09 Dec Contraceptive: Barrier Methods
Ask the Lady Doctor – Which contraceptive should I use?
Part 2: Barrier Methods
Our ancestors contrived many “barriers” to copulation and pregnancy. The chastity belt was a very effective, albeit slightly barbaric way for a man to ensure that his woman did not take a lover during her mate’s absence. These contraptions were made of metal and frequently had barbs on them to discourage “intruders”. They had very small openings for urination and defecation and were actually locked with a key. Admittedly, the ultimate goal here was not contraception but that was a happy side effect.
Today, a woman who wants to take charge of her fertility has several choices – particularly when it comes to using barrier methods of contraception. Condoms, diaphragms, vaginal sponges, spermicides and cervical caps all afford a fairly high rate of efficacy against pregnancy along with the added bonus of protecting against STDs (sexually transmitted diseases). They are also relatively free of any risk to the user. However, it is important to realize that diaphragms, spermicides and cervical caps are difficult to obtain in BC and over the past 20 years have gone out of favour.
Condoms have been around for millennia. They are effective, safe and inexpensive. They are also ubiquitous – conveniently located in most public washrooms and in all pharmacies and corner stores. The rate of pregnancy with proper condom use (i.e. with EVERY act of coitus) is about 5-10% (i.e. 5-10 pregnancies per 100 woman years of use). This can be improved with the concomitant use of spermicides.
Latex condoms are airtight and water tight which renders them impermeable to most microbes that can cause STDs. Herpes, gonorrhea, chlamydia, trichomonas, syphilis and HIV cannot penetrate latex condoms (but all bets are off if you are using lambskin!) Since cancer of the cervix is associated with herpes simplex virus as well as human papilloma (wart) virus and chlamydia, the regular use of condoms is also protective against cervical dysplasia (cell changes leading to cancer).
The female condom has been around since the early 90’s but has failed to gain popularity as a method of birth control. Couples have complained that it is awkward to use, unsightly and slippery. One study found that it takes an average of 15 tries before the condom stays in place correctly and doesn’t slip. Further, the female condom is three times the price of the male condom. For a good review of the correct use of this method click HERE.
Spermicide literally “kills sperm”. It comes in a variety of preparations: creams, jellies, aerosol foam and suppositories (both foam and non-foaming). The spermicide acts as a barrier that prevents sperm penetration. The active agents within the spermicide kill sperm and decrease their motility. Spermicides inactivate the enzymes contained in the head of the little creatures so that they can’t penetrate the egg. There are in excess of 100 million sperm in a single ejaculate.
Spermicides are associated with a pregnancy rate of 5-25 per 100 woman years of use. Their effectiveness is related to the couple’s motivation to use them consistently with every act of coitus. They are very safe with no serious side effects. Previous concerns about an increased risk of spontaneous abortion (miscarriage) and congenital defects have NOT been substantiated.
The diaphragm is a dome shaped, latex rubber barrier that must be fitted by your family doctor or gynecologist. It is both a physical barrier and an effective vehicle to carry spermicide. A diaphragm must be left in place for 6 hours following intercourse and more spermicide needs to be used if intercourse occurs again within this time. The pregnancy rate associated with correct use is 5-10 per 100 woman years of use. There is a slight increased frequency of urinary tract infections among some users possibly due to compression of the urethra. The diaphragm is also thought to be protective against pelvic inflammatory disease.
The cervical cap is similar in its effectiveness to the diaphragm. It is more difficult to fit. It, too, must be left in place for 6 hours after intercourse. Unlike the diaphragm, you don’t need to use a spermicide with the cap and you can leave it in place for up to 36 hours.
The vaginal sponge is made of a polyurethane material, which is impregnated (excuse the pun) with nonoxynol 9 (a spermicide). The spermicide is released during coitus. It functions to absorb ejaculate and block the entrance to the uterus. It is effective for up to 24 hrs and is associated with a 10-15 percent pregnancy rate. There is NO risk of toxic shock syndrome with use of the vaginal sponge. Vaginal sponges, spermicides, male and female condoms are available in Canada over-the-counter without a prescription.
For an excellent and more complete review of this topic, please visit JOCG (The Journal of Obstetrics and Gynecology) on line.
In Part 3 in this series on contraception we’ll take a look at the IUD (intrauterine device).
More :
Part-1 : Natural Family Planning
Part-3 : Contraceptive – IUD
Part-4 : Oral Contraceptive Pill (OCP)
Part-5 : Which contraceptive should I choose?
The author is Dr Shannon Lee Dutchyn, MD, CCFP, FCFP, a Canadian physician.
© October 2020.