Multiple forms of barrier methods are currently used: male and female condoms, the diaphragm, the contraceptive sponge, and cervical cap. Vaginal barriers are easy to use and are non-invasive. They can be used with little advance planning. Consistent and correct uses are absolutely essential for barrier effectiveness; most failures occur due to improper or inconsistent use. The 'typical use' pregnancy rate for these methods can be as high as 20-30%. The male condom has a 'typical use' failure rate of 14%. Recent studies have shown that teens were most likely to use condoms for birth control and 66% used a condom when they became sexually active (151).
Mechanism of action: Both the male and female condoms provide a physical barrier that prevents sperm and egg interaction. They are intended for one time use only. Condoms also provide some protection against HIV and STI.
Diaphragms and cervical caps use two different mechanisms, a physical barrier as well as a spermicidal chemical. They are available by prescription only, and must be sized by a health professional for a proper fit. They are always used with spermicidal agents. Diaphragm provides protection for 6 hours and cervical cap for 48 hours after insertion.
The contraceptive sponge is a disc shaped poly urethane device and contains a 1,000 mg of nonoxynol-9. It does not require prescription, and provides protection for up to 24 hours after insertion. The typical use pregnancy rate for this method is 10-40%.
Vaginal barriers have many advantages: protection against sexually transmitted infections provides immediate protection without much prior planning, easy access, and no systemic side effects. Disadvantages include: discomfort with placement and use, possible latex allergy (for condoms), increased incidence of urinary tract infections and bacterial vaginosis; and associations have been reported with toxic shock syndrome. In addition, a health care provider may be required to do the initial fitting for diaphragms, necessitating an extra visit to the physician's office. A comparison of the ability of contraceptive methods to reduce sexually transmitted disease is found in table 8.
Table 8. Effectiveness of Contraceptive Methods: Pregnancy Prevention and STD Protection
|
Contraceptive Method |
Effect on Reproductive Tract |
Effect on Bacterial STDs |
Effect on Viral STDs |
|---|---|---|---|
|
Diaphragm/Cervical cap/Sponge |
Reduces risk of PID; associated with vaginal and urinary infections |
Some protection against cervicitis; increases organisms associated with bacterial vaginosis, candidiasis and urinary tract infections |
No protection against vaginal infection or external genitalia transmission; prevention of HPV controversial. No protection against HIV |
|
Female condom |
Occasional local irritation |
In vivo protection against recurrent trichomonal infections suggests possible protection against other STDs |
In vitro impermeability to cytomegalovirus, HIV |
|
IUD |
Foreign body reaction within the uterus; |
Copper IUD: No protection LNG-IUS: associated with decreased upper-gential tract infection |
No protection |
|
Latex male condom |
Occasional latex allergy |
Protection against most pathogens in genital fluids |
Less protection against organisms transmitted from external genitalia (HSV and HPV) |
|
Combination oral contraceptive |
Increased cervical ectopy; decreased risk of symptomatic PID requiring hospitalization |
No protection against bacterial STDs; possible increase in cervical chlamydia |
Data on HIV transmission risks conflicting; role regarding risk of HPV infection and cervical dysplasia unclear |
|
DMPA/ Implants |
Atrophic endometrium; thickening of cervical mucus |
Assume no protection |
May promote HIV transmission |
|
Spermicide with nonoxynol-9 |
Risk of chemical irritation of vaginal epithelium/alteration of the vaginal flora with high doses |
equivocal |
Data suggests increased HIV transmission risk |
|
Tubal ligation |
Changes associated with surgery |
No protection |
No protection |
|
Contraceptive Vaginal rings |
Increased Vaginal discharge in some users |
No protection |
No protection |