Prevalence and types of rectal douches used for anal intercourse: results from an international survey

Anal intercourse (AI) without condoms represents one of the most efficient modes of sexual transmission of HIV [1] and is a risk factor for the transmission of other sexually transmitted infections (STIs). A number of studies have raised concerns about the potential for rectal products used with AI to facilitate transmission of STIs including HIV. The COL-1492 trial provided evidence that vaginal application of Nonoxynol-9 (N9) was associated with increased risk of HIV infection, and further studies showed that rectal administration of N9 was associated with sloughing of rectal epithelia [2‐4]. Furthermore, in vitro and animal studies have demonstrated that some commercial lubricants may damage rectal tissue [5‐9]. In a clinical study, lubricant products caused short-term denudation of rectal epithelium, which was suggested to be induced by the lubricant’s osmotic effect on the rectal mucosa [10]. Cell contact with hyperosmolar solutions (like many lubricants) can cause cells to dry up and collapse. Such injury of the rectal epithelia has been hypothesized to enhance the probability of transmission of pathogens such as HIV [10] and other STIs. In addition to biologic plausibility, a recent epidemiologic study demonstrated that lubricant use during AI was independently associated with rectal STIs [11].

Other practices that may affect the rectal epithelium and enhance STI/HIV transmission include the use of rectal douches and enemas. Vaginal douching has long been associated with a number of STIs, such as chlamydia and gonorrhea [12‐15]. Likewise, a number of studies have demonstrated an association between the use of rectal douches/enemas and HIV [16‐19], though data on the association with other STIs is limited, with one study showing an association with Lymphogranuloma venereum (LGV) proctitis [20] and another with Hepatitis B virus (HBV) [21]. A recent survey of men who have sex with men (MSM) in the United States found that 44-53% reported rectal douching before last receptive AI [22], with the prevalence as high as 64% in the past 6-months [18]. Additionally, a study among Peruvian MSM found that 27% reported a history of rectal douching [23]. However, little is known about the specific content and types of douches used. Because the prevalence of rectal douching may be relatively high and the products used may cause damage to the rectal epithelium, the contribution of this practice to the transmission and acquisition of STIs including HIV may be important.

The objective of this study was to examine specific content and types of products used for rectal douching among men and women (including both commercial and non-commercial, “homemade” products) and to evaluate rectal douching practices and factors associated with douching. We hypothesized that there would be variation in both commercial and “homemade” products used for rectal douching and that factors associated with rectal douching would vary by age, gender, and sexual behaviors. We further hypothesized that rectal douching would be associated with self-reported STI status including HIV.

Based on this internet survey, we found that a substantial proportion of respondents reported rectal douching before receptive AI with a non-trivial proportion reporting rectal douching after receptive AI. These findings are consistent with the small number of studies conducted on this topic and suggest that rectal douching with AI is a relatively common practice [18, 22]. However, our study is one of the first to report on the content and type of rectal douches used for AI. While water enemas – the most commonly reported product in this study – are hypotonic and have fewer reported complications when compared to hyperosmolar enemas, they have been associated with rectal epithelium loss and damage when compared to isotonic solutions such as polyethylene glycol [24‐27]. Likewise, colonic irritation, colitis, and rectal epithelium damage has been noted with some of the other products used for rectal douching including water and soap, sodium phosphate enemas, and laxative-based enemas (e.g., bisacodyl) [24, 28, 29]. Given that the most commonly used products may cause damage to the rectal epithelium, this practice may increase the risk of transmission and acquisition of STIs/HIV. Furthermore, these findings suggest that harm reduction strategies recommending products that minimize rectal epithelial damage may be warranted.

Our finding that douching varied by region is supported by the small number of rectal douching prevalence studies [18, 22, 23] as well as other studies on rectal practices surrounding AI such as lubricant use [30] and may reflect variations in sexual practices by region. Indeed, in exploring reasons for lack of rectal douching by region we found that in regions where the prevalence of rectal douching was low such as Asia, reporting that ‘Didn’t know people used an enema or douche for anal intercourse’ was far more common than regions where rectal douching was high (53% in Asia vs. 17% in North America, p value < .01; data not shown). Consequently, the impact of any harm reduction strategies to reduce the use of potentially harmful products may be more relevant in regions where this practice is more pervasive.

We also found that the prevalence of rectal douching varied by a number of sexual risk behaviors including substance use. Specifically, more substance users reported rectal douching as compared to non-users. This may be partly explained by evidence which suggests that substance use, in particular methamphetamine use is associated with prolonged sexual encounters, including an increase in number of events with casual or anonymous partners [31]. Moreover, certain substances including opioids increase the likelihood of bowel dysfunction and constipation, potentially increasing the need for rectal douching [32‐34]. Beyond sexual risk behaviors, rectal douching was also associated with sexual health outcomes including HIV. Our finding that rectal douching was more prevalent among those who are HIV-positive is supported by a number of studies that have shown that HIV-status is associated with rectal douching [16‐19]. Furthermore, our results indicate that a history of STIs in the past year, including rectal chlamydia, gonorrhea, and syphilis was also associated with rectal douching even after adjusting for potential confounders such as condom use, substance use with sex, and HIV-status. This not only adds to the small number of studies which have noted an association with rectal douching and non-HIV STIs including LGV and HBV, but also lends epidemiologic support to the hypothesis that rectal products used for anal intercourse may facilitate transmission of STIs.

Rectal douches/enemas may serve as a possible delivery mechanism for rectal microbicides, which are currently under development [35]. Findings from this study add support to the promise of the acceptability of this delivery method, given that the behavior is already commonly practiced before receptive AI [36, 37]. Of note is our finding of the association between rectal douching and other behaviors associated with risk of acquisition of STIs/HIV, such as substance use that suggest use of HIV prevention via rectal douches may fit into the repertoire of those most at risk and when engaging in their riskiest behaviors. Furthermore, our findings that the prevalence of douching is higher in the context of casual partnership including one-time and anonymous partnerships, as well as serodiscordant partnerships, suggest that those most at risk or during periods of greatest risk are also most likely to practice douching. These factors along with the potential for the improved safety profile of a rectal microbicide over existing commonly used products, suggests that douches could hold great potential as delivery mechanisms for event-based methods of prevention. Given past challenges with adherence to topical microbicides [38, 39], another delivery method that is part of the behavioral repertoire of many people who engage in AI may enhance acceptability and therefore, adherence.

A number of limitations related to this study should be noted. The survey respondents represent a convenience sample drawn from a larger population of users of the targeted email lists, chat rooms, and websites and it is unknown what proportion of subscribers completed the survey. This limitation of online sampling has been previously noted; however, the strength of this method is the ability to access hard-to-reach groups and eliminate some of the validity issues associated with interview-based data on sensitive sexual behaviors [40, 41]. Furthermore, interpretation of the association between STIs and rectal douching is limited by the fact that STI status is based on self-report and includes events occurring in the past year, while rectal douching practices relate to those reported for the past 3 months. However, evidence that rectal douching behaviors may be pervasive and start at a young age increases the likelihood that practices in the past 3 months may be indicative of rectal douching practices overall [18].

In summary, rectal douching for receptive AI is common and because rectal douching was associated with other sexual risk behaviors, the contribution of this practice to the transmission and acquisition of STIs including HIV may be important. While further longitudinal studies may help to further delineate associations between STIs/HIV and the different rectal douching products used, this study provides important information for the promotion of better rectal safety and rectal health.