A cervical cap is a rubber device something like a diaphragm, but only about an inch in diameter, held in place by suction rather than by the surrounding anatomical structures. While a cervical cap covers the cervix and closes off the entrance to the uterus, it does not block off the entire width of the vagina. For this reason, and also because it is used with less spermicide, a cervical cap is less reliable than a diaphragm, though it is more convenient. Caps are prescribed less frequently than diaphragms, but some women’s clinics and university health services do offer them. The woman who might choose a diaphragm might also find a cervical cap suitable.
How do you use a cervical cap?
Cervical caps come in different sizes, so you must be fitted by your caregiver, who will give you a prescription. Some women, especially those who have had several children, are difficult to fit because of the size or shape of the cervix.
You may insert the cap as much as twenty-four hours before intercourse. Fill it about one-third full with a spermicide and insert it into your vagina — directly against the cervix, where it should attach by suction. You need not apply extra spermicide outside the cap, and you can use it for more than one act of intercourse.
After intercourse you should leave the cap in place for six to eight hours to let the spermicide do its work. Some manufacturers say that you can leave it in place as long as a week, but the cap can develop an odor if left that long. It is probably better to remove it at least every other day. You should not use a cervical cap for contraception during your menstrual period, as the flow may break the seal and displace the cap.
How reliable is a cervical cap?
Some studies have suggested that a cervical cap has a method failure rate of 6 percent and an actual failure rate of about 18 percent, but my experience with patients suggests that these estimates are optimistic. I estimate the highest possible effectiveness to be somewhere in the range of 92 percent, maybe a little less.
What are its advantages and disadvantages?
A cervical cap has the advantages of a diaphragm, plus it can stay in place much longer and is less messy. You can use it for more than one act of intercourse without additional spermicide. On the down side, it does not protect you against disease and is less reliable than other barrier methods. A cervical cap has no known side effects, though occasional women complain of urinary tract infections; these are less likely than with a diaphragm, because the cervical cap does not rest against the urethra.
As with a diaphragm, the initial cost is fairly high. The cap itself costs something more than thirty dollars, but you also pay for the office visit to your caregiver. Since a cervical cap takes more time to fit, your doctor might suggest a special appointment for the fitting rather than doing it during your regular checkup. Spermicides cost about seven to ten dollars per tube.
Contraceptive sponges are small, circular sponges impregnated with spermicide that fit into the vagina and cover the cervix. They were withdrawn from the market in this country in 1995, but are available in Canada and may in the future return to the U.S. market.