Order of orifices: Sequence of condom use and ejaculation by orifice during anal intercourse among women: Implications for HIV transmission

Background: For women, the order of penile insertion, condom use, and ejaculation by orifice during sexual events affects the probability of HIV transmission and design of HIV prevention methods. Methods: From October 2006 to June 2009, 431 women in Los Angeles and Baltimore in a rectal health study reported the sequence of penile insertion, condom use, and ejaculation by orifice location by computer-assisted self-interview. Multinomial logistic regression identified predictors of condom use by orifice among women who reported vaginal intercourse (VI) during their last anal intercourse (AI) event. Results: Of the 192 reporting on a last AI event, 96.3% (180/187) reported VI. Of these, 83.1% had VI before AI. Including the 36% who ejaculated in both the rectum and vagina, 66% report any ejaculation in the vagina and 45% in the rectum. One-third used a condom for both VI and AI, <10% for VI only or AI only, and half used no condoms. After adjusting for race, partner type, and substance use, compared with women who used condoms for both VI and AI at last AI, being older (units = 5 years) [adjusted odds ratio (AOR) = 0.76; 95% confidence interval (CI): 0.60 to 0.96], with serodiscordant partners (AOR = 0.22; 95% CI: 0.08 to 0.61), and HIV-positive with seroconcordant partners (AOR = 0.15; 95% CI: 0.04 to 0.54) were associated with not using condoms. Conclusions: For most of the women in our study VI accompanied AI, with AI usually occurring after VI. This evidence for use of multiple orifices during the same sexual encounter and low use of condoms across orifices supports the need for a multicompartment HIV prevention strategy.