GyneFix levonorgestrel-releasing intrauterine system for Chinese patients: a preliminary retrospective self-controlled observational study

Abstract

Background

Device expulsion is a common complication of the levonorgestrel-releasing intrauterine system (LNG-IUS), with a higher incidence among high-risk patients presenting with enlarged uterine cavities, cervical laxity or menorrhagia. At present, no commercially available frameless LNG-IUS is marketed in mainland China, leaving these high-risk patients without effective clinical interventions.

Objectives

This study describes the assembly procedures and clinical application of a modified frameless LNG-IUS based on the GyneFix anchoring system (GyneFix-LNG-IUS), and the intrauterine retention performance is preliminarily assessed alongside its capacity to reduce expulsion risk.

Methods

This was a retrospective, self-controlled, observational prognostic study. A total of 15 consecutive cases were included. All included cases had a documented history of conventional LNG-IUS expulsion and multiple high-risk factors for expulsion, including enlarged uterine cavities, menorrhagia and cervical laxity. The modified device was assembled using the GyneFix anchoring component and a standard LNG-IUS, and inserted under hysteroscopic guidance. The 12-month device retention rate and its corresponding 95% confidence interval were calculated.

Results

All insertions of GyneFix-LNG-IUS were completed successfully in a single attempt, and no intra-operative or post-operative complications were recorded. Gynaecological ultrasound data acquired at 12 months or longer after placement were collected for all cases. Ultrasonographic examinations confirmed that all devices were positioned within the uterine fundus, with no signs of downward displacement or expulsion observed. The 12-month retention rate was 100% (95% CI: 78.2%–100%).

Conclusions

Based on the limited data from this small cohort, the modified GyneFix-LNG-IUS features simple assembly and smooth intrauterine insertion. Preliminary findings indicate that this device may reduce expulsion risk among patients prone to conventional LNG-IUS loss. It may serve as a viable clinical alternative in settings without access to commercial frameless LNG-IUS.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s12905-026-04649-y.

Background

The levonorgestrel-releasing intrauterine system (LNG-IUS) is a commonly used contraceptive device in clinical practice, and it also delivers definite therapeutic effects for patients with dysmenorrhoea, abnormal uterine bleeding, menorrhagia, pelvic endometriosis or uterine adenomyosis [1–15]. For high-risk populations, enlarged uterine cavities, cervical laxity and severe menorrhagia are the main predisposing factors for the downward displacement and expulsion of the intrauterine system [11–15]. At present, no frameless LNG-IUS has obtained marketing approval for routine clinical use across mainland China, meaning that viable treatment options to mitigate expulsion risk remain limited for this vulnerable high-risk patient cohort.

To address this clinical challenge and explore clinical solutions for reducing the risk of LNG-IUS expulsion in high-risk patients, clinicians have combined GyneFix anchoring devices with conventional LNG-IUS to develop a new type of frameless LNG-IUS for real-world clinical application. This composite device is named GyneFix-LNG-IUS, which retains the structural stability of the GyneFix anchoring system and possesses the drug release properties of LNG-IUS. This study aims to elaborate on the assembly methods and clinical application of GyneFix-LNG-IUS, present its preliminary safety outcomes, and primarily evaluate its efficacy in preventing device expulsion among high-risk patients.

Methods

This is a retrospective, observational, self-controlled prognostic study conducted on consecutive clinical cases. All diagnosis and treatment regimens as well as follow-up plans were formulated by attending physicians after full communication with patients according to individual clinical conditions. No dedicated research protocol was established prior to treatment initiation, and data analysis was performed after the completion of all clinical work.

A total of 15 consecutive cases receiving GyneFix-LNG-IUS insertion at the institution between February and October 2024 were included in this analysis. No case screening was conducted, and no selection bias was present. All included cases met the following inclusion criteria: (1) No future fertility requirements; (2) A confirmed diagnosis of at least one of the following conditions: dysmenorrhoea, abnormal uterine bleeding, menorrhagia, pelvic endometriosis or uterine adenomyosis; (3) Presence of at least one high-risk factor for the downward displacement and expulsion of LNG-IUS, including an enlarged uterine cavity (uterine depth > 8 cm), menorrhagia prone to device expulsion, or cervical laxity; (4) A documented history of at least one episode of LNG-IUS expulsion; (5) Absence of contraindications to intrauterine device (IUD) insertion, including pregnancy, acute pelvic inflammatory disease, malignant diseases of the reproductive system and severe systemic disorders.

GyneFix-LNG-IUS is assembled from a GeneFlex frameless anchored IUD (model IN/S; manufactured by Tianjin Hejie Medical Devices Co., Ltd.) and a standard Mirena LNG-IUS (manufacturer: Bayer Yakuhin, Ltd.). The assembly procedures of GyneFix-LNG-IUS are described as follows. The anchoring structure of the GyneFix IUD is retained while its copper rings are removed (Fig. 1). The tubular body and tail thread of the LNG-IUS are preserved, and its T-shaped frame is excised (Fig. 2). The tail thread of the LNG-IUS is firmly tied to the anchoring structure of the GyneFix IUD to complete the assembly of the modified device (Fig. 3, Supplementary Fig. 1). The assembled device is subsequently loaded into a GyneFix applicator for intrauterine insertion (Fig. 4, Supplementary Fig. 2).

Fig. 1.

The anchoring component of the GyneFix IUD was retained, and the copper rings were removed

Fig. 2.

The tubular column and tail thread of the LNG-IUS were preserved, while the T-shaped frame was excised. The red LNG-IUS depicted is a teaching model

Fig. 3.

The tail thread of the LNG-IUS was securely knotted to the anchoring component of the GyneFix IUD to construct the modified GyneFix-LNG-IUS

Fig. 4.

The assembled GyneFix-LNG-IUS was loaded into the GyneFix applicator in preparation for intrauterine insertion

All component assembly procedures were completed under strict aseptic conditions. The assembled device was inserted immediately without secondary sterilisation. The surgical procedures for GyneFix-LNG-IUS insertion are consistent with those for conventional GyneFix IUDs. In brief, the device was anchored to the uterine fundus at a depth of 1 cm using a GyneFix applicator. Manual tensile tests were performed before insertion to ensure firm connection between the anchoring knot and the tubular body of the LNG-IUS. No device fracture was observed in any of the cases. The entire assembly and insertion procedures were completed by experienced physicians specialising in IUD management within 20 min. Hysteroscopy was performed on all cases during the insertion procedure. This examination was used to assist device placement and verify the intrauterine position of the device (Fig. 5, Supplementary Video 1; Fig. 6, Supplementary Video 2).

Fig. 5.

Hysteroscopic view of the uterine cavity prior to GyneFix-LNG-IUS insertion, with endometrial trimming performed

Fig. 6.

Hysteroscopic confirmation of secure GyneFix-LNG-IUS placement at the uterine fundus

All cases were advised to return for clinical monitoring at 1, 3, 6 and 12 months after GyneFix-LNG-IUS insertion to assess device position, adverse events and clinical efficacy. In practice, most cases attended clinical monitoring visits according to their personal schedules rather than strictly adhering to the scheduled time points. The primary observational endpoint of this study was set at 12 months after device insertion, and the intrauterine position of GyneFix-LNG-IUS was mainly assessed at this time point. All ultrasonographic examinations were performed by qualified professional gynaecological sonographers who did not participate in device insertion and were blinded to the clinical data of each case, thereby enabling single-blind assessment. Definitions of positional terminology are listed below. Expulsion refers to the complete detachment of the IUD from the uterine cavity. Downward displacement is defined as the shift of the device towards the cervix without complete expulsion. Retention indicates normal device position confirmed by ultrasonography, with the distance between the upper edge of the device and the uterine fundus less than 1 cm.

All statistical analyses were performed using SPSS 26.0 software. The Clopper-Pearson exact method was adopted to calculate the 95% confidence interval for the 12-month retention rate of GyneFix-LNG-IUS.

Results

Insertion procedures for all GyneFix-LNG-IUS devices were completed in a single attempt, with no intra-operative or post-operative complications recorded. Gynaecological ultrasound data acquired at or beyond the 12-month predefined observational endpoint were collected for every case in this study, and all cases completed clinical monitoring without loss to observation.

Ultrasonographic assessments covering this minimum 12-month monitoring threshold revealed that all GyneFix-LNG-IUS devices were sited within the uterine fundus, with no signs of downward displacement or expulsion identified (Fig. 7). The corresponding device retention rate was 100% (95% CI: 78.2%–100%), and stable intrauterine positioning was observed in all included cases. No severe device-related adverse events were documented within this retrospective observational cohort. Combined radiological and clinical evaluation confirmed that uterine device embedment and uterine perforation were absent in all cases. Pre-existing baseline symptoms including dysmenorrhoea, abnormal uterine bleeding and menorrhagia were not reported to have worsened. Symptom relief of varying degrees was described by most cases within the cohort.

Fig. 7.

Transvaginal ultrasound image demonstrating the position of the GyneFix-LNG-IUS within the uterine cavity

Discussion

Most conventionally used IUDs adopt framed designs such as T-shaped, O-shaped and cavity-adapted structures, which are fixed inside the uterine cavity by their frames. However, framed IUDs cannot be firmly anchored to the uterine wall, so the risks of downward displacement and expulsion are present. Such risks are further increased in patients with abnormal uterine morphology or function. Frameless IUDs are anchored to the uterine fundus and have been applied in clinical practice since the 1980s [16, 17]. The GyneFix IUD is a representative anchored frameless device with proven contraceptive efficacy [18–21]. It has been shown to reduce the incidence of IUD displacement and expulsion and is widely used across the world.

The American College of Obstetricians and Gynaecologists recognises the 2010 United States Medical Eligibility Criteria for Contraceptive Use and encourages clinicians to follow these guidelines. LNG-IUS is recommended as a preferred contraceptive method, especially for women with dysmenorrhoea, abnormal uterine bleeding, menorrhagia, pelvic endometriosis or uterine adenomyosis [4–7]. The Obstetrics and Gynaecology Society of China also recognises LNG-IUS for its reliable contraceptive effects, definite therapeutic outcomes, cost-effectiveness and clinical convenience. Nevertheless, downward displacement and expulsion of LNG-IUS still occur in some patients due to enlarged uterine cavities, cervical laxity or menorrhagia, which may lead to contraceptive failure and reduced intrauterine therapeutic effects [11–14].

Frameless LNG-IUS with anchoring structures (FibroPlant LNG-IUS) have undergone clinical research and application in several Western countries. This device is designed for anchorage to the uterine fundus (Fig. 8). Its therapeutic effects are comparable to those of conventional T-shaped LNG-IUS, and it helps reduce the risks of device downward displacement and expulsion [22–25]. Regrettably, this type of device has not been approved for clinical use in mainland China, which creates a gap in treatment options for patients at a high risk of device expulsion.

Fig. 8.

Comparative illustration of the conventional framed LNG-IUS (left) and the FibroPlant-LNG IUS (right) in a uterine model, showing their respective configurations following insertion

Chinese gynaecologists have explored multiple strategies to tackle the clinical problem of LNG-IUS displacement and expulsion [26–41]. For example, continuous administration of gonadotrophin-releasing hormone agonists has been used to reduce uterine volume and induce amenorrhoea before LNG-IUS insertion to lower the risk of expulsion. Another approach involves the concurrent insertion of a metal IUD and an LNG-IUS to achieve mutual interlocking inside the uterine cavity and prevent displacement. However, the above two approaches have limited effects on resolving device displacement and expulsion and have been gradually phased out in clinical practice. Some gynaecologists have attempted to suture LNG-IUS to the uterine cavity under hysteroscopic guidance [30–41], but such procedures are technically demanding and difficult to popularise. The above attempts reflect the innovative practices of clinicians to meet unmet clinical needs as well as the practical challenges encountered in clinical work.

GyneFix-LNG-IUS has been adopted to meet unmet clinical demands. This retrospective, observational, self-controlled prognostic analysis included high-risk cases with a history of LNG-IUS expulsion to summarise the retention outcomes of this modified device. The collected data show that GyneFix-LNG-IUS features simple assembly and smooth insertion. Stable retention was observed throughout the clinical monitoring period of 12 months or longer (retention rate: 100%, 95% CI: 78.2%–100%), which preliminarily indicated favourable intrauterine retention trends among high-risk cases. This modified device can serve as a clinical alternative in regions where commercial frameless LNG-IUS is unavailable.

Perioperative hysteroscopy acts as an effective auxiliary examination for patients at a high risk of IUD displacement and expulsion, particularly those with abnormal uterine morphology or function. Preoperative hysteroscopic assessment allows evaluation of uterine cavity morphology and management of endometrial hyperplasia, which facilitates firm anchorage of GyneFix-LNG-IUS to the uterine fundus. Repeat hysteroscopy after device insertion is used to confirm accurate placement and enable early detection and management of anchorage abnormalities or uterine perforation. A small-calibre hysteroscope was used in this study. Cervical dilatation to a large extent, anaesthesia and electrosurgical operations were not required, so the risks of infection and uterine perforation were extremely low. However, this examination increases medical costs to a certain extent. With the continuous improvement of clinical techniques for frameless IUD insertion, routine combined hysteroscopy will no longer be required for most patients in the future.

This single‑centre retrospective analysis carries unavoidable potential selection bias. The relatively small sample size limits the generalisability of observed outcomes and prevents extrapolation of these findings to wider patient populations. Clinical monitoring within this work was confined to a 12-month timeframe; long-term safety profiles and sustained device performance remain to be validated via prolonged clinical observation. Furthermore, intrauterine retention of the modified GyneFix-LNG-IUS was the sole primary endpoint. No quantitative analyses of symptomatic improvements in dysmenorrhoea, abnormal uterine bleeding or menorrhagia were performed, nor was contraceptive efficacy formally assessed. Standardised comparisons against alternative regimens including hysteroscopic suture fixation of LNG-IUS were also omitted. These constitute the core limitations of this preliminary analysis. While the retention outcomes recorded in this high-risk retrospective cohort deliver encouraging preliminary observational signals, all findings must be interpreted with caution. Larger multi-centre prospective observational analyses are needed to corroborate these early clinical trends.

Conclusions

Based on data from this small sample, the modified frameless GyneFix-LNG-IUS features straightforward assembly and smooth insertion. Favourable preliminary intrauterine retention trends were seen in patients with a prior high risk of device expulsion. This modified real-world clinical approach may serve as a viable alternative in settings without access to commercial frameless LNG-IUS. Further clinical data from larger cohorts and longer clinical monitoring periods are needed to confirm the safety and performance of this configuration across broader patient groups.

Abbreviations

LNG-IUS

Levonorgestrel-releasing intrauterine system

IUD(s)

Intrauterine device(s)

GyneFix-LNG-IUS

GyneFix anchoring system-based levonorgestrel-releasing intrauterine system

Authors' contributions

Y.W. contributed to study conceptualization, data curation, and original draft writing. L.Z. was responsible for the development of the study methodology. X.W. conducted formal data analysis and clinical investigation. H.Y. provided study resources and materials. J,C. performed data visualization. J.G. oversaw data validation, manuscript review and editing, project supervision, and overall project administration. All authors have read and approved the final manuscript prior to submission.

Funding

This study was supported by the Bengbu Central Hospital Research Project (Grant No. 2025bbsy28). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Data availability

The datasets generated and analysed during the current study are not publicly available due to the protection of patient privacy and institutional data governance policies, but are available from the corresponding author on reasonable formal request in compliance with standard research ethical guidelines. All study findings supporting the conclusions are fully presented within the manuscript.

Declarations

Ethics approval and consent to participate

This retrospective observational study was approved by the Institutional Review Board of The Third People’s Hospital of Bengbu (No. 2024-K56), covering the off-label assembly, placement, and retrospective analysis of this modified intrauterine configuration. Devices were assembled from legally marketed approved components for compassionate clinical care, not new manufacture. All cases provided written informed consent, with full awareness that the intrauterine device utilised was a modified, non-commercial configuration assembled from two commercially approved components for this exploratory clinical observational study. All procedures followed the Declaration of Helsinki. This non-interventional retrospective observational prognostic analysis was registered at ClinicalTrials.gov (NCT07518693, initial public release: 01 April 2026).

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.