The levonorgestrel intrauterine system: more than a contraceptive

Abstract

Levonorgestrel can be released directly into the uterine cavity, where it causes pronounced endometrial suppression, although the dose of hormone is so low that the effect on ovarian function is negligible. The levonorgestrel-releasing intrauterine system (LNG-IUS) consists of a plain Nova-T device with a silastic reservoir attached to the vertical arm. The silastic reservoir is impregnated with levonorgestrel and is covered with a rate-limiting silastic membrane. The release rate oflevonorgestrel is approximately 20 microg/24 h for at least 5 years. The contraceptive efficacy of the LNG-IUS has been studied in a randomized, comparative trial over 5 years. A total of 1,821 women were fitted with the LNG-IUS and were compared with 937 women who were using the copper-releasing device, Nova-T. The continuation rates were 46.9 for the LNG-IUS and 44.5 for the Nova-T. The cumulative gross pregnancy rates were 0.5 for the LNG-IUS and 5.9 for the Nova-T. The Pearl index after 5 years was 0.09/100 woman-years for the LNG-IUS and the ectopic pregnancy rate was 0.02/100 woman-years. There were less withdrawals because of bleeding problems and pelvic inflammatory disease in the LNG-IUS group compared with the Nova-T group, but there were more withdrawals because of hormonal side-effects and absence of bleeding. There were no differences in the return of fertility after removal of the LNG-IUS and the Nova-T. All women will notice a change in their bleeding pattern after the LNG-IUS has been inserted and some will initially experience many days of spotting. It is extremely important to counsel women about the changes in bleeding pattern that will occur with the LNG-IUS before the system is fitted. One of the advantages of the LNG-IUS is that menstrual blood loss will decrease (and therefore hemoglobin levels will increase), which means that the LNG-IUS is one of the most effective reversible long-term treatments of idiopathic menorrhagia. The LNG-IUS can be used successfully throughout the reproductive period for effective contraception and treatment of menorrhagia. In addition, this system provides endometrial protection. Women who suffer from climacteric symptoms while they are using the LNG-IUS can be given estrogen to relieve their symptoms.