Introduction: This study compares the efficacy of a levonorgestrel-releasing intrauterine system (LNG-IUS) and a low-dose combined oral contraceptive (COC) in reducing adenomyosis-related pain and bleeding.
Materials and methods: A randomized clinical trial included 62 participants complaining of pain and bleeding that was associated with adenomyosis. Participants were randomly assigned to either LNG-IUS or COC treatment. The outcomes included the improvement of pain using a visual analogue scale, menstrual blood loss using a menstrual diary and estimated uterine volume by ultrasound for 6 months of treatment. We also compared uterine arteries and intramyometrial Doppler indices before and 6 months after treatment with both LNG-IUS and COCs.
Results: Both treatments significantly reduced pain after 6 months of use; however, the reduction was greater in the LNG-IUS group (from 6.23±0.67 to 1.68±1.25) compared with the COCs group (from 6.55±0.68 to 3.90±0.54). Both treatment arms significantly decreased the number of bleeding days, uterine volume and Doppler blood flow in the uterus from before to after treatment. These effects were more significant in the LNG-IUS arm compared with the COC arm.
Conclusion: Both LNG-IUS and COCs decreased the pain and menstrual bleeding that is associated with adenomyosis. However, LNG-IUS is more effective than the COCs in reducing pain and menstrual blood loss. This effect may be secondary to the decrease in uterine volume and the increase in blood flow resistance.
Keywords: Adenomyosis; COCs; Dysmenorrhea; LNG-IUS; Mirena.
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