Device Description and Placement
The levonorgestrel intrauterine device (IUD), marketed as Mirena, is a medicated device that is inserted into the uterine cavity where it delivers a small daily dose of levonorgestrel (20 mcg per 24 hours) directly into the uterus. 3, 4
- The device consists of a T-shaped frame with a silastic reservoir attached to the vertical arm that releases levonorgestrel into the uterine cavity. 3
- Mirena is placed at the fundus (top) of the uterus during an insertion procedure performed through the cervix. 2
Insertion Procedure Overview
The insertion involves several key steps that confirm intrauterine placement:
- A uterine sound is inserted through the cervix to measure the depth and direction of the uterine cavity before IUD placement. 2
- The Mirena device is then inserted through the cervix using an insertion tube until it reaches the uterine fundus. 2
- The IUD arms are released inside the uterus, and the inserter is removed while the strings remain extending through the cervix into the vagina. 2
Mechanism Requiring Intrauterine Placement
The primary mechanism of action depends on intrauterine placement—the device prevents fertilization by inhibiting sperm motility and thickening cervical mucus, with pronounced endometrial suppression occurring from the direct delivery of levonorgestrel into the uterine cavity. 1, 3
Common Confusion
You may be confusing Mirena with contraceptive implants (such as Nexplanon), which are placed subdermally (under the skin) in the upper arm. 5 These are completely different contraceptive methods with different insertion sites and mechanisms.