Diaphragms and caps

This factsheet by the fpa explains how diaphragms and caps work, how effective they are at preventing pregnancy and their advantages and disadvantages.

What are they?

Diaphragms and caps are barrier methods that prevent sperm meeting an egg. They fit inside the vagina and cover the cervix (entrance to the womb). They're made of latex (rubber) or polyurethane (plastic). They come in different shapes and sizes.

Vaginal diaphragms are circular domes with flexible rims. Caps are smaller than diaphragms. To be effective they need to be used with spermicide - a special cream or pessary that kills sperm.

Myth: Only women who've had children can use this method
Fact: Not true - diaphragms and caps come in different sizes and types to suit all women
Myth: You can use them without spermicide
Fact: Not true - to be effective they need to be used with a spermicide

How reliable are they?

Their effectiveness depends on how carefully they're used. They are 92-96 per cent effective when used according to instructions. This means that using either method, between four and eight women in 100 will get pregnant in a year. The silicone cap - Femcap - has a higher failure rate.

How do I use them?

Diaphragms and caps need to be used each time you have sex. Spermicide is applied to the diaphragm or cap, which is then inserted into the vagina to cover the cervix. They can be inserted any time before sex but if it's more than three hours before sex you must use more spermicide.

The cap or diaphragm needs to be left in place for at least six hours after the last time you had sex. It can be left in longer if necessary.

Advantages:

You only have to use it when you have sex
It has no serious health risks
There's a choice of different types
It can be put in at any convenient time before sex
It may give some protection against cervical cancer

Disadvantages

Putting it in at the time of sex can be an interruption
Some people find the spermicide messy
Some diaphragm users find they get cystitis (changing to a smaller diaphragm or cap can help)
Some people are sensitive to the chemicals in latex diaphragms or caps or to the spermicide
Oil-based lubricants such as body oils or lotions should not be used with latex diaphragms or caps

Can anyone use them?

Diaphragms and caps don't suit everyone. They may not be suitable if you:

Have vaginal muscles that cannot hold a diaphragm
Have a cervix of an unusual shape or in an awkward position or you cannot reach it
Have repeated urinary infections
Have had toxic shock syndrome in the past
Do not feel comfortable touching your genital area

Other things to consider

You can buy diaphragms and caps if you know your size
You may need a different size if you gain or lose more than 3kg (7lb) in weight, have a baby, miscarriage or abortion

Where can I get a diaphragm or cap?

They're free on the NHS from contraception clinics, sexual health clinics and from your GP (if your surgery offers contraceptive services). You can buy them from a pharmacy if you know your size.