Why does the body bleed so little during surgery?

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I mean, I get a little nick from a knife while chopping vegetables and I fill up a small bowl with blood… but these guys are doing open heart surgery and theres barely any blood at all.

Why is that?

In: 4

They are trained at keeping it cleaned up so they can do the surgery. Typically patients are giving several “units” of blood during a surgery to make up for the loss. How much loss depends on the surgery obviously.

Well I dont know for sure so dont take what I am about to say as fact but I would assume they know where the veins are and try to either leave them intact or like stop the veins up so they dont gush blood

I work in hospitals and the operating rooms.

Surgeons are adept at minimizing blood loss through speed and efficiency. There are also many tools, such as tourniquets for limbs and cauterization tools (which seal cut vessels) to minimize blood loss. Additionally surgeons know where to cut to avoid vessels that will cause significant bleeding.

I’ve seen joint replacements where the patient loses less than 250 mL / 8 oz of blood. This is well within the body’s ability to replenish without undue stress.

They cut super carefully, avoid veins if possible, clamp things closed, etc. There’s just a ton of little careful things that add up to not leaking much blood.

One: The body isn’t just a sack full of a blood. It’s a closed system where you only seriously bleed if you severe a major artery. Surgeons are trained not to cut arteries unless necessary.

Two: A lot of surgeries begin with a local injection of epinephrine, which constricts local blood vessels. This means that the local area doesn’t bleed much because the vessels are not flowing fully.

Three: If the surgery requires a blood transfusion, the transfusion will include the clotting factors that lead to clot formation. This means that your blood is primed to stop bleeding.