Approximate effectiveness: 90%
No protection against STDs
The Cervical Cap is like a smaller version of the Diaphragm. It looks like a rubber or plastic thimble. To use it, it must be placed into the vagina and it must cover the cervix. It must be placed against the cervix at least a half hour before having sex and must be left in place at least eight hours. It may be left in place for as long as two days. Your doctor or gynecologist must be consulted about fitting and how long it should be left in.
The cervical cap offers a barrier to any sperm trying to reach the cervix. If sperm can't get through the cervix to the uterus then they can't fertilise an egg. It can be used many times and can be used with, or without spermicide which may or may not increase the effectiveness of preventing pregnancy.(Not everyone agrees on whether the spermicide makes a difference in failure rates. The cap may be slightly uncomfortable but if it is properly fitted by your doctor, there should be minimal or no discomfort. To be effective it must fit properly and must be inserted properly and that may take some practice. Even a properly fitted cervical cap, because it is essentially held in place by suction at the cervix, could be knocked out of place during sexual intercourse. As well, you should get a checkup every three months.
You'd be well advised to discuss the Cap with your doctor.