How long does it take to correctly type and match a blood type?

My question originates from this thread about tattoos..

Someone mentions that in an emergency they’re gonna slap O Neg into you until they match it, anywhere from a 30 minutes to a few hours later. Someone else mentions it’s as simple as a ph test, where you dip litmus paper into the blood and compare it to a chart.

So for a hypothetical situation, if I’m in a car wreck, and have a piece of my fender sticking out of my shoulder, and part of the license plate in my leg, how long would it take you to give me my own blood type? What’s the “field expedient” procedure (if there is one), what do they do in the ERs around the country (what I would call one step above ‘field expedient’), and what do they do when they have some time to do it carefully?

Genuinely curious on the procedure, but I’ve already been typed O+.

I’ve seen places that say they can do it in 30 minutes.

And being O + won’t protect you from possible complications if you have red blood cell incompatibility, Tripler. Granted if you really need whole blood immediately they’ll just dump O - into you, but it’s much better to get all those other factors matched up, and avoid the not uncommon minor serum sickness, or even a major reaction despite having your major factors match.

Hmph. On CSI they’d already have your blood type, DNA profile, criminal history, parentage and will have plausibly but incorrectly accused you of murder because by an astonishing coincidence you have a motive and no alibi but that’s okay because they’ll find the real killer in the last two minutes anyway.

We did this years ago in my 9th grade health class. It took less than 5 minutes.

Various students volunteered their blood, putting a small cut on their finger, and squeezing a drop of blood onto a glass slide. [All with the same blade, just dipped in alcohol between uses. That experiment would probably cause a dozen lawsuits today!]

Then we used 2 different solutions, A-reactant and B-reactant. If the blood reacted to the A-reactant only, it was type A. If it reacted to the B-reactant only, it was type B. If it reacted to both, it was type AB. If it reacted to neither, it was type O.

And the reaction was obvious – within a few seconds, the blood started to clump up and looked curdled, even to the naked eye. Under a microscope, it was even more obvious.

Probably one of the few lessons I still remember from that many years ago!

With time for a commercial break, too.

“Typing” with anti-A and anti-B serum can indeed be done in a matter of minutes, but you might not want your life to depend in such 3-minute results. There is a lot more to blood typing than just A and B. “Matching” (or “cross-matching”) as we call it in Boston area hospitals, is actually quite a bit simpler, because it checks for reactions between a recipent’s blood and a donated unit (usually, they seal create small samples by sealing them in 1-2" sections in the tubing attached to the bag, so the unit can be tested against a 2nd, 3rd or 4th donor, if it doesn’t match the first intended recipient)

However, a T&C is generally allowed to react longer than the bare minumum, just in case, and even so that isn’t the main reason for the delay. At least when I was in med school, a unit of blood was never defrosted unless there was a pretty good chance it would be needed and would match. (That’s where the blood-filled tubing sealed every couple of inches comes in: each section could be cut, thawed and tested relatively quickly, without thawing the unit it was attached to.) It takes about half an hour to gently thaw a unit of blood and bring it up to transfusable temperature.

Blood can be fragile stuff. Every first-year learns that even something as simple as a) pulling too firmly on the syringe plunger when taking a sample; 2) running a 10K or marathon; or c) using a very narrow needle (common in pediatrics) can cause red cells to rupture and produce lab/clinical abnormalities such as overly high potassium levels (there’s a lot more potassium inside a red blood cell than outside it) Even the hemoglobin released from lysed (burst) red blood cells can be very toxic to the kidneys, especially in a patient who isn’t in he best medical condition to begin with.

Blood is a complex organ, and the lipid bilayer cell membranes of the cells are particularly vulnerable when cols It needs to be treated with respect and gentleness if you want it to do its job well – or even safely. You can’t exactly microwave it. You have to not just thaw it but bring it to at least room temperature and give it time to slowly adjust to its new temperature before you send it squeezing through those capillaries.

What do I care if a unit can be T&C’d against a patient’s sample in under 10 minutes, if the unit itself won’t be ready to transfuse for close to half an hour?

Yeah, what he said.
I love KP’s answer too.

Many years ago when I was a third-year resident in a charity hospital in Brooklyn (and therefore in charge of major decisions involving the blood bank late at night, egad) we were down to three units of O-negative left when an O-negative young man came in bleeding out of multiple gunshot wounds. I made the command decision to release O-positive blood to him. Aware of the possibility of crossmatch reactions – after all, we the residents were the ones sent out to investigate and deal with crossmatch reactions - but, then, I doubted much of the blood we transfused into his body would stay there for long. He was going directly to the OR and, in my opinion, directly from there to the morgue. (Or maybe he made it. I don’t remember.)

Acquaintance on surgery paged me and asked me why the O-positive blood?

I said, “Because we’ve only got three O-neg units left, and if we get in an O-neg woman who needs transfusion tonight, your young man can’t get pregnant.”

Surgery resident thought it over and said, “Okay.”

QtM and KP get it. (I’m talking about Rh disease and hydrops fetalis)

This is coming to you from within the walls of a large teaching hospital in Massachusetts. I work the overnight shift too, where we see a good share of emergency gun shot victims and other such traumas. So Tripler, let me give you the straight dope from the laboratory perspective, just in case you were ever shot after somehow finding yourself in the middle of a Beacon Hill gang war.

Generally in an emergency we can have a cooler of packed red blood cells ready in a little under 10 minutes from the call it is requested… whether or not you’re actually in the facility or racing here in an ambulance is of another matter. The emergency department will generally open a ‘trauma pack’ which instantly gives you an anonymous name and medical record number so we can begin working on you as quickly as possible by expediting all that registration bologna and going straight for the life saving. A good example would be to explain that on arrival the patient already has labels ready to stick on all the lab specimens drawn and they can get them upstairs for testing ASAP.

When a doctor needs blood before we are able to crossmatch we generally send down however many units they request along with a waiver slip, so that it is acknowledged that we have not tested this patient yet. We will always send down type O units, but not always Rh negative. We will try to send O- units as often as possible, but our inventory and the size of the order requested can be a factor. In general women under the age of 60 and children will always get O-, but if we’re in short supply and you’re a male over 40 you might not be so lucky. But that’s just the gamble we have to take considering that you have an 85-90% chance that you’re going to be Rh+ anyways.

Once we are actually able to receive a specimen for the patient it takes about 30 minutes to complete routine testing; this includes registering the specimen in our computer system, spinning to separate plasma and cells, the typing (which we can do in <3 minutes), and then the screening for unexpected antibodies. The screening is the longest process, and this looks for antibodies against a red cell other than the Anti-A and Anti-B in type O, A, + B patients.

But assuming you don’t have these unexpected antibodies (I’ll leave it at that), then **Qadgop the Mercotan ** was right, 30 minutes. Though the only thing I will disagree with was his terminology of transfusing “whole blood”. The Red Cross (the largest collector of blood in the country) separates their collected units into separate components. Remember hearing a Red Cross ad where they tell you that one unit can save up to 4 lives? That’s because the blood collected can be split into a unit of packed cells, a unit of plasma, a unit of plasma cryoprecipitate, and a unit of platelets. Whole blood transfusions are generally limited to autologous units these days.

KP’s answer was very good, except that red blood cells are not routinely frozen and unfrozen. That is only the case with units with very rare phenotype (a collection of rare negative antigens, or a patient who is has Bombay phenotype). And it’s not so easy as just letting the units sit out and thaw. The freezing process involves a glycerolization technique, where a solution is added to a unit and this protects the red cell membrane from the freezing that would normally hemolyze the red cells. And after the units are thawed (no, still no micro waving) we must deglycerolize the units with a technique of multiple saline washes.

If you would like any cite’s or specific clarification into any further procedures just let me know.

Cool. Is it possible for a non-medical person to obtain the reactants for an at-home test?

thanks, bigbabysweets! That’s a masterful summary!

And you’re right, hardly anybody transfuses whole blood anymore! My bad.


Google took 2/3rds of a second to find this sponsored link:
Home Blood Type Kit
Do you know your blood type?
Find out in minutes at home

No doubt there are other companies selling these serums also.

Wow! I want to thank all of you guys for the input! I was under the impression it only took something on the order of fifteen minutes flat in all cases, but now I can understand why it takes a little time.

Here’s another few questions from a neophyte: Why does everyone seem to prefer to send O Neg? Given the law of supply and demand, I can understand rationing it, but what also makes it so special for women and children? A lower chance of ‘body rejection’?

And just one more: I’ve seen a few war movies (and yeah, I know they’re not exactly medically accurate), with a few guys giving direct transfusions: donor connected to an IV to the reciever on his own IV, and a long tube between 'em. Does this ever happen? What’s the safety ramifications for doing it either in the hospital or on the battlefield?

Genuinely curious, sanguinely-minded. :smiley:

I just want to get to the bloody bottom of my curiosity.

Yes, because it works for everyone.
So if you have a seriously injured person, and don’t have the time to determine their blood type, O Neg will work for them without reactions. So you can get some blood into them quickly, and then take the time to type their blood, and give the matching type for later transfusions.

In pregnant women, you have to worry about both the mother and the unborn child – they can be different blood types. The “universal donor” O Neg type will work for both of them.

*Here’s another few questions from a neophyte: Why does everyone seem to prefer to send O Neg? Given the law of supply and demand, I can understand rationing it, but what also makes it so special for women and children? A lower chance of ‘body rejection’? *

All right, so here’s the simplest way I can think to explain it. There are hundreds (maybe more) of blood types. By this I mean the antigens on your red blood cell wall (we’ll keep HLA antigens and white cells out of this). But for the sake of blood typing and finding compatible blood we only do a routine ‘type’ for the ABO and Rh blood groups. Although we think of someone as A+ or O- or AB+, these are in fact two completely different blood antigens unrelated to each other (AB/O/A = ABO type, -/+ = Rh type).

Now your body will naturally make antibodies against the A and the B cell phenotype, i.e. if you’re a type O you will naturally have anti-A and anti-B, or if you’re a type B you will have only anti-A, and if you’re type AB you will have neither. This is what makes type O blood compatible with everyone. Now as far as the +/- though, the Rh group is the second most common group we type for. And although we designate someone as + or -, the Rh group consists of several antigens, the +/- is just what we know as the ‘D’ type. Rh actually consist of D,C,c,E,e, and many more antigens. The Rh phenotype is very complex, and fills up a ton of medical journals. The point that I was trying to make is that we just type for the D part of the Rh, and your body doesn’t naturally make antibodies against it. You must be stimulated into making antibodies against it just like you would against any other foreign antigen (like a vaccine) by being exposed to it. So if you’re O-, you are not likely to have any reaction the first time you are transfused with O+ blood.

Why we care if you’re a woman of childbearing age: Basically you NEVER want to give a woman Rh+ blood if you don’t know her type because of fears that she will develop an Anti-D antibody. This is a very clinically significant problem if she has a child with a man who is Rh positive and the child is then born Rh positive. This leads to hemolytic disease of the newborn (I love wiki).

Why we care if you’re a kid: basically, it’s purely sentimental… basically we just want to conserve as much O- as we can, but clearly if our inventory is enough we will tend to want to use the O- units. Being a child just makes us want to prevent the child from making an antibody more because, well, he’s just a kid. (I say he, because girls/women would fall under the category of never transfusing someone of childbearing age with Rh-positive units)

And just one more: I’ve seen a few war movies (and yeah, I know they’re not exactly medically accurate), with a few guys giving direct transfusions: donor connected to an IV to the receiver on his own IV, and a long tube between 'em. Does this ever happen? What’s the safety ramifications for doing it either in the hospital or on the battlefield?

I’m answering this with the equivalent of a bump, because I really don’t know. The closest example of this I can think of was a semi-recent incident in El Salvador that had our Blood Transfusion Service (BTS)(modern name of blood bank) buzzing.

To leave you with a final thought, although we, the BTS the doctors and the nurses, do all we can to make an emergency transfusion safe, there always carries a risk. There can be many types of reactions other than the ones involve having the blood being compatible. And even compatibility issues as well. A recent incident that comes to mind (although trauma ID’s are confidential, I am still using false ones) was when we had a young male gunshot victim come in early in the morning with an unknown identity. He was given a trauma name of TRAUMAMALE HDL, and the emergency department requested 4 units uncrossmatched. I can’t recall if we sent O- or O+, but it didn’t matter, once we got a sample and tested it as quickly as we could we identified an Anti-Kell antibody for another less common blood group. It turns out that this patient was later identified as a male who we had admitted under similar circumstances over 3 years ago for a stabbing wound. He developed the Anti-Kell antibody at that time making some of the units of blood incompatible. That patient did not live, though I don’t think it was directly related to the transfusion.