My mother spent entire night at the hospital. She stayed up late making my birthday cake. I assume she got tired and cut her hand accidentally. Father took her to the local hospital immediately, where they bandaged her wound and gave her medicaments against infection. Doctors also told her that she has lost a lot of blood and has to stay in hospital over night and to receive an infusion. Why was that blood vessel damage in her case has been that big?
She probably cut one of the superficial arteries in hand. You must realize that there is a great difference between arteries and veins. While arteries carry oxygenic blood, veins carry blood with carbon dioxide. Blood in arteries is under much more pressure than blood in veins, therefore, when blood vessel damage appears in artery, blood can leak out very fast. If, for example, carotid artery is cut, person can die within few minutes. Fortunately, your mom was in a completely benign situation.