A bruise shouldn’t affect a tattoo. I would think only a cut requiring stitches would be a problem.

@harlem shake 131787 wrote:

the other day i was out playing sports when my arm hit the gate i was playing around it seems a cut/ bruise formed on it can it be touched up to fix it its not a big mark on it. has anyone one ever got a bruise or cut on their tattoo and how did you make it go away asumining that people here are heavily tattooed in their arms.:(

If you are asking as the title suggests if you you can get it touched up while it has a cut or a bruise then the answer is yes but I would wait until it heals so it is easier on your tattooist.
If you are asking what happens when you get a cut or a bruise and if you will need to get it touched up? Then the answer is : after your tattoo is healed it is normal skin and if you were to get a major trauma to your skin that would scar then it will affect your tattoo. It is skin just protect it from the sun!