Efficacy of the levonorgestrel-releasing intrauterine device is associated with different subtypes of adenomyosis: a retrospective study

Background Although the levonorgestrel-releasing intrauterine device (LNG-IUD) has been widely applied in the treatment of adenomyosis, not all the patients are satisfied with its efficacy. The present retrospective study aimed to investigate the efficacy of LNG-IUD on different subtypes of adenomyosis. Methods The study comprised a cohort of 207 patients who received the LNG-IUD at the Women's Hospital, Zhejiang University School of Medicine, China, from June 2013 to June 2016. Different subtypes of adenomyosis were classified by magnetic resonance imaging (MRI) and patients were subcategorized into three groups (subtype I: intrinsic, n=70; subtype II: extrinsic, n=73; subtype IV: indeterminate, n=64). Multiple variables were compared among the different groups. Results Patient demographics, clinical features and the treatment effects of the LNG-IUD were compared between the three subtype groups. The numeric rating scale (NRS) and pictorial blood loss assessment chart (PBAC) score markedly decreased after insertion of the LNG-IUD compared with baseline in all patients in the three subtype groups (P<0.001 for all groups). Compared to the other two subtypes, the efficacy rate was lower and the spontaneous expulsion rate was higher in subtype IV adenomyosis patients than that in other two groups (P<0.05). The independent factor associated with the spontaneous expulsion of the system was suggested to be uterine size before IUD placement and bleeding amount after LNG-IUD treatment in the subtype I [P=0.029, hazards ratio (HR): 3.37, 95% confidence interval (CI): 1.09-6.88] and IV (P=0.045, HR: 1.02, 95% CI: 1.01-1.21) adenomyosis patients respectively. Conclusions The LNG-IUD is proved to be an effective approach to treat subtype I and II adenomyosis. However, further study is warranted to explore a more suitable protocol to treat this subtype IV adenomyosis due to the high incidence of treatment failure and expulsion.