Background: The main reason for discontinuation of the levonorgestrel-releasing intrauterine system (LNG-IUS) is unpredictable bleeding pattern.
Methods: The objective of the study was to evaluate the endometrial histology, microvascular density and calibre, and the quantification of matrix metalloproteinase (MMP-3) in long-term users of LNG-IUS, with and without bleeding. Endometrial biopsies were obtained from 58 healthy women, 29 who maintained some degree of endometrial bleeding and 29 who were amenorrhoeic.
Results: In the histological analysis, the majority of samples displayed a progestin-modified appearance. The major glandular diameter and the perimeter were significantly greater in the group of women with amenorrhoea. A significantly higher number of leukocytes was found in the group with bleeding (P = 0.014). No significant correlation was observed between the microvascular density or calibre and the bleeding pattern. MMP-3 showed a significantly higher number of reactive cells (P = 0.005) in the group who maintained some degree of bleeding.
Conclusions: Women using LNG-IUS who maintained endometrial bleeding during its use presented a higher number of leukocytes and MMP-3 in the endometrium when compared to women using LNG-IUS who became amenorrhoeic. However, the results did not provide evidence for microvascular pattern changes.
Copyright 2004 European Society of Human Reproduction and Embryology