The vaginal diaphragm is a dome-shaped latex rubber or plastic membrane the rim of which is reinforced with a flexible metal spring. It is inserted high in the vagina in the posterior fornix so that the cervix (particularly the cervical os) is covered.

The cervical cap is thimble-shaped and made of plastic or hard rubber. It fits snugly over the cervix and is kept in place by a suction effect.

Diaphragms and cervical caps are available in different sizes. They have to be fitted individually by a doctor or family planning nurse. You should have the fit of the diaphragm or cap checked after a pregnancy or abortion, if you have lost or gained a lot of weight and after pelvic surgery.

Using these methods properly has to be learnt and requires practice. Your doctor or family planning nurse will give you the necessary instructions and advice.

How effective are the diaphragm and cervical cap?

The effectiveness depends to a large extent on proper fitting and committed use. The contraceptive action results solely from the mechanical covering of the cervix. In the acid milieu of the vagina sperm only remain capable of fertilizing for about 6 to 8 hours. The diaphragm and cervical cap must be left in place during this time. Both methods have a moderately high failure rate.

The effectiveness of both methods is increased by additional use of a spermicide. The spermicidal cream or jelly is placed in the bowl of the diaphragm or cap. It is important to remember that the spermicidal action takes a few minutes to develop and only lasts a limited length of time. If you have repeated or prolonged sexual intercourse you must place more spermicide in the vagina after a while. Be careful not to dislodge the cap or diaphragm in the process.

The diaphragm and cap must be left in place for at least 6 to 8 hours after intercourse. You should not bathe during this time either. The diaphragm must not be left in the vagina for more than 24 hours, the cap for not more than 48 hours.
With diaphragms or caps made of latex it is important to use only water-based, oil-free lubricants as oil-based preparations (e.g. massage oils, creams, petroleum jelly) attack the latex membrane and make it permeable. The same applies if you have to use vaginal creams or suppositories (e.g. for treatment of a fungal infection or for local hormonal replacement therapy).

To avoid damage the diaphragm and cap should always be handled very carefully and cleaned thoroughly after each use.

Advantages of the diaphragm and cervical cap

The diaphragm and the cervical cap are suitable alternatives for women who cannot or do not wish to use hormonal contraceptives.

They are suitable for women who only have intercourse now and again and therefore do not want to use any regular form of contraception.

Disadvantages of the diaphragm and cervical cap

The diaphragm and cap must be inserted each time you have intercourse. If an additional spermicide is used you have to remember to wait long enough for it to become effective.

The methods involve handling the genitals. Some women are uncomfortable about this or find it unpleasant. The methods also take some of the spontaneity out of love-making.

Some women describe an uncomfortable foreign body sensation when using the diaphragm or cervical cap.

The diaphragm and cap can also have side-effects. They can cause vaginal inflammation. Some women complain of more frequent urinary tract infections.

Women with an abnormal PAP smear should not use the cap or diaphragm until the smear is normal again. The methods can cause additional irritation of the cervix, particularly if used in combination with a spermicide.