Diaphragm and Cervical Cap
Effectiveness in Preventing Pregnancy
- Of 100 women who use a diaphragm with spermicide each year, about 12 may become pregnant.
- Of 100 women who use the cervical cap each year, about 17 to 23 of them may become pregnant.
- The risk of pregnancy is much greater in women who do not use the diaphragm or cervical cap consistently and correctly.
What are diaphragms and cervical caps?
The diaphragm and cervical cap are silicone cups that are used with a special gel or cream called spermicide (a substance that kills sperm). The diaphragm or cervical cap is inserted into the vagina and over the cervix to keep sperm from entering the uterus, meeting with and fertilizing an egg.
How do I use a diaphragm or cervical cap?
The diaphragm and cervical cap come in different types and sizes. You should be fitted by a trained healthcare provider who will ensure that you can insert the device properly. The diaphragm or cervical cap should be checked for holes or weak spots. A diaphragm or cervical cap with a hole should not be used. After a pregnancy it may be necessary to have the fit of the diaphragm or cervical cap checked by a healthcare provider. Oil-based lubricants, such as hand lotion or petroleum jelly, or vaginal medications (for example, for yeast infections) should never be used because they can damage the diaphragm or cervical cap.
- Empty your bladder (pee) and wash your hands.
- Squeeze a tablespoon of spermicidal gel into the diaphragm cup or cervical cap.
- Insert the diaphragm or cervical cap into the vagina as instructed when it was fitted. It must cover the cervix. Insert a finger into the vagina to check that the diaphragm or cervical cap is in place.
The diaphragm can be inserted up to two hours before sexual intercourse.
The cervical cap can be inserted up to 42 hours before sexual intercourse.
The diaphragm or cervical cap should be left in place for at least six hours after sex. Avoid douching with either device in place.
The diaphragm should not be in the vagina for more than a total of 24 hours. If you have sex more than once, add additional spermicidal gel into the vagina before intercourse without moving the diaphragm.
The cervical cap should not be in the vagina for more than a total of 48 hours. You do not need to apply additional spermicide if you have sex more than once during the time the cap is in place.
The diaphragm or cervical cap is removed by slipping a finger into the vagina and under the rim to gently slide it out.
After removing the diaphragm or cervical cap, clean it with mild soap and water, allow it to air-dry naturally, and store it somewhere cool and dry. Do not use disinfectants. After a sexually transmitted disease (STD) or vaginal infection, the diaphragm or cervical cap should be discarded and replaced with a new one.
How effective is each method?
The effectiveness of using a diaphragm or cervical cap depends on how well you follow the instructions for use.
- Diaphragm: With typical use, 12 out of 100 women may become pregnant in the first year of use.
- Cervical cap: With typical use, about 17 to 23 out of 100 women may become pregnant in the first year of use.
If you use the diaphragm or cervical cap according to instructions, each time you have sex, chances of pregnancy decrease.
The exact risk of pregnancy when using a cervical cap depends on whether you use the cap correctly each time you have sex and whether or not you have had a vaginal birth. The vagina and cervix are stretched by giving birth vaginally, which means the cervical cap may not fit as tightly as it should. The fit should be rechecked by a healthcare provider after giving birth.
How do I get each method?
All diaphragms and cervical caps require a prescription, but spermicide is available over the counter at pharmacies and some grocery stores.
There are two types of diaphragms available in the United States:
- Individually sized diaphragm, which must be fitted by a healthcare provider to get the best fit for you.
- One-size diaphragm, which fits most, but not all women.
All cervical caps must be fitted by a healthcare provider.
Once you have a prescription, you can buy a cervical cap and spermicide at a pharmacy.
If your provider does not carry the one-size diaphragm, you can order it online or a pharmacy can order it for you. The individually sized diaphragm, if not available from your healthcare provider, may be ordered for you by your healthcare provider from the manufacturer.
If you use a diaphragm or cervical cap, you will need to be refitted by your healthcare provider if you experience certain events such as a pregnancy leading to vaginal birth, a miscarriage, or abortion after 14 weeks of pregnancy, or significant (20 percent or more) weight gain or loss. Talk to your healthcare provider about when refitting may be needed.
Advantages of the diaphragm and cervical cap
- Diaphragms and cervical caps have very few side effects or major health risks.
- Each method is safe and can be inserted by a woman herself prior to use.
- The one-size diaphragm does not require fitting.
- You and your partner usually cannot feel the diaphragm while having intercourse.
- The diaphragm is safe and effective when used correctly and consistently.
- The diaphragm can be inserted up to six hours before having sex and can remain in place for up to 24 hours. The cap can be put it in place before having sex and left in for up to 48 hours (two days).
- The cap is more effective in preventing pregnancy in women who have never given birth vaginally and who use it correctly and consistently for each sexual encounter.
- These methods are private. It is your choice if your partner knows about them.
Drawbacks of the diaphragm and cervical cap
- The diaphragm and cervical cap do not protect against STDs, including HIV. Always use a condom to reduce the risk of STDs.
- Each method requires a visit to a healthcare provider and prescription.
- Each method must be inserted before every act of intercourse.
- These methods may be hard to put in place.
- These methods should not be used during menstruation.
- Some women using the cervical cap experience pain or discomfort during intercourse.
- The cervical cap has a higher failure rate than other methods, and the failure rate is highest among women who have given birth vaginally.
- Some women may experience irritation, allergic reaction to the spermicide, or urinary tract infection (UTI, cystitis).
- Spermicides containing nonoxynol-9 (N-9) can irritate the vagina and rectum. This may increase the risk of getting HIV from an infected partner.
- If the diaphragm is left in place longer than 24 hours or the cervical cap is left in place longer than 48 hours, there is a risk of toxic shock syndrome (TSS), a rare but potentially life-threatening condition.
- The diaphragm must be re-checked for fit by your healthcare provider following childbirth or significant weight gain or loss.
- Contact with silicone-based lubricants can deteriorate a silicone diaphragm or cervical cap. Do not use lubricants or any other vaginal products containing silicone oil when you are using a diaphragm. Ask at your local pharmacy about which brands of lubricants contain silicone oil, so you know which ones to avoid using with your diaphragm or cervical cap.
Content last reviewed on August 25, 2017