MODEL RELEASED. Intra-uterine device (IUD), conceptual composite image. An IUD is a Y- or T- shaped contraceptive device that fits into the uterus and prevents implantation of a fertilised egg, thus blocking pregnancies. At centre, a gynaecologist holds an IUD and its insertion tube. A training model of an IUD in place is at upper centre. At left is the chair in which women receiving an IUD sit. At right is an ultrasound scanner, which can be used to check the IUD is in the correct position.