More inaccuracies. Anal sex does not automatically transmit an STD in the vagina just by going from the anus to the vagina. Bladder infection yes, but not the infections we recognize as traditional STDs, i.e. gonorrhea, chlamydia, herpes, etc. Those pathogens have NOTHING to do with anal>vaginal sex, or going from one hole to the other. If they were present in the man BEFORE SEXUAL CONTACT WITH THE WOMAN, then they can be transmitted, no matter what hole was penetrated. The way you have it worded here is very misleading and not factual. Without a preexisting infection, anal to vaginal sex can really only cause a bacterial UTI from the e.coli or a very nasty vaginal infection known as BV, or bacterial vaginitis. These things can easily be avoided by being clean and using the body parts only in the place they were designed to be used!