AM) exhibit higher alpha diversity of the vaginal microbiota. However, it remains unclear whether this increased microbial richness is a cause or a consequence of the disease. It is worth noting that the research subjects included both patients with endometriosis and those with adenomyosis, rather than an independent study focused solely on adenomyosis [Citation24]. Adenomyosis is associated with marked immune regulatory abnormalities in the ectopic endometrium, including upregulation of Tim-3/Gal-9 (T cell immunoglobulin and mucin domain 3/galectin-9) and differential RNA methylation [Citation34]. LPS can activate inflammatory pathways and regulate immune responses, suggesting that the microbiota may influence Tim-3/Gal-9–mediated immune suppression through specific mechanisms, potentially allowing persistent infection and disrupting the endometrial microenvironment, thereby contributing to disease pathogenesis. Additionally, expression of stimulator of interferon genes (STING) is significantly increased in the endometrium of adenomyosis patients; as an inducer of type I interferons, this finding implies that host innate immune responses participate in disease progression [Citation35], and microbiota diversity changes may be a key trigger for initiating local endometrial innate immunity. In the future, further clinical research and mechanism verification specifically targeting adenomyosis can be conducted. The specific molecular mechanism of the microbial-inflammation axis in the development and progression of the disease can be clarified, and ways to regulate the microbiota and immune status can be explored to provide new prevention and treatment strategies and targets for adenomyosis. The microbiome and oestrogen Adenomyosis is an oestrogen-dependent gynaecological disease, and its pathogenesis is closely related to abnormalities in oestrogen metabolism and signalling pathways [Citation36]. In the reproductive tract, oestrogen can help maintain vaginal acidic conditions and the abundance of Lactobacillus, thereby protecting the reproductive tract from pathogenic microbes [Citation37,Citation38]. Meanwhile, the microbiota can influence oestrogen metabolism, circulation, and activity through multiple mechanisms, potentially affecting the initiation and progression of disease [Citation39]. The female reproductive tract microbiota is susceptible to age and systemic physiological changes, and studies have shown differences in vaginal microbiota between women with adenomyosis and healthy controls across the menstrual cycle, particularly during the luteal phase [Citation20]. Notably, an animal study reported reduced progesterone levels in the gut metabolic profile of mice with adenomyosis [Citation23]. Oestrogen is a key promoter of endometrial lesion growth and progression, while progesterone is the principal regulator that tightly controls oestrogen action. These results suggest that there may be an intrinsic connection between abnormal oestrogen levels and the dysbiosis of the gut microbiota associated with adenomyosis. The gut microbiota, as a mature endocrine organ, plays a pivotal role in stabilising circulating oestrogen levels [Citation40]. It can participate in the intestinal-portal circulation of oestrogen by secreting metabolic enzymes such as β-glucosidase, regulate the activation level of oestrogen in the circulation, thereby affecting the endocrine homoeostasis of the host, and may be associated with the occurrence and development of female reproductive-related diseases [Citation41]. Recent studies have shown that oral administration of probiotics with β-glucosidase activity can modulate the body's oestrogen levels. The oestrogen levels of subjects who received the probiotic intervention differed from those in the control group [Citation42]. Clinical studies have shown that the microbiota in the reproductive tracts or intestines of patients with adenomyosis exhibit characteristic changes, among which the abundance of Lactobacillus is particularly significant. Lactobacillus can harbour a functional gene encoding β-glucosidase, which converts bound oestrogen to free oestrogen, thereby affecting the body's overall oestrogen balance [Citation43,Citation44]. These observations may suggest that the interaction between microorganisms and oestrogen is associated with the development of adenomyosis. However, the current evidence supporting the direct role of microbe-induced high oestrogen in adenomyosis is limited, and most of it is indirect and still requires further research for verification. Application prospects of microbiota in adenomyosis Treatment Probiotics Probiotics refer to live microorganisms that confer health benefits to the host when administered in adequate amounts. They mainly consist of lactic acid bacteria and Bifidobacteria, and can modulate the host’s commensal microbiota, regulate immune responses, and strengthen intestinal barrier function. Probiotics and related preparations have shown promising potential in the prevention and treatment of various diseases [Citation45,Citation46]. As live microorganisms, probiotics can modulate the composition and abundance of the intestinal microbiota, restore gut ecological balance, and promote host health. In a comprehensive study, Lactobacillus was reported to downregulate the expression of inflammatory proteins (TLR, MyD88, p65/p-p65), inhibit pathogenic bacteria, and alleviate inflammation in mice [Citation47]. Lactobacillus is the dominant bacterium in patients with adenomyosis, and the application value of its related probiotics in the treatment of this disease deserves further attention. In the future, probiotics targeting Lactobacillus may become a new direction for adenomyosis treatment. Microbiota transplantation In recent years, the therapeutic potential of the microbiome in improving human health has become a research focus. Faecal microbiota transplantation (FMT) is a treatment that delivers the microbial community from healthy donors to patients, thereby restoring or reconstructing the microbial balance of recipients [Citation48,Citation49]. Microbiome transplantation therapy is primarily based on faecal microbiota transplantation (FMT), which is widely used in the treatment of intestinal diseases, particularly for Clostridioides difficile infection, for which it exhibits high efficacy [Citation50]. FMT can restore microbial balance by directly inhibiting intestinal pathogens, activating the mucosal immune system, and regulating the gut microbial ecosystem dynamically via the microbiota–gut–brain axis [Citation51,Citation52]. In the research on animal models, it was found that FMT can improve the microbial flora, indicating its potential application in the treatment of female reproductive diseases [Citation53,Citation54]. Patients with adenomyosis frequently display dysbiosis of both the gut and vaginal microbiota. However, clinical studies investigating microbiota transplantation for adenomyosis remain lacking, and targeted research frameworks and translational evidence are currently insufficient. Therefore, further clinical trials are warranted to evaluate the efficacy of microbiota transplantation for adenomyosis and to provide a scientific basis for its clinical translation. Drugs targeting the microbiota The regulatory role of the microbiota in health and disease has been widely recognised, and researchers are increasingly investigating microbiome-targeted therapies to enhance treatment efficacy [Citation55]. Barone et al. established a mini-intestinal model using an in vitro high-throughput screening platform, identified several microbiome-targeted agents, and demonstrated the potential of drug–microbiome interactions in disease therapy [Citation56]. In oncology, targeting the gut microbiota can also reduce chemotherapy toxicity, improve cancer prognosis, and enhance patient quality of life [Citation57]. Many studies have now demonstrated the potential of the microbiota in the treatment of adenomyosis and identified relevant microbial biomarkers, but further clinical studies are needed to validate these findings. Microbiota and fertility Most patients with adenomyosis suffer from infertility, and the underlying mechanisms are complex. Studies have indicated that reduced endometrial receptivity, implantation failure, and immune abnormalities may contribute to infertility in these patients [Citation58]. Recent studies have demonstrated the potential value of the microbiota in adenomyosis. Dysbiosis can impair the health and function of the reproductive tract and may play a vital role in the pathogenesis of infertility associated with adenomyosis [Citation59]. In the eutopic endometrium of adenomyosis patients, there is elevated expression of pro-inflammatory cytokines and abnormal expression of decidualization-associated biomarkers, leading to altered endometrial receptivity and impaired implantation, thereby affecting fertility [Citation60]. Moreno et al. identified the presence of specific pathogens in the endometrium and a depletion of Lactobacillus that is associated with impaired reproductive function. The composition of the endometrial microbiome before embryo transfer may serve as a valuable biomarker for predicting reproductive outcomes [Citation17]. Another study reported that vaginal microbiota dysbiosis may also induce endometrial changes and affect embryo transfer outcomes [Citation61]. Microbiota-targeted interventions may provide new avenues for treating infertility associated with adenomyosis. Diagnosis and markers Adenomyosis typically presents with dysmenorrhoea, abnormal uterine bleeding, and uterine enlargement, and its diagnosis often depends on imaging examinations or postoperative pathological confirmation. These limitations may result in misdiagnosis or missed diagnosis, representing a diagnostic challenge, as specific noninvasive diagnostic methods are currently lacking [Citation62]. In recent years, the role of the microbiome in adenomyosis has garnered increasing attention. Studies have identified microbiota alterations at multiple sites in women with adenomyosis, and distinct dominant microbial taxa have been observed during different menstrual phases and at various lesion sites, which may serve as potential microbial biomarkers [Citation20]. In mouse models of adenomyosis, certain gut microbial metabolites have also been proposed as potential markers of lesion proliferation [Citation23]. Moreover, specific microbial biomarkers for adenomyosis may complement routine clinical diagnostic indicators. Cancer antigen 125 (CA-125) is a widely used auxiliary diagnostic marker for adenomyosis in clinical practice. In studies of endometriosis/adenomyosis-associated chronic pelvic pain, potential pathogenic bacteria and prospective biomarkers have been identified. For instance, a combined panel of Clostridium disporicum, Lactobacillus reuteri, and serum CA-125 may facilitate early differential diagnosis [Citation24]. Although the potential value of microbial biomarkers in adenomyosis has been preliminarily demonstrated, adenomyosis-specific clinical validation remains lacking, and the majority of studies are limited to small sample sizes, animal models, or specific ethnic populations. Future research should focus on large-scale, multi-centre clinical trials to evaluate the influence of ethnicity on the human microbiome, facilitate the development of microbial biomarkers into noninvasive diagnostic and screening tools, and enable early diagnosis and intervention for patients with adenomyosis. Methodological limitations in microbiome studies of adenomyosis Currently, microbiomic technologies offer novel insights into exploring the pathogenesis of adenomyosis and identifying microbial biomarkers. Nevertheless, current microbiome research methodologies for uterine adenomyosis still present substantial limitations, which compromise the reliability and clinical translational potential of research findings to some extent. Contamination frequently occurs during the collection of adenomyosis‑related microbiome samples. In particular, the endometrial microbiome is characterised by low microbial biomass and is thus highly vulnerable to interference from environmental bacteria and experimental reagent contaminants during sample collection, transportation, and nucleic acid extraction. This ultimately impairs the accurate screening and evaluation of disease‑associated microbial communities. Meanwhile, no unified standards have been established across studies regarding microbiome sequencing platforms, bioinformatic analysis pipelines, sequencing depth, or taxonomic annotation databases. Such inconsistencies readily lead to discrepancies in microbial community profiling and further limit the reproducibility and cross‑study comparability of research outcomes. Furthermore, various confounding factors—including patient ethnicity, age, menstrual cycle phase, hormone levels, medication history, and concurrent gynaecological disorders—may potentially influence the structure of the relevant microbial communities. This complicates efforts to establish a clear causal relationship between the microbiome and adenomyosis.

Recent studies have increasingly focused on microbiota alterations in patients with adenomyosis, whose pathogenesis is considered closely associated with immune‑inflammatory responses and abnormal oestrogen levels. However, the causal relationships among these factors remain unclear, and most existing evidence is derived from small‑sample studies and animal experiments, with a lack of large‑scale, multicenter clinical validation. The microbiota is susceptible to multiple factors, including age, body weight, menstrual cycle phase, ethnicity, and geographic origin. Variations in sampling and detection methodologies may also confound microbiome analyses. Currently, evidence supporting the efficacy and safety of probiotics, microbiota transplantation, and targeted microbiome interventions remains limited due to insufficient basic and clinical data, highlighting the necessity for further investigation prior to clinical implementation. Therefore, future research should prioritise standardised experimental designs, larger sample sizes, and diverse study populations to verify potential causal links between the microbiota and adenomyosis and to elucidate the underlying mechanisms. With advances in genomics and high‑throughput sequencing technologies, further studies may concentrate on identifying microbiome‑based biomarkers for adenomyosis. This could offer new insights for the development of innovative diagnostic and therapeutic strategies involving probiotic interventions, microbiota transplantation, and targeted microbiome modulation. These approaches would not only improve the diagnosis and treatment of adenomyosis but also provide new strategies to enhance fertility in affected patients.

We want to express our gratitude for the drawing materials provided by BioRender. All authors contributed to the article and approved the submitted version. Disclosure statement The authors declare no competing interests. Data availability statement Data sharing is not applicable to this article as no data were created or analysed in this research. Additional information Funding

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