My cat has blood around his . What could that mean?

After using the the litter box doing a #2, (do do, not trying to be funny), i noticed my cat had blood around his . I wiped it off and it doesn't appear to be bleeding more. He does drag his on the carpet. The vet said he doesn't have worms and hee drags his frankly because it felt good to him. what do you think this blood could mean?