Objective To review the literature on usage of the levonorgestrel intrauterine system (LNG IUS) in women with fibroids or adenomyosis in an attempt to develop a pragmatic approach when faced with enlarged uteri.

Data sources Computerised searches of MEDLINE and EMBASE up to December 2000. Some of the information was obtained from references listed in the primary sources and references already known to the authors.

Study selection Studies and case reports were excluded if they did not specifically provide information about LNG IUS usage in women with fibroids and adenomyosis.

Data extraction and synthesis After perusal, each relevant publication was summarised and appraised in terms of whether it contained information relevant to the stated objective.

Discussion This area is sparsely researched, as there were no randomised-controlled studies. One large contraceptive study suggests the LNG IUS has a protective effect from the complications of uterine fibroids and smaller case studies suggest it is also useful in women with symptomatic fibroids. However, there is also evidence of an increased risk of expulsion and there may be a place for initial adjunctive medical treatment to minimise this risk. An observational study and isolated reports of women with adenomyosis report significant symptomatic relief in these women.

Conclusion Available data refute the notion that uterine enlargement is a contraindication to insertion of the LNG IUS, but there appear to be reasons for a cautious approach when dealing with pathological uteri.