Why are some bruises yellow some are green, purple, blue, red… why is that??? I know what a bruise is but why the variety of colors??? :dubious:
I believe that is the color of the blood as it is broken down and reabsorbed by the body. I had one spectacular bruise that covered my entire left tricep, except it wasn’t actually a bruise and didn’t hurt at all. I had torn a muscle in that area while wrestling and it bled a pretty good amount before stopping. The blood all pooled there and it took months before it was all reabsorbed.
From here:
Does this help?
“There are two major breakdown products that can lead to visible color in a bruise. These are a green pigment called biliverdin and a yellow-brown pigment called bilirubin. Bruises usually start out as a dark blue or crimson; fade to violet, green, and dark yellow; then turn a pale yellow; finally disappearing completely.”
from http://www.drbunn.com/bruise.htm
My experience is consistent, that bruises change color over time. My most spectacular bruise occurred a few years back when I was dropped really hard on my ass during martial arts (BJJ). When I woke up in the morning, I was surprised to have discoloration on the front of my leg near my groin. When I went to the doctor he asked how I slept. When I told him on my stomach, he told me the internal bleeding had drained downwards while I slept.
For a couple of weeks the bruise on my groin changed shapes and colors pretty spectacularly.
I always wondered why I don’t bruise. I used to when I was a kid, but I haven’t had one in 20 years or more. I can hit myself hard on the arm hard but no bruise ever appears.
Some people seem to bruise with every little bump against something.
And there doesn’t seem to be a direct correlation between the severity of an impact, the resulting pain, and the ugliness of the bruise. Quite often I’ll notice a nasty looking bruise, and will have no idea how I got it, and it doesn’t even hurt. Whereas other times I’ll bang myself and think, “That’s gonna leave a mark,” only to be surprised when no bruise develops.
My wife used to get really upset at the bruises I’d develop doing martial arts. Generally the obvious bruises were superficial, and did not correlate with what I perceived as the more serious injuries. But it was pretty ugly when someone would just grab or strike you in a certain manner such that you ended up with a perfect imprint of his fingers or entire hand somewhere on your body/neck.
Maybe you’re a superhero. 
Well there was that radioactive marmont that bit me. 