Safety and comfort of long-term continuous combined transdermal estrogen and intrauterine levonorgestrel administration for postmenopausal hormone substitution - a review.

Objective: To review the endometrial safety and patient acceptability of long-term use of continuous transdermal estrogen substitution combined with intrauterine release of levonorgestrel (LNG) in postmenopausal women. Design: One-hundred and fifty-three women who utilized the regimen for 2 IUD cycles were followed-up for a period of 10 years. Histology of the endometrium was evaluated at the end of this period to assess endometrial safety and the acceptability of the method was assessed based on the replacement rate of the LNG-IUS and continuation of ET. Results: The regimen, administered over a 10-year period, was very well tolerated and the IUD was retained well and no expulsions occurred. The dominant endometrial histologic picture was that of inactive endometrium characterized by glandular atrophy and stroma decidualization (Kurman classification 5b). No cases of endometrial hyperplasia were found. Conclusion: The low systemic absorption of LNG could be desirable, thus allowing for maximization of the beneficial effects of ET on organ tissues (e.g. cardiovascular tissues and breast). Repeat LNG-IUS is associated with high patient satisfaction. If started before the age of 60, this regimen could be advised for lifelong prevention of cardiovascular disease and other prevention measures. The LNG-IUS was shown to effectively oppose the secondary effects of systemic estrogen on the endometrium tissue resulting in strong suppression during the entire period of EPT.