Outcome measures
The primary outcome measure was proportion of patients with a reduction of postmenstrual spotting of more than 2 days at each follow-up point and without the need for additional therapy, using the ITT analyses, we called it the effective rate. If an IUD was removed because of symptoms or if additional therapies were applied, we considered this as a failure. We defined postmenstrual spotting as brownish discharge for more than two days at the end of the menstruation, with a total duration (menstruation and spotting) of more than seven days, or intermenstrual blood loss that starts after the end of the menstruation.3 Menstrual characteristics were self-recorded in a menstruation diary at 3, 6, 9 and 12 months after inclusion and uploaded in an electronic data system (Figure S2).
Secondary outcome measures were: menstrual characteristics (eg, duration of menstruation, total days of blood loss per month, presence of spotting, amenorrhea was defined as no menstruation/irregular bleeding or spotting for at least 3 m­onths19 and need for treatment because of gynecological complaints); direct medical costs (including the costs of preoperative examination, medical consumption and the surgery); Complications and side effects were evaluated using digital questionaires, these included questions on urinary tract injury, fever, infection, breast pain, pelvic pain, emotional wings, depression, weight changes and acne;
MRI measurements at baseline were: presence of a niche (depth of ≥ 2mm), width, depth, length and thickness of residual myometrium (TRM), uterine position. Measurements were performed in line with previous studies,17, 20 and as recommended by a group of international experts (see Figure S3).21