Contraception and the prevention of sexually transmitted diseases
Kirkman, R.; Chantler, E.
British Medical Bulletin 49(1): 171-181
1993
ISSN/ISBN: 0007-1420 PMID: 8324607 Document Number: 328748
Spermicides kill a wide range of bacteria and viruses causing sexually transmitted diseases (STDs), including the human immunodeficiency virus (HIV) in vitro, and protect in vivo from infection by gonorrhoea, chlamydia, and pelvic inflammatory disease (PID). In the UK and the US, the most commonly used compound in spermicidal agents is the neutral surfactant nonoxynol-9. Although spermicides reduce the incidence of reinfection by some STDs, an in vivo virucidal action is not supported by convincing data. Among barrier methods, latex condoms provide an impervious barrier in vitro to most STD pathogens, including HIV. Natural condoms made of sheep intestinal membrane can allow passage of hepatitis B viral particles but not HIV in vitro. Several studies have shown protection against cervical gonorrhoea and PID among diaphragm users; however, diaphragm use has been associated with an increased rate of urinary infection and also bacterial vaginosis. It is conceivable that women using oral contraceptives (OCs) do not develop as much tubal damage as women not using OCs because of a modified immunological reaction. A study carried out in Europe showed a statistically significant protective effect against PID of the levonorgestrel-containing IUD as compared with the copper-containing Nova-T. A case/control study of 1028 women in Chicago in 1970 noted admission for PID during the following 7 years of only 1 woman who had been sterilized compared to 9 controls. A case/control study examining risk factors for cervical intraepithelial neoplasia (CIN) in 103 women with biopsy-confirmed CIN II or III did not find an increased risk with either OC or IUD use after adjusting for other known risk factors. After adjustment for age and education, the odds ratio for diaphragm use was .3 and the odds ratio for condom use was .5. Thus, hormonal contraception and tubal ligation give protection to the upper genital tract but not to the cervix.