The Intrauterine System (IUS)

The Intrauterine system is a t shaped device around the size of a matchstick similar in shape to the intrauterine device or IUD. More commonly known as a Mirena, it contains a hormone known as levonorgestral a common component of several types of contraceptive pill. The Mirena is placed inside of the uterus and works by slowly releasing progestogen into the body at a constant rate. The hormone assists in contraception by thickening the mucus within the cervix which helps to block entry of the sperm into the womb. As with other progestogen based contraceptives, the lining of the uterus is also thinned. This lowers the chances of a fertilized egg becoming accepted. In some instances, the progestogen inside the Mirena has also been known to prevent the release of eggs from the ovaries. Structurally, as with the IUS, the device has two threads which hang slightly down from the vagina and are most commonly used by doctors to check and remove the device correctly.