Levonorgestrel intrauterine device with absence of threads: don't take expulsion for granted! A case series of possible errors in ultrasound evaluation, in case of "lost IUDs".

Levonorgestel intrauterine devices are safe contraceptive methods, with even medical indications. However, they may present rare, but severe complications such as perforation and abdominal dislocation. Ultrasound assessment may be limited if a medicate intrauterine device is lost, due to its particular echogenicity.