Lu T, Mao X, Peng E, et al. - Per prior works, rectal douching (RD) is linked with HIV acquisition among men who have sex with men (MSM). Researchers here examined the precise mechanism underlying the link between RD and HIV. They recruited 1,365 participants over WeChat from October 2017 to October 2018 and mailed HIV self-testing kits to them. Participants uploaded images of HIV self-test results and completed an online electronic questionnaire simultaneously. Among these participants, 39.93% (545/1,365) reported RD in the past 6 months, 60.07% had multiple male sexual partners and 43.08% had condomless anal intercourse (CAI) in the past 6 months. Based on self-testing, HIV was prevalent in 3.37% (46/1,365). Analysis confirmed the correlation between RD and HIV; CAI and rectal bleeding were identified mediating HIV infection in Chinese MSM who douched. They recommend encouraging strategies to strengthen health education and decrease high-risk sexual behavior in order to lower the risk of HIV in MSM who use enemas. They suggest rectal microbicides to be an efficient means of providing HIV prophylaxis among MSM.