Adenomyosis is a common gynecological condition that can cause menstrual pain, heavy menstrual bleeding, anemia, and reduced quality of life. The levonorgestrel-releasing intrauterine system is commonly used as a conservative treatment, but displacement or expulsion of the device may occur, especially in patients with an enlarged uterus or a deep uterine cavity.

This study evaluated whether combining an Indomethacin-GyneFix intrauterine device with a levonorgestrel-releasing intrauterine system could improve device stability in patients with adenomyosis. Eligible participants were randomly assigned to receive GyneFix IUD plus LNG-IUS, ring IUD plus LNG-IUS, or LNG-IUS alone. Participants were followed for 6 months after device placement. The main outcome was device displacement or expulsion at 6 months. Other outcomes included menstrual pain, menstrual blood loss, uterine volume, hemoglobin, CA125, adverse events, and treatment acceptance.

This was a single-center, prospective, parallel-group, randomized controlled trial conducted at Wenzhou People's Hospital in patients with adenomyosis. The study was designed to compare three intrauterine treatment strategies for improving the stability of a levonorgestrel-releasing intrauterine system in patients with different uterine cavity depths.

Eligible patients were women diagnosed with adenomyosis who had no current desire for pregnancy, had no contraindications to intrauterine device placement, and were able to complete scheduled follow-up. After written informed consent was obtained, participants were randomly assigned in a 1:1:1 ratio to one of three groups: GyneFix IUD plus LNG-IUS, ring IUD plus LNG-IUS, or LNG-IUS alone.

In the GyneFix IUD plus LNG-IUS group, the Indomethacin-GyneFix IUD was used as an anchoring device to stabilize the LNG-IUS. The anchoring knot of the GyneFix IUD was placed in the uterine fundal myometrium under ultrasound guidance, allowing the LNG-IUS to remain suspended and stabilized within the uterine cavity. In the ring IUD plus LNG-IUS group, a ring IUD was placed together with the LNG-IUS to provide passive mechanical support. In the LNG-IUS-alone group, the LNG-IUS was inserted according to the standard procedure.

All procedures were performed under real-time ultrasound guidance by experienced gynecologists. Participants were followed at approximately 1 month, 3 months, and 6 months after device placement. Follow-up assessments included symptom evaluation, gynecological examination, ultrasound assessment of device position and uterine parameters, laboratory testing, adverse event monitoring, and treatment acceptance assessment.

The primary outcome was intrauterine device displacement or expulsion at 6 months. Secondary outcomes included changes in dysmenorrhea measured by visual analogue scale, menstrual blood loss measured by pictorial blood loss assessment chart, uterine volume, hemoglobin, serum CA125, adverse events, and patient acceptance. A subgroup analysis was planned according to uterine cavity depth.

Inclusion Criteria:

• Female patients aged 20 to 55 years.
• Diagnosed with adenomyosis by transvaginal ultrasound.
• No current desire for pregnancy and willing to receive conservative intrauterine treatment.
• No contraindications to intrauterine device placement.
• Able to understand the study procedures and voluntarily provide written informed consent.
• Able and willing to comply with scheduled follow-up visits and study assessments.

Exclusion Criteria:

• Pregnancy or suspected pregnancy.
• Concurrent malignant tumor of the reproductive system.
• Severe cervical lesions or uterine malformations.
• Severe coagulation disorder.
• Severe hepatic or renal insufficiency.
• Known hypersensitivity to levonorgestrel, copper, indomethacin, or related device components.
• Uncontrolled pelvic inflammatory disease or untreated vaginal infection.
• Uterine prolapse grade II or higher.
• Any condition judged by the investigator to make intrauterine device placement unsuitable.
• Inability to complete follow-up or incomplete key clinical data.
• Withdrawal of consent during the study.

De-identified individual participant data underlying the results reported in this study may be made available from the corresponding author upon reasonable request, after publication and subject to approval by the study investigators and applicable institutional requirements.

Beginning after publication with no fixed end date.

Researchers with a scientifically sound proposal may request access to de-identified data. Requests will be reviewed by the corresponding author and study investigators, and data sharing will be subject to ethics, privacy, and institutional requirements.

Complete masking of participants and treating gynecologists was not fully feasible because the interventions involved different intrauterine device configurations and placement procedures. Postoperative outcome assessors who collected follow-up symptom assessments, satisfaction questionnaires, and medical record data were blinded to treatment allocation. Statisticians analyzed coded group labels. Ultrasound physicians were not masked because the device type was identifiable on imaging.