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 µg/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.