why the suicide scars?

Wondering about that a bit myself.
I suppose it's possible that his brain is fumbling together various pieces of information as he lies there: his guilt, his grief, his knowledge of impending death or at least severe injury.

Its also possible that he had some kind of personal experience with suicide in the "real world", although I did not notice any mention of that.
Then its also possible that she has a scar in the "real world", which his unconscious mind is trying to make sense of in some way that seems plausible.. but again, didnt notice anything like that in the relevant scenes.

All in all Im not quite satisfied with those answers Ive come up with.. why the focus? why lines such as "do you know what it feels like to hate your life so much, that you bring a backup razor?" ..
From what I gathered, it seemed like "real world"-Henry was not depressed or suicidal, nor hating his life..

_____
I don't know, Butchie, instead.

the only thing i can think of is that lila, as a partial representation of himself in his dream (the painter), attempted suicide because henry is also choosing death, choosing not to fight for his life, choosing not to stay. and like with dream lila, there is nothing sam can do about it.

It's a late reply. However, I interpreted the movie with a whole different approach. I think Sam got affected ( maybe PTSD ) after Henry dying in the accident and that he couldn't save him, this is very burdening and difficult especially to a doctor. So maybe the whole movie was how Sam reacted to everything after the accident, maybe anything sad or difficult made him too stressful and as a result he had memories of the accident and began to suffer day dreams and hallucinations and so on. The other interpretation is that Henry didn't die after the accident and he someway made it and began to go to counseling after that, but this interpretation is so flawed because then , Sam would have recognised him.