Blood transfusion

How it saves lives

Lose enough blood and the body can no longer carry oxygen to its organs, and death follows fast. For centuries there was nothing to do about it. Transfusion replaces what is lost, but early attempts often killed, because mixing incompatible blood makes it clump. The discovery of blood groups explained why, and made it possible to match donor to patient safely. Add ways to stop donated blood from clotting and to store it, and a hospital can keep a supply ready for the moment it is needed.

The story

Before the twentieth century, a haemorrhage, from childbirth, an accident, or surgery, was often simply fatal, and doctors could only watch. The turning point came in 1901, when Karl Landsteiner worked out that human blood comes in incompatible types, which is why some transfusions saved lives and others killed. Once blood could be matched, stored and shared, whole fields of medicine opened up: major surgery, safe caesareans, cancer chemotherapy, and the treatment of trauma all depend on a supply of donated blood. There is no tidy figure for the lives it has saved, because it works in the background of almost everything else, but modern medicine could not function without it.