Eli5 why is it that if I cut myself with a knife I bleed like crazy, but when a surgeon cuts into a chest, removes the ribs to perform a major surgery you don’t see all that much blood comparatively?
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Ooh ooh I know this one having spent a little time in the OR. The skin on much of your abdomen and chest isn’t brimming with blood vessels like your fingers. And what you don’t see maybe is that someone is standing by with cautery to quickly zap any bleeders. Also they may have put in a local anesthetic that includes a second drug that shrinks the blood vessels in that area. It turns out using local nerve block reduces stress even though they are also using a general anesthetic.
I once tripped and a stick jammed itself through my leg skin. Like all the way in under the skin and then all the way out like a giant sewing needle. No blood. My dog does this too. He’ll go crashing through the brush and have like a huge tear in the skin. One time I saw his muscles moving! Took a bunch of stitches but zero bleeding
Because surgeons use tools that cut and cauterize at the same time. The cauterizing seals blood vessels shut and minimizes blood loss.
Also, a suction machine is used during surgery. It sucks the blood away from the surgical field and it goes into a reservoir in the machine. So the surgical field remains relatively bloodless.
Source: I’m an OR nurse.
Some good answers already about cautery and other techniques to minimize bleeding
I will add that sometimes we do surgery and it’s horrifically bloody. Liters of blood loss. More than the patient’s entire blood volume, especially in kids since they don’t have much blood to begin with
I’m a scrub nurse in theatre.
We use tourniquets for limb surgery. We use electricity to cauterise tissue/small vessels. We temporarily clamp major vessels. We use clotting agents (both IV like TXA and direct wound agents like Floseal). We use harmonic instruments to either dissect or fuse tissue which is less traumatic.
TL:dr, we have shit tonnes of options to decrease bleeding.
Two reasons, one someone is constantly stuffing your insides with super absorbent gauze to mop up the blood.
The other factor is that someone will be in charge of cauterising the blood vessels which involves “burning” the exposed vessels causing them to plug up, kinda like how you burn the ends of nylon rope after cutting it to melt the ends and stop it from fraying
There are some almost-correct answers here.
There isn’t “someone standing by” to cauterize.
Instruments that both cauterize and cut like plasmablade are relatively rare.
It’a not just someone sopping up blood.
The more complete answer has multiple parts:
1) Surgeons know where to cut to avoid any significantly sized veins or arteries. Anatomic variants exist, but in general they avoid going through these vessels.
2) Skin is usually cut by the surgeon with a scalpel. Then they use a cautery tool to cauterize and bleeding. They wipe/dab with sponges to see where the bleeding is coming from and zap it.
3) Fat, fascia, and organs are usually “cut” with the cautery tool. It’s not really cutting, it’s burning at a higher power to both cauterize and break the tissue.
Source: I’m an anesthesiologist and spend a lot of time watching surgery, and have participated in hundreds of surgeries in medical school.
I work in a hospital.
Sometimes the operating theatres look worse than horror films after surgery.
1. When we put you under general anaesthetic your blood pressure drops so you’re not pumping your blood round your body as hard and it oozes/bleeds less. Slow moving bleeds clot, so little bleeding vessels don’t even need cautery. If your BP goes up during the op, the surgeon will give the anaesthetist a “yo bro, slow the flow” look before continuing because the bleeding increases and it’s harder to see and get a grip on things.
2. Choosing where to cut to avoid major vessels
3. Cautery
4. Clamps for larger vessels. We can stitch them closed too if they’re damaged.
5. In some operations they can even block the blood flow completely by clamping off arteries or blowing up medical balloons inside the vessel further upriver
I’m not a surgeon or a doctor but I work with one. I work with an ENT surgeon, and I assist her with procedures in office. For excisions, she injects a numbing medication with epinephrine, which helps to slow or minimize bleeding in that local area. I suction or blot any active bleeding, she cauterizes active blood vessels. Similar is done with many surgeries in the OR.
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