When ovarian endometrioma coexist with adenomyosis, the risk of postoperative recurrence increased. How is the effect of levonorgestrel-releasing intrauterine system (LNG-IUS) on symptomatic recurrence for those patients was unknown.

This study retrospectively analyzed 119 women with coexistent endometrioma and diffuse adenomyosis who received laparoscopic excision of pelvic endometriosis from January 2009 to April 2013. Women were categorized into two groups: intervention group with LNG-IUS and control group with expectant observation after surgery. Data were compared in terms of preoperative history, laboratory and intraoperative findings, and clinical outcomes during follow-up, including pain regression, changes in uterine volume and recurrence.

During a median 79 months (range, 6–107) of follow-up, patients with LNG-IUS experienced a significantly lower symptomatic recurrence of either ovarian endometrioma or dysmenorrhea (11.1% vs. 31.1%, p = 0.013), compared with women under expectant observation by Kaplan-Meier survival analysis (χ2 = 5.448, p = 0.020) and Cox univariate assessment (hazard ratio of 0.336, 95% confidence interval 0.128–0.885, p = 0.027). Patients treated with LNG-IUS demonstrated a more prominent reduction in uterine volume (-14.1 ± 20.9 vs. 8.7 ± 48.8, p = 0.003) and higher percentage of complete pain remission (95.6% vs. 86.5%). For multivariate analysis, use of LNG-IUS (aHR 0.159, 95%CI 0.033–0.760, p = 0.021) and severity of dysmenorrhea (aHR 4.238, 95%CI 1.191–15.082, p = 0.026) were two independent factors associated with overall recurrence.

Postoperative insertion of LNG-IUS may prevent recurrence in symptomatic women with comorbidity of ovarian endometrioma and diffuse adenomyosis.