The diaphragm is available by prescription only and must be fitted by a physician. Once the diaphragm is fitted, a woman can insert and remove it by herself. This dome-shaped rubber disk protects from pregnancy in two ways. The diaphragm blocks sperm from entering the cervix. Spermicide jelly placed inside the rubber dome before insertion will kill any sperm it comes in contact with. Once inserted, the diaphragm is effective for up to six hours.