I don't know of any completely safe way to have anal penetration but if that is the only way to experience satisfaction then people will keep doing that. One of the most common problems people have is hemorhoids and irritation will cause bleeding. The smooth surface of a condom and lubricant will help some and salves such as Prep H will help with the itching and irritation. Best to read up on this condition as it can cause serious problems later on.