A diaphragm or cap is a barrier method of contraception that fits inside the vagina and covers the cervix (neck of the womb). It must be used with a spermicide (a chemical that destroys sperm) to be effective. It must stay in place for at least six hours after sex.
A nurse or doctor will need to examine you to help you to decide which type of diaphragm or cap is best for you, then choose the most appropriate size, teach how to use the device and perform the initial fitting. If used according to the instructions, diaphragms and caps are 92-96% effective.