Hi, I have a quick question for the medical field subject!

I googled this and got nothing that answered me, but i want to know...

How can you tell if someone is bleeding internally? This is going to be in a report for class, and I'd like to know if my belief is correct, or incorrect and if there is a way to tell without a machine.
My belief is, well- you know how bruising begins to form over a day or two? It takes time to show how worse it is, depending on how bad it is. Well my assumption is that a bruising like pattern appears on the skin, in large sections.

If I'm wrong please tell me! If you know other ways also share! Please!