We undertook the ECLIPSE trial, a pragmatic, multicentre, randomised controlled trial designed to assess the clinical effectiveness of LNG-IUS for HMB compared with usual medical treatment in primary care. Initially, we considered outcomes for women after 2 years of follow-up.Women aged between 25 and 50 presenting to their GPs with HMB, occurring over at least three consecutive cycles, were considered eligible. Consenting women were randomised to having a LNG-IUS fitted, or usual medical treatment, chosen as clinically appropriate to needs by the woman and her doctor.The usual medical treatment options were mefenamic acid, tranexamic acid, norethisterone, the combined oral contraceptive pill (any formulation), desogestrel or methoxyprogesterone acetate injection. Subsequently, treatments could be changed between the usual medical treatment options, from the LNG-IUS to other medical treatments, or vice versa, or could be ceased completely in line with usual clinical practice (e.g. due to perceived lack of benefit, side effects, change in need for contraception, referral for endometrial ablation or hysterectomy).The primary outcome measure was the condition-specific questionnaire designed to capture the impact of HMB on women’s day-to-day life. Summary scores range from 0 (not affected) to 100 (worst affected).