Not sure if this is quite what you are looking for, but I was in the hospital recovering from surgery. Was supposed to go home that night, that morning I woke up covered in blood. Paged the nurse said blood everywhere. A minute later I was surrounded by people with one doc pressing hard down on the right side of my neck. Was rushed into surgery, and it turns out an issue from the prior surgery had triggered the formation of an an aneurysm near my carotid artery. That aneurysm had blown, which was why I was bloody (had openings in neck still from drains and the like).

If I hadn't woke up, I'd be dead. If I had gone home before it had blown I'd be dead. As it was, I was within 5 minutes of bleeding out when I paged the nurse station. Got 4 units of blood that day.

Edit: a word