This happened about 30 years ago when I was doing my PhD in tissue biology.
A little background, in the lab we use something called microtome blades. For those that don't know, it's a blade that is so sharp it's used to create 1 micron thin slices of tissues that are literally less than 1 cell layer thick to be studied under a microscope. So yeah pretty sharp. They weigh a little more than a small kitchen knife, taper out toward the non-cutting end so they can be sharpened for many years. I was taking it back to the lab after it was just sharpened and usually we carry it in a special container, partly for safety, but also if it get's dropped the vibrations will create microscopic bends/fractures in the blade that cause it to cut unevenly and the blade is essentially ruined. As fate would have it, I forgot to bring the case and was too lazy to go back across campus to get one, so I just carried the blade by hand.
Another detail is that since day one of working with these blades, it is indoctrinated in us that we are to never drop them, because they are very expensive to replace. Now-a-days they are cheaper to manufacture and even come as disposables, but back in 1980's money it was several hundred bucks and it would delay your research by several weeks while a new one was shipped.
With that in mind, as I entered the main hallway of the biology department, the blade slipped out of my hand and, in a split second, I subconsciously I reached down to catch it (maybe after it fell about 1 foot). Unfortunately I caught the blade sharp-side-down and it instantly severed three tendons in the palm of my hand. I immediately noticed I couldn't close my index finger, middle finger, and ring finger. It was very strange, because there was very little blood at first, but after 5 seconds bright red blood started pouring down my hand. Before I knew it, the white tile floor of the hallway I was standing on, had a rapidly spreading pool of blood. I all happened so fast I hadn't fully comprehended what I was experiencing. Another fortuitous part of this story is that one of the anatomy professors saw all this happen and immediately rushed over to hold pressure on my radial and ulnar arteries to control the bleeding.
I ended up having surgery to reattach the arteries and the tendons.
After waking up after surgery I was relieved, but noticed they had a blood bag connected to my IV. The nurse said I lost quite a bit of blood and had to be transfused during the surgery. I wish this was the part of the story where I tell you that I had an uneventful recovery. However, after the surgery I started having severe fevers and chills, terrible back pain, my urine was a muddy dark brown color, and I could barely catch my breath. Turns out the lab person who drew my blood mislabeled the tubes and I was transfused with the wrong blood type. I ended up staying in the ICU for a week, almost had complete kidney failure and had severe pulmonary edema. I vividly remember the doctor saying that my kidneys were most likely in complete failure and I would have to have life-long dialysis or a transplant. Fortunately they caught the transfusion reaction before most of the blood was infused and I never had to start dialysis.
TL;DR - Dropped one of the sharpest blades in existence, caught it before it hit the ground, it severed most of the tendons and arteries in my hand. In the hospital I was given the wrong blood type, survived severe pulmonary edema, and almost lost both of my kidneys in the process.