The effect of the levonorgestrel-releasing intrauterine system, Mirena® on mast cell numbers in women with endometriosis undergoing symptomatic treatment

Mirena® causes a reduction in mast cell numbers in ectopic and eutopic endometrium in women undergoing symptomatic treatment of minimal to moderate endometriosis. This reduction could partly explain the efficacy of Mirena® in modulating pain in these women.