Contraception Through Caps

Caps are female barrier methods designed to prevent sperm from entering the cervix. There are several different kinds of cap, but all work on the same basic principle: a dome of thin rubber or plastic holds spermicide against the cervix, so that any sperm reaching that region are killed or blocked. It is important to remember that caps are not intended to work by physically blocking off the cervix — the contours of the vagina make this very difficult to do effectively. They work mainly by holding spermicide against the cervix, where it is most needed — this is why they should always be used with spermicide for maximum effectiveness.

Early prototypes of caps were known in many parts of the world. China and Japan used discs of oiled silk paper; women in Europe and the Far East used moulded wax wafers, hollowed-out half-fruits such as lemons, and even small cups. The use of leaves, sponges, wool soaked in oil, and other similar techniques has also been recorded.

The modern diaphragm was invented in 1838, following the discovery of vulcanized rubber, but only became well-known in the 1880s. The name ‘Dutch cap’ which is sometimes given to the diaphragm comes from the ardent promotion of its use by a Dutch doctor. The diaphragm was very popular with early family planners, because for the first time it gave women control over their own fertility; they did not have to rely on the man abstaining from sex or using contraception himself.

Many women in the 1940s and 50s used caps successfully for the whole of their fertile years. In the 60s and 70s, the era of the pill and the IUD, caps lost popularity because of their relative inconvenience and inefficiency compared with the new methods; caps suddenly seemed old-fashioned. Now, with the swing against the pill and IUD, they are experiencing a relative comeback, although they are still used by only about six per cent of British women who use contraception.

There are four main types of cap. By far the best known and the most widely-used is the diaphragm; most of this section will be concerned with using this type of cap. Other types are the cervical cap, the vault cap and the vimule — these will be covered at the end of the section, as much of their usage is similar to that of the diaphragm.


The diaphragm or Dutch cap (also often called just ‘the cap’) fits between the pubic bone and the back of the vagina. It is held in place by the vagina’s muscles and also by the spring around its rim. There are three types of diaphragm, named according to the type of spring used around the rim. The first kind is the arcing spring; then there is the coil spring, which is particularly suitable for women who have not had any children. The third kind is the flat spring; it can be used by women with poor muscle tone. The diaphragm is a dome of thin, soft rubber. It can be obtained in sizes 50-100mm, which is the measurement of the external diameter of the dome. Although the fitting is fairly straightforward, it needs to be done by a doctor or other trained family planning practitioner, to ensure a correct fit. As the vagina expands during the arousal that accompanies lovemaking, the largest comfortable size is chosen. If the diaphragm is too small it may become dislodged during lovemaking; if it is too big, it will be uncomfortable to use.

Most doctors will fit a diaphragm; caps and spermicides can be obtained on prescription or free from family planning clinics. The woman is taught the correct method of inserting and removing a diaphragm of the appropriate size at the first visit, and then is usually asked to return a week later with the cap already in place, so that the instructor can ensure that the diaphragm is correctly positioned. A diaphragm should be checked for fit every six months , as alterations can occur in the body or in the diaphragm itself. The fit should also be checked after any pregnancy (whether it ends in miscarriage, abortion or birth), and after a weight change of more than 7-10 lbs (3-4 1/2kg). If the diaphragm is fitted while you are breastfeeding, the fit should be checked six weeks after weaning or after normal periods begin. If you are a virgin when you are being fitted for a diaphragm, you should return for a fitting check six weeks after you start your sex life. The diaphragm should be checked regularly for flaws or tears.

The diaphragm can be inserted up to two hours before sex. Squeeze spermicide cream or jelly onto both sides of the dome; the exact amount will depend on the brand of spermicide you are using — each type will carry its own instructions. Spread the spermicide around with your finger to coat both sides of the dome, and smear a little around the rim — only a little, as otherwise the diaphragm may slip out of place.

The insertion itself can seem impossibly tricky when you try it the first time. However, it is only a knack which, once you are confident, will take only a matter of seconds. A diaphragm inserter has been developed, but it is probably no easier to use than the conventional method of insertion; also it may cause injury to the tender membranes of the vagina if it is not used very carefully. Squeeze the diaphragm at both sides so that it becomes long and narrow (if you have put too much spermicide on the rim, you may find that it shoots out of your hand at this stage!). Insertion is easiest if you stand with one foot on the bed, chair or toilet seat, although once you are confident, insertion can easily be done squatting or lying down.

With one hand, spread the labia apart; with the other, push the diaphragm gently along the vagina and over the cervix, then release. The rim of the diaphragm springs back into its normal position, and the diaphragm should be lodged in place over the cervix and behind the pubic bone. Check with your fingertip; if the diaphragm is correctly positioned you will be able to feel the cervix through the dome. When the diaphragm is fitted, neither partner should be able to feel it during sex, although occasionally the man’s penis may hit the rim. Different positions for lovemaking may make this more or less noticeable.

Some instructors recommend that you insert more spermicide into the vagina as a matter of course once the diaphragm is in place. Others say that you only need to do this if more than two hours elapse before sex, or if you make love a second time. The diaphragm must be left in place for at least six hours after sex; never remove the diaphragm to add more spermicide if you make love a second time — simply place the spermicide in the vagina.

The easiest method of removing the diaphragm is simply to hook one fingertip over the rim and ease the diaphragm out. Again, this is most easily done with one foot on a bed or chair, or when squatting. After use, wash the diaphragm in water; you can use unperfumed soap, but water alone is often enough as the spermicides are water-soluble. Rinse the diaphragm well and pat it dry thoroughly, then store in its container in a cool place. High temperatures and humidity can damage the rubber.


A cervical cap fits snugly over the cervix like a thimble; although it fits more closely than the diaphragm, it is still generally used with a spermicide. Cervical caps have never been very popular in this country, although Marie Stopes preferred them to diaphragms in her clinics; they are generally used by women who want to use a cap but have difficulty in retaining a diaphragm. Because the close fit over the cervix is vital, cervical caps can only be used by women who have a cervix which is regular in shape, healthy, and easily accessible. The cap is generally made of rubber, with a raised hollow rim. Sizes are measured by the internal diameter of the rim, and range from 22-31mm; the size chosen matches the base of the vaginal part of the cervix.

The cap is smeared on both surfaces with spermicide, and then compressed between thumb and forefinger. It is guided into the vagina and onto the cervix, which can be felt through it. Alternatively, spermicide can be placed inside the dome only, and then a vaginal spermicide added after insertion. Generally the same rules apply as for the diaphragm; the cap can be inserted up to two hours before sex, and should be left in position for six hours subsequently. Some practitioners have claimed that a cervical cap can be left in place throughout the month and only removed for menstruation, but most experts are unhappy with this idea and recommend that it should be removed after each use (although for further developments along these lines, see p.140). The cap is removed by inserting a fingertip under the rim and easing it off the cervix; one type has a hole in the rim for an optional removal thread.


The vault cap is bowl-shaped with a thin centre and a thicker outside. It has no rim, but is held in place by suction. Sizes vary from 50-75mm (the outside diameter of the rim); the correct size is the smallest one that fits evenly.

The vault cap is not as easy to use as the diaphragm, but can be useful for women whose vaginal muscles are weak or whose cervix is damaged. Spermicide is put on the inside and outside of the cap, but not on the rim as this would spoil the suction. The cap is inserted, and when it is in the correct position the centre is depressed with a fingertip; this expels air and produces the suction to hold it in place. Like the other caps, the vault cap should be inserted not more than two hours before sex and left in position for six hours subsequently. One difference is that the downward straining of a bowel movement while you are wearing the vault cap may break the suction and dislodge the cap, so it is always worth checking that it is still in place afterwards.


The vimule cap is shaped like a deep-brimmed hat, and is a cross between the cervical and vault caps. Once again the cap is held in place by suction, and can be useful for women who cannot hold other types of cap in place, for instance those with poor or damaged vaginal walls. Instructions for using spermicide, insertion and removal are similar to the other small caps; as with the cervical cap, a thread can be attached to help removal.


Like other barrier methods, caps are good choices for couples who don’t want to use an IUD or hormonal methods, and who don’t want to practise periodic abstinence from sex. One enormous advantage of caps over sheaths and spermicide alone is that caps don’t have to be inserted at the time of intercourse, so there is no interruption of lovemaking. (Of course they can be inserted during lovemaking if you prefer, or if you are not already prepared.) The caps themselves and stocks of spermicide are available on prescription or free from family planning clinics. The choice of different types of cap means that many women could use a cap successfully if they wanted to.

There is some evidence that using a cap reduces the transmission of some kinds of VD and also that, like the sheath, a cap reduces the risk of cervical cancer by keeping the semen away from the cervix. As with other barrier methods, there is no problem re-establishing fertility when a pregnancy is desired, and no known risk of harm to either partner. There is also no reason to suspect that using a cap can cause any damage to a baby conceived after (or while) using this method of contraception. The need to use spermicide is often helpful to women with little natural lubri cation, although some men and women find that the amount necessary actually decreases their sensations. Caps can be very useful if you are making love during a period, as they hold back much of the menstrual flow In addition, caps, when used conscientiously, are a fairly successful means of contraception.


Like other barrier methods, using a cap requires that you must prepare for sex each time, and carry the cap and spermicide with you when you go away. Any people who find a ‘mechanical’ method of contraception unpleasant are likely to dislike the preparation, insertion, removal and washing routine of caps. It can be difficult to keep the method private, because of supplies of spermicide around the house, washing the cap after sex etc.; some parents may find this embarrassing.

A cap needs to be fitted by a trained person, and cannot be bought over the counter. Some women cannot wear a diaphragm, particularly those with an unusually-positioned uterus, a prolapse (where the uterus has slipped down the vagina because of poor muscle tone), a rectocele or cystocele (a bulge in the vaginal wall from the urethra or intestine). It is also true that using a diaphragm can aggravate problems of the urinary tract, such as cystitis; all women are encouraged to empty their bladder regularly while wearing a diaphragm. Happily, many of these problems can be overcome by using one of the other types of cap. Some sexually inexperienced women may find the psychological or physical relaxation needed for insertion difficult to achieve; some few women may be allergic to one component of the rubber used in the cap.


The diaphragm is the cap most commonly assessed regarding success and failure rates, as it is the most commonly used. Reliable studies have shown failure rates as low as 2 per 100 woman/years, which is the theoretical failure rate of the diaphragm with spermicide. The actual failure rate has been as high as 29 in one study, with an average of 1015. This is really a very large difference. Most pregnancies arise because the woman was not instructed properly on how to fit the diaphragm correctly, or because the diaphragm became damaged, dislodged or mis-shapen, because the cap was removed too early, or, more commonly, because it was only used intermittently and couples decided to take a risk.

Failure rates are highest among new users, especially those changing from a more ‘automatic’ method such as the pill or IUD. The longer a women has been using a cap, the fewer the unwanted pregnancies — this is probably a combination of factors. The older woman is probably more experienced in the technique of insertion, she is more mature and takes fewer risks, and her fertility is lower than that of a younger woman. Regarding the other caps available, the cervical and vault caps show similar success rates to the diaphragm when they are used with spermicide. So far, there do not seem to be adequate data for the vimule. As with many other methods, the successful use of a cap depends very much on the motivation and conscientiousness of the user, and the skill of the instructor.


Caps, when used conscientiously, are fairly successful methods of contraception. The best candidates as cap users are women who don’t want to use the pill or IUD or rhythm methods, who are at ease with their own bodies and don’t mind the mechanics of insertion and removal, and who are happy, with their husbands, to include regular use of the cap in their sex life. Women who have cultural, social or personal taboos about handling their own body, or who dislike having to take active responsibility for contraception, are likely to find using a cap distasteful and will probably not be enthusiastic users even if they have a cap fitted.

Caps are good contraceptives for women approaching the menopause, as fertility is reduced then while the risks of the pill are increased. If it is important that you don’t get pregnant, then you will need to use the cap with great dedication — and even then you might not be successful. Like the sheath, the cap is an excellent back-up method for pill emergencies, between other methods, before operations (when you have to come off the pill), and when waiting for a clear sperm count after a vasectomy. It is also a very useful method for nursing mothers, and is a good tide-over for the ‘unsafe’ days of rhythm methods.