Condoms, caps and diaphragms

New products and techniques may help improve the popularity of female barrier methods of contraception.

According to the poet Antoninus Liberalis, things were pretty wild in the royal family in ancient Crete in 1500BC.

King Minos had married Pasiphae, the daughter of the sun god Helios. He did not, however, let marriage interfere with his dalliances with numerous mistresses.

A jealous Pasiphae responded by conceiving a hybrid child, the Minotaur, with the king’s favourite bull.

When this made no difference to the king’s indiscretions, she put a spell on him so that his semen contained poisonous scorpions, snakes and millipedes, which promptly killed his lovers.

Pasiphae, being an immortal, was immune to the spell and became the only woman with whom he could safely have intercourse.

But there was a catch. Although intercourse was not a problem, the insect-laden ejaculate was unsuitable for conception and the couple remained childless.

It was suggested that Minos insert a goat’s bladder into Pasiphae’s vagina prior to intercourse, which would collect the fatal semen. The couple were then instructed to have intercourse immediately afterwards without the bladder and Pasiphae became pregnant at long last.

It is not recorded whether Minos employed the same trick with his other lovers.

The story is an interesting one in that it encapsulates so many of the issues faced by couples throughout the ages — infidelity, sexually transmitted bugs, contraception and infertility.

It was also the first recorded use of female barriers.

Related: Barrier contraceptives

The female condom
The female condom is a strong, soft, transparent, pre-lubricated sheath, which is inserted manually into the vagina before sexual intercourse.

The original version was made of polyurethane, but since 2009, most female condoms have been made of nitrile, a synthetic rubber that is latex-free. This is the version available in Australia.

Nitrile is cheaper than polyurethane, has minimal allergy potential and produces less rustling noise during use than the previous polyurethane version.

Female condoms made of vanilla-flavoured latex, silicone, polyethylene and even the original polyurethane are also available in some parts of the world.

Female condoms provide good protection against STIs, although perhaps slightly less than male condoms.

The standard female condom has a flexible ring at each end. The inner ring at the closed end is used for insertion and helps keep the device at the upper end of the vagina. This ring is removable. The larger, thinner, outer ring remains outside the vagina when the condom is inserted. It anchors the condom so that the sheath covers the external genitalia as well as the base of the penis during intercourse.

With perfect use, the annual failure rate is estimated at 5%, but the typical failure rate is perhaps more telling — around 21%.1 As with other barrier methods, people don’t always use female condoms consistently and correctly. Correct use requires:

  • Carefully removing the device from its packaging so that it is not damaged
  • Squeezing the inner ring between the thumb and middle finger
  • Inserting the inner ring high into the vagina
  • Ensuring that the outer ring lies snugly against the vulva
  • The penis should be guided carefully within the condom.

Female condoms are less constricting for the male partner and have the advantage of not having to be placed immediately prior to intercourse. However, they are more expensive than most male condoms and they can be somewhat hard to find in Australia. There are now a number of online pharmacies and specialty suppliers that sell a pack of three for around $12-$20.

Diaphragms and caps
A diaphragm lies diagonally across the cervix, vaginal vault and much of the anterior vaginal wall. A cervical cap is applied to the cervix itself and held there by suction.

Unlike condoms, there is no way that either can promise a ‘sperm-tight seal’, and it is likely that both act primarily by reducing the numbers of sperm transiting through the cervix to the uterus. This would statistically reduce the risk of pregnancy in much the same way that males with a low sperm count may have more difficulty achieving a pregnancy.

When used with a spermicide, there may be the additional effect of retention of the spermicide close to the cervical os, where it is likely to have the most impact.

A diaphragm or cap may be inserted any time before sexual intercourse, but must be left in place for at least six hours after intercourse.

It is recommended that diaphragms remain in the vagina for no longer than 24 hours without being washed and dried, although this can be extended to 48 hours in the case of a cervical cap.

In the 1950s, around 12% of couples in the US used a diaphragm or cap for contraception. But by 2002, that figure was down to about 3%. Rates of use in Australia are even lower, with the most recent national contraceptive survey, in 2003, indicating it was the choice of only 0.9%.2

Why such low popularity?
Even with perfect use, the failure rates of female barrier methods are significantly higher than those of the pharmaceutical methods developed over the past 50 years.

Failure rates of diaphragms and caps range in the literature to anywhere from 6-26%.3 This is obviously greatly influenced by whether they are used consistently, as well as the inherent characteristics of the couple using them: age, underlying fertility, frequency of intercourse, etc.

There are, however, some undeniable advantages to diaphragm use — the main ones being a low side effect profile, immediate reversibility and that the method is completely under the woman’s control.

Another reason for the low popularity of female barrier contraception in the past was the need for the device to be individually fitted. Clinicians required a set of fitting rings, and both training and experience to ensure the best fit.

This is no longer the case for modern cervical barriers, and perhaps the lack of any requirement for fitting and refitting will make it more generally acceptable to women in whom high efficacy is not a priority.

What diaphragms are available?
Since 2016, there has been only one diaphragm available in Australia — the silicone Caya. It comes in only one size, which fits most women — more than 90% in one recent  trial.4

This puts the discussion and provision of the diaphragm squarely back into the province of general practice, where it most appropriately sits.

It is, however, still recommended that a clinician checks that the woman has placed the device correctly over the cervix before she relies on it for contraception. It should not be recommended before six weeks after vaginal delivery or where vaginal muscle tone is really poor.

The Caya looks somewhat different from a conventional diaphragm. It is lavender in colour for a start, and has raised dots at the side to make insertion easier. It also has a special ‘hold-point’ at the front to aid removal.

Caya efficacy studies were conducted in conjunction with a companion lactic-acid-based gel. The manufacturers recommend that around one teaspoon of the gel be applied to the upper surface of the device prior to insertion. The gel tastes like something between lemon and vanilla. This can be an important consideration for couples for whom oral sex is part of their sexual repertoire.

In the most recent efficacy trials, Caya and gel used together had a typical failure rate of 18%.4

The Caya diaphragm is sold by all family planning clinics, and most pharmacies can order it from the supplier. The cost is around $85 for the device and $27.50 for the gel.

The device lasts for up to two years, but the gel has a recommended shelf life of only three months once opened.

What caps are available?
Cervical caps are not marketed at all in Australia, though women can access them through online retailers.

The most easily obtained is the silicone FemCap. Individual fitting is not required since the FemCap comes in three standard sizes based on the diameter of the cervix: 22mm (never pregnant), 26mm (previous pregnancy of any duration but no vaginal delivery) and 30mm (post-vaginal delivery).

As with a diaphragm, it is still recommended that a clinician check that the woman is placing the device correctly over the cervix before she relies on it for contraception.

The FemCap resembles a miniature sailor’s hat. The dome sits snugly over the cervix while the surrounding brim adheres to the vaginal walls by suction. It has a strap attached to aid easy removal.

The failure rate is similar to that of the diaphragm, and the cost is around $100 plus postage from the distributor in the UK.

Conclusion
There are undoubtedly faster and more convenient methods of transport than the bicycle, but it still represents the best option for many people. Similarly, female barrier methods may be a suitable choice for women where contraceptive efficacy is not the prime consideration. The fact that they no longer require individualised fitting removes another obstacle to their use.

Dr Foran is a sexual health physician and coordinator of undergraduate and postgraduate courses in women’s health at the University of NSW.

References

  1. Trussell J. Contraceptive failure in the United States. Contraception 2011; 83:397-404.
  2. Richters J, et al. Sex in Australia: Contraceptive practices among a representative sample of women. Australian and New Zealand Journal of Public Health 2003; 27:210-16.
  3. Guillebaud J. Contraception: Your Questions Answered 5th edn (6th edn linked). Churchill Livingstone, London, UK, 2009.
  4. Swartz JL, et al. Contraceptive efficacy, safety, fit and acceptability of a single-size diaphragm developed with end-user input. Obstetrics & Gynecology 2015; 125:895-903.