27th June 2023

Intrauterine Contraception

here are two types of these long-acting contraceptives currently available in the UK: the copper intrauterine device (IUD) and the levonorgestrel intrauterine system (IUS). Both are inserted via the cervix and sit in the uterus with threads into the vagina (which allow the presence of the contraception to be checked after each menstrual cycle).

The copper IUD prevents fertilisation due to copper’s toxicity to ova and sperm. The IUS uses progestogenic effects within the endometrium to prevent implantation of the fertilised ova and thickens cervical mucus preventing sperm from entering the uterus; both methods are 99.2% effective. The IUS needs to be replaced every 3-5 years and can be used as a treatment for menorrhagia; disadvantages include the risk of expulsion and perforation of the uterus wall on insertion. The copper IUD is replaced every 5-10 years and is hormone-free, so it is safe for women with a history of blood clots and breast cancer. It can be associated with heavier menstrual bleeding, but this is not a contraindication.