What are the most effective 'sperminators'?

Although condoms are popular, there are other barrier contraceptives, ie caps, diaphragms and spermicides.

Caps and diaphragms fit inside the vagina, covering the cervix. Vaginal diaphragms are shallow, circular dome-like devices made of thin, soft rubber with a flexible rim. Cervical caps are smaller and thimble-shaped, some of which are made of silicone.

Caps and diaphragms are personalised for individual use and should not be shared with friends. It may not be suitable for women who do not feel comfortable touching their private parts.

The cap or diaphragm has to be used with a spermicide. The effectiveness is enhanced if used correctly and consistently.

The failure rate of the cap and spermicide in women who have not given birth varies from nine to 20 per cent, ie nine to 20 women in 100 will get pregnant in a year of use. The failure rate in women who have given birth varies from 26 to 40 per cent, ie 26 to 40 women in 100 will get pregnant in a year of use.

The failure rate of the diaphragm and spermicide varies from six to 20 per cent, ie six to 20 women in 100 will get pregnant in a year of use.

When used alone, the failure rate of spermicide varies from six to 26 per cent, ie six to 26 women in 100 will get pregnant in a year of use.

The cap or diaphragm is less effective if it is not used every time there is intercourse; it is not of the correct size; it does not cover the cervix; it is damaged (torn or has holes); intercourse occurs three hours or more after insertion and extra spermicides are not used; extra spermicides are not used every time there is more intercourse; it is not left in the body for six hours after the last time there was intercourse; or oil-based products (lotions, oils or some pessaries) are used with the cap or diaphragm.

If any of these events occur, emergency contraception is advisable.

Advantages

Almost all women can use caps or diaphragms. It is only needed when one wants to have sex and can be inserted at a convenient time before sex.

However, extra spermicide is required if the cap or diaphragm has been inserted more than three hours before sex. There are no health risks or side effects from the use of caps and diaphragms. The woman is in control of her contraception.

The use of spermicide is simple and convenient, especially after one learns how to use it. It has no effect on the body's hormones and can be inserted as part of foreplay.

It is easily available and does not require a prescription, and can be used during breastfeeding.

Disadvantages

Caps, diaphragms and spermicides are not as effective as other contraceptive methods, and provide only limited protection against sexually transmitted infections (STIs). It may take some time to learn how to use them, and may affect the spontaneity of sex.

In addition, the latex of the cap or diaphragm may lead to irritation in some women and their sexual partners.

Caps and diaphragms may not be suitable for women who have a cervix that is of unusual shape or position, or if the cervix cannot be reached with the fingers; weakened vaginal muscles - usually as a result of childbirth, which cannot hold the cap or diaphragm in place; allergy to latex or spermicides; repeated urinary tract infections; current vaginal infections; and previously had toxic shock syndrome or increased risk of STIs.

Spermicides may cause irritation to the vaginal skin or penis, and rarely, an allergic reaction. This problem can be averted by changing brands.

Some people perceive spermicides as messy or have an unpleasant smell or taste.

Spermicides do not protect against STIs, including HIV/AIDS. It may increase the risk of HIV/AIDS in women at risk and who use these products often, because it may cause disruption of the surface of the vagina and rectum.

Caps and diaphragms

It may take some time to learn how to fit a cap or diaphragm correctly. Advice and instructions on its use are easily available from doctors or the local family planning clinic.

The insertion can be done in a position that best suits the individual - squatting, lying down or standing with one foot on a chair.

About a third of the cervical cap has to be filled with spermicides, and its sides squeezed and held together by the thumb, and the index and middle fingers. The cap is then inserted into the vagina to fit over the cervix, which feels like the end of the nose.

The cap stays in place by suction. Additional spermicides are then inserted.

After putting two strips of spermicides on each side of the diaphragm, the index finger is put on its top and it is squeezed between the thumb and other fingers.

The diaphragm is then inserted into the vagina in a downward and backward direction to ensure that it covers the cervix. It can be inserted dome up or down, whichever is easier.

It is important to check that the diaphragm covers the cervix. If the cervix is not covered, the diaphragm is taken out and re-inserted.

The cap and diaphragm have to be left in place for at least six hours after the last act of intercourse. It can be left longer, but a rubber cap or diaphragm cannot be left in for more than 30 hours. The silicone caps can be left in for longer, depending on the type.

If used during menses, the cap or diaphragm has to be removed six hours after the last act of intercourse. Removal is easy, with the finger gently hooking under the rim or loop, and then pulling downwards.

After removal, the cap or diaphragm has to be washed in warm water with a mild toilet or baby soap, rinsed and let to dry, and then kept in its box in a cool dry place.

It should not be boiled; neither should disinfectant, detergent, powder or any oil-based product be applied to it. Silicone caps vary. Some need to be washed, whereas others can only be used once.

It is advisable to check for tears or holes before use, by holding it up against the light and having a good look. Sometimes the cap or diaphragm gets discoloured or out of shape. This does not make it less effective so long as there are no tears or holes.

Caps or diaphragms can be used after childbirth or miscarriage, but a different size may be needed. It is recommended that they are used six weeks after childbirth, but they can be used soon after a miscarriage.

Spermicides

Spermicides contain a chemical that destroys sperms. Nonoxynol-9 is the most commonly used. It is available as films, creams, gels, pessaries or sponges, and can be purchased over the counter from pharmacies. They are generally used with caps and diaphragms. They can be used alone or with other contraceptives to increase their effectiveness.

Spermicides are inserted deep in the vagina shortly before sex. They prevent pregnancy by blocking the cervix and immobilising the sperm, thereby preventing the sperm from meeting an egg.

It acts by altering the integrity of the sperm's cell membrane and the vaginal pH, creating a hostile environment for sperm.

Spermicides increase the effectiveness of barrier contraceptives. They also provide lubrication and places contraception under a woman's control. However, there is no evidence that condoms lubricated with nonoxynol-9 are more effective in preventing pregnancy than condoms not lubricated with it.

It is not known whether the contraceptive effectiveness of nonoxynol-9 differ with different formulations and doses.

It is important to read, understand and adhere to the instructions on the package insert before using the spermicide, as each form is used slightly differently. If the spermicide is not used as instructed, its effectiveness will be decreased.

The spermicides can be inserted gently deep into the vagina with an applicator or the fingers when squatting or lying down. The insertion has to be done 10 minutes before intercourse for many forms of spermicide that are available.

The spermicides are usually effective for an hour after insertion. Additional spermicide has to be inserted on each occasion there is vaginal intercourse.