How scary is blood, really?
July 10, 2009 8:32 AM   Subscribe

How scary is blood, really?

I was curious how safe and/or possible it is to draw blood without causing serious harm or death? Is it possible to see blood on the skin without the plausible threat of death? If so, what methods exist for doing so without fatal harm to the individual?

I am asking this mostly out of curiosity of my own body, and of the human body in general.
posted by anonymous to Science & Nature (29 answers total) 5 users marked this as a favorite
Cut your finger. It will only hurt for a minute, it isn't at all likely to cause death and is not itself serious harm, and you'll see blood on your skin.

(I have a feeling this isn't really what you're asking, but your question is phrased strangely.)
posted by OmieWise at 8:36 AM on July 10, 2009

Most health fairs have folks with those little prick devices like this to draw blood for measuring, say, glucose levels. Each device is thrown away after being used once. Is that what you're asking?

My most frequent encounter with my own blood is when I brush my teeth too vigorously.
posted by vacapinta at 8:36 AM on July 10, 2009

People bleed and not die all the time -- surely you have!?
posted by fritley at 8:38 AM on July 10, 2009 [2 favorites]

Oh, yes. Very superficial, clean, easily-healed cuts and punctures can draw blood with basically no harm other than the obvious risks one takes from skin breaks. Think acupuncture and other small-gauge needles, and very light scalpel or razor cuts.

What is your question exactly?
posted by fiercecupcake at 8:38 AM on July 10, 2009

You could (and should) donate an entire pint without doing any harm to yourself.
posted by IanMorr at 8:39 AM on July 10, 2009

Most cuts, scratches, and scrapes will cause some blood to be on the skin, and none of those things cause death (maybe if they get badly infected.) Even a stab wound needs to be in the right place for death to be an issue.

Again, maybe that's not what you're asking though? Perhaps email a mod to follow up to clarify your question.
posted by ferociouskitty at 8:39 AM on July 10, 2009

(Or, you know, get a kitten, since that's how I'm seeing the most blood lately. Tiny needle talons...)
posted by fiercecupcake at 8:40 AM on July 10, 2009 [2 favorites]

It depends on how much blood you're drawing. You could put small cuts all over your entire body and be no worse for wear.

If you cut into a serious artery or path of blood you start running into a higher rish of death\permanent injury.
posted by zephyr_words at 8:40 AM on July 10, 2009

There's actually a kink community who is into bloodplay and blood fetishism. They have all sorts of gear for messing about with blood. For me, chewing on the occasional hangnail or picking the occasional scab is usually enough blood for me. Plus you know, the menstrual thing.
posted by jessamyn at 8:40 AM on July 10, 2009

I'm a little puzzled by the question... people bleed routinely and it doesn't mean death. Women generally bleed monthly. I bleed sometimes when my parrot bites me. You can bleed from a very shallow scratch in the right place.

Whether or not something is life-threatening depends on the injury, not the presence of blood.

Or are you asking about infection? Even then, it doesn't really have anything to do with blood, or how much of it, just what you do with the wound afterward.

Could you clarify what you're asking?
posted by Nattie at 8:40 AM on July 10, 2009

The red cross sucks many gallons of blood out of donors every year. They always need new donors.

I think you need to revise your question and message a mod. Do you mean for a layperson to perform a transfusion?

Throughout my childhood I've been covered in blood without a minor threat of death. Without clotting factors a small cut could be dangerous, but healthy blood will stop the flow from an injury.

FWIW IANAH (hematologist)
posted by JimmyJames at 8:42 AM on July 10, 2009

As vacapinta mentions above, there are many people who draw their own blood for glucose testing every day (I'm one of them). The only people who have to be "scared" of minor cuts are hemophiliacs, and even then there are effective treatments.
posted by Halloween Jack at 8:47 AM on July 10, 2009

Something in the post made me think of blod injury phobia, a condition in which the sight of blood, even superficial wounds, makes the affected individual significantly upset, physically ill, or causes them to faint. Despite the name, it is in a slightly different pathological category than other more "traditional" phobias like fear of snakes or heights. (IAMNAD)
posted by Jon_Evil at 8:48 AM on July 10, 2009

I'm also puzzled by this question. How much of this is about visceral perception and expectations?

When I worked at a lab, I would give blood for research use. They'd do draws of 50-100ml.

At once point the tech almost dropped one of the sample tubes. It occurred to me that even though 50ml wasn't all that much blood (I probably have ~3000ml in my body, and blood banks take 450ml), it would have been shocking to see that volume it spattered on the floor.
posted by Good Brain at 8:51 AM on July 10, 2009

How scary is blood, really?

Not scary at all! It's coursing through all the living humans and animals right now, keeping them alive! It carries oxygen throughout their bodies!

I was curious how safe and/or possible it is to draw blood without causing serious harm or death?

Extremely safe, as long as you don't cut into major vessels! And as long as you're not a hemophiliac, which is a dreadful disease that affects some humans.

Is it possible to see blood on the skin without the plausible threat of death?

It certainly is! Here's a way to do so: Find a consenting human, and ask them if you can give them a small poke with a needle. You'll see a tiny drop of blood well up from the wound, about the size of Abraham Lincoln's forehead on a standard American penny coin. Then, clotting factors will close up the wound, and the blood will stop coming out. Just make sure you don't make a big hole in the human's skin!

If so, what methods exist for doing so without fatal harm to the individual?

You can use a small pin or needle, as outlined above, or you can use a knife, which is a flat piece of metal used for cutting things. Humans have been using these for thousands of years to cut each other, exposing blood to the air! Again, though, if you want to do this, make sure the human consents to it, or they will become extremely angry.

Good luck!
posted by Greg Nog at 9:16 AM on July 10, 2009 [38 favorites]

How scary is blood, really?

Not scary at all! It's coursing through all the living humans and animals right now, keeping them alive! It carries oxygen throughout their bodies!

One aspect in which blood is scary is that it is possible to spread certain diseases through blood. Generally its advisable to avoid contact with other peoples' blood for this reason, although since that kind of contact is rare anyway it's usually not a problem for most people.
posted by burnmp3s at 9:26 AM on July 10, 2009

There are a number of blood-borne diseases, notably HIV/AIDS. If you mess with anybody else's blood, or expose others to your blood, there is some risk of infection with any blood-borne pathogen.

I got a bad case of poison ivy, and have scratched my skin to the point of minor bleeding from scabs pretty frequently this week, and I'm f
posted by theora55 at 9:39 AM on July 10, 2009

Its getting infected thats scary. You can lose a fair amount of blood, but you really dont want to infect the wound.
posted by damn dirty ape at 9:40 AM on July 10, 2009

I'm really, really confused about this question. Is it a joke? Or was something lost in translation?

Original poster, I wish you would email one of the mods and amplify your question.
posted by Sidhedevil at 9:56 AM on July 10, 2009

I guess you aren't a woman, or you would have encountered your own blood during menstruation, and would have noted that you can regularly shed lots of blood and tissue without any ill effects.

I have noticed that some men are more squeamish about the sight of blood, perhaps because they aren't as used to seeing it or dealing with it as women are. Maybe you are trying to get over your fear of seeing it, because blood=injury=possible death?

If you aren't a hemophiliac, the sight of your own blood should not be scary.
posted by vickyverky at 10:07 AM on July 10, 2009

Lots of people self-harm with razor blades for long period of time, drawing large amounts of blood without dying. So: yes it's possible to both your questions. Pins, needles, razorblades, whatever can break the skin for the other question.
posted by beerbajay at 10:49 AM on July 10, 2009

How scary is blood? That's a personal answer, to a large degree. Some people faint at the mere sight of it. On the other hand, I don't consider it a big deal at all.

Last summer, we got an air conditioner that my wife's toddler nephew had stuck a few things into, and I had to repair it so that it didn't make obscenely loud noises when we run it. I took it apart and was in the process of repairing it when I noticed blood smeared all over it. Turns out that I'd run my fingers over the vanes in the back that dissipate heat, they're quite thin and sharp if you're not careful. My reaction was one of "oh, how inconvenient, let me clean the AC off. My wife (financee at the time) freaked out, "OMG you're bleeding!"

Really, it was just the equivalent of a few papercuts (well, 22 across 8 fingers), but I didn't even feel it.

Your own blood is perfectly safe to you, and if you're a healthy person, your immune system should be pretty robust. I wouldn't go sticking myself with dirty needles, but my usual reaction to a cut or scratch is to let it clot, and then leave it alone. Excessive washing seems to slow healing time.
posted by explosion at 10:59 AM on July 10, 2009

In a wilderness setting, a person can lose up to about 25% of their blood and survive for a while just fine. (depending on the person, the temperature, the diet, etc etc etc.)

You tend to go into hypovolemic shock around 30-50%. Really the mechanics of going into shock are pretty amazing in my book. You take a deep breath (think right before impact) to superload get tingly because your blood sucks to your core, your brain dumps adrenaline, your body tenses to mitigate damage, your pupils dilate, and your heartrate increases as your body tries to superload 02 for the impending peril.

Then everything slows down. Respirations. Heartbeat. As you continue to lose blood, your vasculature does everything it can to mitigate blood loss while preserving your most vital organs. Extremeties go first, then non-essential major organs. Obviously brain is last, heart and lungs right before that.

That was my favorite part of becoming a WFR, learning the physiological reasons behind our bodies doing what they do.

Other than that...blood's pretty harmless. Air kills most stuff pretty fast. Especially HIV/AIDS. That's why the blood inside used needles is more dangerous than the blood outside needles. Platelets and cells die fast, really really fast. That's why when you give blood it never hits air...air and blood aren't friends. Your ... red blood cells? I forget...see air and go OH SHIT BLAMMO and do everything they can to aid in clotting. That's why you see big pools of blood that are all clotty and yucky, because that's the blood doing what it does...trying to stay inside, even though it's too late. Some early AIDS treatments involved cycling your blood out of your body, exposing it to sterile air, and putting it back inside you...but it didn't work because you can't get all your blood out of all your tissues to expose it to least not at once...

I might have some minor details a little screwy in there, but that's the general gist. You can lose more than 25% and survive just fine...but with increased loss comes a greater immediate need for emergency medical care.

Here's a fun fact! You can "bleed out", (bleed to death) internally in 3 places. Your chest cavity, your abdomen (firm abdomen after a fall or car wreck? time to go to the ER!), and inside your upper thigh @ your femoral. That's why, to me, a broken femur is one of the scariest possible accidents..but pulling traction on them is kinda interesting.
posted by TomMelee at 11:35 AM on July 10, 2009 [8 favorites]

Maybe you are asking how much blood you can lose before you die?? About 3-5 pints according to googling, but please don't try that at home -- not a doctor.
posted by Houstonian at 11:37 AM on July 10, 2009

Is this a question about why people faint at the sight of blood? The answer is probably often a vasovagal episode, which I have personally experienced many, many times. I 100% understand that having a small vial of blood taken won't kill me; having a bunch of them taken won't kill me. Doesn't make a difference when I'm having it done.
posted by transporter accident amy at 12:26 PM on July 10, 2009

How scary is blood, really?

It really depends of where its coming from.

Also, I don't really understand what you're asking. Instead of having people guess what you mean, why don't you clarify you inquiry by emailing a mod?
posted by ob at 12:36 PM on July 10, 2009

what methods exist for doing so without fatal harm to the individual?

Well, the way I did it a couple of months ago was to break a vase and slice open my left wrist, severing my radial artery and a couple of tendons (gory pic from the ER). I bled a remarkable amount in the 30 seconds or so before someone handed me a bar towel and I could twist it around the wound, but by the time I got to the ER the artery had stopped bleeding and the doctor closed up the wound and sent me home with a referral to a surgeon to reattach the tendons. I was never in immediate danger of dying, even though I lost a couple of pints of blood.
posted by nicwolff at 3:14 PM on July 10, 2009 [1 favorite]

My Leukemia was first discovered when I went in for something completely unrelated, and a routine blood test showed that I had a hematocrit (ie., the proportion of blood volume that is occupied by red blood cells) of 11%.

An average woman has a hematocrit of 38%, and they begin blood transfusions at 24%. The next day, I was given six pints of blood--never felt so good in my life.

In short, I felt absolutely crummy, was at death's door, but truly thought the extreme exhaustion was due to flu (as I've never had the flu before).

I wouldn't recommend it, but I guess it is possible to live with anemia. At least for a few weeks.
posted by litterateur at 6:08 PM on July 10, 2009

This may help with the presumed question about how much blood we have.

That link uses fake blood, but it will rock you like the real thing. (I hope.)
posted by Lesser Shrew at 6:18 PM on July 10, 2009

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