- Perforation of the uterus by an intrauterine contraceptive device (IUD) is a rare, and serious complication, occurring in 1/350 to 1/2500 insertions. Perforation by IUDs can involve several neighboring organs such as the bladder and rectosigmoid. We report two cases of IUD perforations involving the appendix, both inserted during lactation. The first case is an asymptomatic patient in early pregnancy and the second is a woman whose original presentation was chronic lower abdominal pain. The presence of copper in the abdominal cavity can lead to adhesion formation and subsequent abdominal pain, bowel obstruction or infertility. Thus, we believe that when an IUD is located in the abdominal cavity it should be removed even in an asymptomatic patient. In addition, these cases might suggest postponing the use of this contraceptive method in lactating women.