OBJECTIVES: To estimate the effectiveness of a postoperative levonorgestrel-releasing intrauterine system for relieving pelvic pain in patients with endometriosis.

METHODS: A double-blind randomized controlled trial was conducted in 55 patients with endometriosis and moderate-to-severe dysmenorrhea (visual analog scale, greater than 50 mm) undergoing laparoscopic conservative surgery. After surgery, patients were randomized to a levonorgestrel-releasing intrauterine system (n=28) or expectant management (n=27) group. Primary outcome was the change of dysmenorrhea visual analog scale. Secondary outcomes included changes of pelvic pain and dyspareunia visual analog scale, Short Form-36 score, and adverse effects.

RESULTS: The two groups were comparable in age, body mass index, parity, and baseline pain scores. At 12 months, the levonorgestrel-releasing intrauterine system group had a significantly lower median value of dysmenorrhea and noncyclic pelvic pain score. Compared with the control group, the levonorgestrel-releasing intrauterine system group had greater reduction in dysmenorrhea visual analog scale (-81.0 compared with -50.0 mm, P=.006) and pelvic pain visual analog scale (-48.5 compared with -22.0 mm, P=.038) but a comparable reduction in dyspareunia visual analog scale (-15.0 compared with -19.0 mm, P=.831). Two patients in levonorgestrel-releasing intrauterine system group (7.4%) and nine in the expectant management group (39.1%) had recurrent dysmenorrhea within 1 year postoperatively (P=.014). Number-needed-to-treat to prevent one case with recurrent dysmenorrhea within the first year was three cases. The Short Form-36 scores improved in the levonorgestrel-releasing intrauterine system group but did not change in the expectant management group. There was no serious adverse event during the study period.

CONCLUSION: The levonorgestrel-releasing intrauterine system is effective and well accepted for long-term therapy after conservative surgery for patients with moderate to severe pain related to endometriosis. It can improve the patient's quality of life, including physical and mental health.