system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can’t a patient’s blood be reused in cases of internal bleeding?

Let’s assume someone has internal bleeding - maybe a ruptured spleen or some such. Could the internal blood that’s escaping be collected, and then used to “top up” the patient’s blood supply when the cause of the bleed is corrected?
gpt
Yes. It's called a cell saver. The blood is suctioned out of the surgical field; washed, filtered, and centrifuged; then transfused back to the patient. It takes some time to set up, but it can save you using a few units of blood.