Intrauterine system (IUS)
The IUS is a small, T-shaped plastic device, which contains the hormone progestogen. The device is put into the womb through the vagina by a specially trained doctor or nurse.
The IUS is different to the copper bearing intrauterine device (Cu-IUD, or coil). The IUS contains hormones; the Cu-IUD does not.
It works by thickening the mucus around the cervix, which makes it harder for sperm to get through, and making the lining of the womb thinner so that a fertilised egg cannot implant.