Approximate effectiveness: 80-94%
Approximate cost: from $25.00 to $60.00 but it lasts for years. A spermicidal (sperm-killing) gel must also be used and the cost of that per tube, runs around $15.00 and needs to be replaced when the tube is empty)
Should not be considered as protection against STDs
The Diaphragm is a soft rubber rounded dome-shaped device which gets coated with a sperm killing (spermicide) gel. The female inserts it into her vagina up to two hours before having sex. It should be kept in place at least six hours after having sex. It is important that the spermicidal gel coats both sides of the diaphragm as well as the rim or edges of it.
You can get instructions on how to insert it from the doctor, the pharmacist, or the instruction sheet. When it is fully inserted, it should cover the cervix (at the top of the uterus, where it widens into the cervix) completely.
Since it must stay in (killing sperm and blocking their travel into the cervix) for at least six hours, if a woman wants to have sex again before that time, she has to remove the diaphragm, and reapply fresh spermicidal gel, and insert it again. When done with it, the diaphragm gets cleaned with cool water, dried and gets put away in its holder until the next time it is needed.
Diaphragms can last a long time but they should be inspected for holes or tears. If one is found, or if the woman's weight changes significantly, say 15 pounds either way, she should get re-fitted with a new one.