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

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

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 tell me! if you know other ways also share! !