The intrauterine system (IUS)
The intrauterine system (IUS) (known as multiple brand names, such as Mirena”) is a small T-shaped plastic device that is fitted in the uterus (womb). It provides contraceptive protection for up to five years.
The IUS steadily releases small amounts of a hormone called progestin which thickens the fluid around the neck of the uterus (stopping sperm from getting to an egg) and makes the lining of the uterus thinner so that a fertilised egg cannot grow. It also makes it harder for sperm to get into the uterus.