{"paper_id":"34403a6b-4ac7-4f7b-bfa0-db3eb62d9aa9","body_text":"Abstract\nBackground\nThe levonorgestrel-releasing intrauterine system (LNG-IUS) is widely used for adenomyosis, but expulsion and displacement may compromise treatment. We estimated their study-reported cumulative proportions and compared fixed or modified placement with conventional placement.\nMethods\nPubMed, Embase, Web of Science Core Collection, CENTRAL, and Scopus were searched from inception to July 2026. Random-effects models pooled proportions and risk ratios (RRs) with 95% confidence intervals (CIs). Follow-up subgroups, common-time-point sensitivity analyses, and a binomial generalized linear mixed model (GLMM) were examined. Certainty of evidence was assessed using GRADE.\nResults\n30 studies reporting 3,536 participants overall were included. Across 24 studies (2,443 participants), the pooled cumulative proportion of reported expulsion was 7.3% (95% CI, 3.7%–11.7%), with substantial heterogeneity (I² = 89.55%) and a 95% prediction interval of 0.0%–34.7%. Proportions were 2.8% (95% CI, 0.8%–5.6%) and 13.6% (95% CI, 6.9%–22.0%) in studies with nominal follow-up of ≤ 12 and > 12 months, respectively (P = 0.004 for the subgroup difference). Separate analyses at exact 6- and 12-month endpoints yielded approximately 3% and 4%, respectively, in different sets of studies. The GLMM estimate for reported expulsion was 5.8% (95% CI, 3.1%–10.4%). Across seven studies (329 participants), the pooled reported-displacement proportion was 0.8% (95% CI, 0.0%–2.5%). Exploratory comparisons associated fixed or modified placement with less reported expulsion (two nonrandomized studies; RR, 0.12; 95% CI, 0.03–0.49) and fewer displacement-or-expulsion composite events (one randomized and one nonrandomized study; RR, 0.28; 95% CI, 0.15–0.54). Certainty was very low for the graded outcomes; no single GRADE rating was assigned to the mixed-design pooled composite estimate.\nConclusions\nStudy-reported LNG-IUS expulsion and displacement occur in women with adenomyosis, but heterogeneity in follow-up, outcome definitions, and ascertainment, together with very low-certainty evidence, limits interpretation. The low reported frequency of displacement may underestimate positional abnormalities because asymptomatic cases can be missed without systematic imaging. Exploratory comparisons do not establish a clinical benefit of fixed or modified placement or support its routine use.\nSimilar content being viewed by others\nAcknowledgements\nNot applicable.\nFunding\nThis study was supported by the 2026 Traditional Chinese Medicine Innovation Capacity Project of the Affiliated Hospital of Zunyi Medical and Pharmaceutical College (Zunyi Academy of Chinese Medicine), entitled “Construction of the Core Academic System of National Traditional Chinese Medicine Master He Chengyao’s ‘Nourishing Essence to Promote Conception’ Theory and Its Application in Standardized Diagnosis and Treatment Protocols for Female Infertility and Adenomyosis.” The funder had no role in the study design, data collection, data analysis, interpretation of the results, preparation of the manuscript, or decision to submit the manuscript for publication.\nAuthor information\nAuthors and Affiliations\nCorresponding author\nEthics declarations\nEthics approval and consent to participate\nNot applicable. This systematic review and meta-analysis used data from previously published studies and did not involve individual-level patient data or direct contact with human participants.\nConsent for publication\nNot applicable.\nCompeting interests\nThe authors declare no competing interests.\nAdditional information\nPublisher’s note\nSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.\nSupplementary Information\nRights and permissions\nOpen Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.\nAbout this article\nCite this article\nXie, L., Zhu, G., Zou, K. et al. Reported expulsion and displacement of the levonorgestrel-releasing intrauterine system in women with adenomyosis: a systematic review and meta-analysis. BMC Women's Health (2026). https://doi.org/10.1186/s12905-026-05045-2\nReceived:\nAccepted:\nPublished:\nDOI: https://doi.org/10.1186/s12905-026-05045-2","source_license":"CC0","license_restricted":false}