From what I've came to understand, it's the most risky and effecting thing you could do to yourself involving unprotected sex... I suppose, more likely than pregnancy from vaginal sex without a condom.

Anyway, is there any certain approach to getting through a session of anal sex without a condom and also stay confidently clear from picking up an STI or other? (Like an extensive washing beforehand?)

Also, I figure I don't have good chances from the very beginning, but could you get an estimate... in a percentage, for how likely it would be to pick up an infection from ten minutes of anal sex.