Report of ectopic pregnancies associated with the levonorgestrel intrauterine system

We describe the first case of tribal pregnancy following an LNG-IUS (20 mcg/day) failure in the UK since the product was marketed (case one); and an ovarian ectopic pregnancy with an LNG-IUS in situ but most probably unrelated to it (case two). In the discussion we consider: the performance of the LNG-IUS within scientific trials with regard to rates and ratios of ectopic pregnancy; the mechanisms of contraceptive action of this system; and the value of this knowledge in assessing use of the IUS in women with known risk factors for ectopic pregnancy.