The levonorgestrel-releasing intrauterine device
Toivonen, J.
Advances in Contraceptive Delivery Systems Cds 10(3-4): 191-198
1994
ISSN/ISBN: 1012-8689 PMID: 12287838 Document Number: 285199
The levonorgestrel-releasing (LNG) IUD is a simple Nova T device with a Silastic reservoir of levonorgestrel in the vertical arm. It releases 20 mcg/day over 5 years. LNG IUD is very effective (about 99%) at preventing unplanned pregnancies. Circulating levels of levonorgestrel peak within 24 hours after LNG IUD insertion and are much lower than the levels in the endometrium. The high endometrial concentrations of levonorgestrel bring about a considerable reduction in the amount of bleeding, particularly oligomenorrhea. Other beneficial effects include prevention of iron deficiency anemia and protection against pelvic inflammatory disease (PID). Special counseling about changes in menstruation patterns for both providers and users is needed to prevent unwarranted discontinuation of LNG IUD. Hormonal side effects should also be discussed. Discontinuation for amenorrhea is more likely in LNG IUD users than copper IUD users (4.5% vs. 0; p = .001). LNG IUD hormonal side effects are more likely to result in discontinuation than those of the copper-releasing IUD (9% vs. 1.7%; p = .001). On the other hand, LNG IUD users are less likely to stop use for pregnancy, bleeding, and PID than copper IUD users (0.3% vs. 4.1%, p = .001; 11.3% vs. 17.9%, p = .002; and 0.5% vs. 1.5%, p = .022, respectively). Levonorgestrel generally has an effect on the ovaries just during the 1st year of use. It causes scanty and thick cervical mucus, its major contraceptive mode of action. LNG IUD can treat idiopathic excessive menstrual bleeding.