Medicated intrauterine systems for treatment of endometriosis-associated pain

Medicated intrauterine systems (IUSs) are intrauterine devices that act by means of the local release of a medication. The levonorgestrel (LNG)-IUS is a T-shaped device that releases the progestogen LNG directly into the uterine cavity. The LNG-IUS can be used with noncontraceptive, therapeutic intent for idiopathic menorrhagia, hormonal replacement therapy in conjunction with oral or transdermal estrogens, and endometriosis or adenomyosis-associated pain. For this last indication, however, the use of the LNG-IUS is still under clinical investigation.