Pretransfusion Testing

[Music] hi welcome back to the bloodbank guy video podcast my name is Joe Chaffin it is February 2012 and today we're going to be covering pre-transfusion testing uh this is part two of the basic immunohematology series and we will uh talk a little bit more about that in just a second first though I'd like to I'd like to thank you uh for the comments that you've sent my way regarding the previous podcasts including uh the comments that have come through the bloodbank guy site um especially things like this uh it's nice to know that I stink I appreciate it truthfully not many people have said that but but I enjoy the ones that do uh don't flood me with you stink emails by the way all right so uh also through the Facebook page which is facebook.com/ bloodbank guu um I I'm I get a lot of comments through this page and in fact we just hit a milestone recently uh where over 500 people now quote unquote like hate that phrase the bloodbank guy on on Facebook I just want to remind you if you notice right above the where the 501 uh number is you see bloodbank guy or BB guy Vimeo videos so you can watch these videos actually directly on Facebook if you if you so desire um I also have had a lot of mentions and comments through Twitter uh I'm I'm happy uh very happy to when that happens and a lot of direct messages that people have sent me through Twitter as well so thank you for all of those um with that being said let's move on and talk about the series that I mentioned at the beginning the basic immunohematology series started with the blood groups overview podcast which was recorded and released in December 2011 today is number two the pre-transfusion testing podcast February 2012 um the basic antibody identification podcast will be released either on the very last last day of February 2012 or the beginning of March 2012 um and the advanced antibody ID podcast which there may be more than one of those I'm warning you in advance but certainly at least one will be released later in 2012 we'll we'll announce that as we get closer uh so today what we're going to do with pre-transfusion testing is start with an overview just basically what are we trying to do what's our goal and then second talk about the testing methods that are used in pre-transfusion testing go through those in great detail we've we covered some of that in the basic uh blood blood groups overview section but we'll go into a little more detail this time uh next the components of the process specifically what do we need to do uh in order to get a particular blood product ready for release um from the transfusion service um and then finally we'll hit a little bit of nomenclature just to make sure that you understand clearly some of the terminology surrounding pre-transfusion testing so what are we trying to do when we're when we're doing pre-transfusion testing in other words when we're doing the testing that we are required to do before the a blood product leaves the control of the transfusion service and goes either to a patient in the hospital or to a an outpatient or whatever the case may be is that we're trying to choose the most appropriate blood product from a safe compatible donor and Infuse that product into a properly identified and thoroughly tested recipient basically we're going to spend the rest of our time together today kind of beating that to death and figuring out exactly how to do that as you can imagine like most things in Blood Bank uh pre-transfusion testing is regulated uh Clea sets the minimum laboratory standard for uh blood banks and Laboratories in general and also has a few specific regulations surrounding pre- pre-transfusion testing uh but honestly Clea doesn't tend to inspect Laboratories all that much in particular transfusion Services all that much because there are organizations such as the AABB and the College of American Pathologists that have what's called deemed status meaning that if you success F pass for example an aab inspection you can use that inspection to satisfy the requirements of Clea it's not mandatory that you do so but you can do it um the FDA on the other hand at the bottom um doesn't do a lot with pre-transfusion testing uh there are some things that we'll talk about later in terms of the fda's mandating which antigens need to be uh represented on antibody screen cells but aside from that they're they're not nearly as involved in pre-transfusion testing as they are in the production of the red cells uh or the other components in the blood center here's the big picture and you'll see this uh on the bottom of page one if you notice at the bottom left hand part of your slide you see page one uh written there most of the slides will tell you exactly where we are in the handout if you have not downloaded the handout pause this podcast go to ww. www.bbb.org uh click the podcast Tab and follow the directions to the uh to the handout for this particular podcast anyway so if you notice up at the top there are things that the blood supplier does in terms of testing of the donor um and there along the bottom there are things that the transfusion Ser transfusion service does and we're going to focus primarily today on stuff done in the transfusion service your handout will talk a little bit about what the blood supplier does we're not going to spend a whole lot of time on that mostly the the things in blue this is another way to look at it um from a from an article in in January 2006 basically you we receive a properly labeled esent at the blood bank you do the the testing on the bottom of that of that uh fork in the road antibody screen at the Top If there are no unexpected antibodies and if you determine the the type appropriately then you select an aboc compatible donor unit uh do a Cross Match recipient plasma mixed and centrifuge with sample of donor red cells and then issue the unit that's the general outline of how it's done and has been done for years there's some variations on that that we'll talk about momentarily okay let's go on and talk about the basic reactions in blood banking um the things that we the things that we look for certainly utenation as we talked about in the last podcast is the basic most basic reaction in Blood Bank blood banking it's the coding and then Bridge formation of Red Cell antibodies you see in the Illustrated in the images on the right there's a lot of different things that go into making the coding work better and making the bridge formation happen better and we'll talk about those individually as we go along now hemolysis you should be aware is also actually a positive test test in pre-transfusion testing in fact it's the ultimate positive test uh it's basically direct Red Cell Lis as a result of complement fixation it doesn't happen very often in our testing but it can and remember that it's just as much a positive as a glutin IGM antibodies in particular do that fairly well when we're talking about The Binding of an antigen to an antibody in this case The Binding of a red cell antibody to its Associated Red Cell antigen on the surface of a red cell uh basically it's a chemical reaction and you guys remember chemistry right uh it's been a while for most of you I'm sure but basically an antigen plus an antibody uh has a reversible reaction with an antigen antibody complex and basically what we're wanting to do when we're doing pre-transfusion testing is we want to shift that equation to the right as much as possible in other words we want to see if there is an incompatibility between an antibody and an antigen we want to see that antigen antibody complex stay together so that we can detect it um like most chemical reactions there's a k0 or an equilibrium constant and basically the higher the number for the k0 the more and the more stable reactions there are there's a lot of factors that influence that affinity and and determine how well antigens and antibodies stick together and we're going to take a little while to go through some of those right now the first is thermal range well basically antibodies have a couple different ways of reacting some of them react better either at the immediate spin or 37 degree phase more on that in just a moment and others react better at warmer temperatures the anti-human globulin phase in general the cold reacting ones are are insignificant mm related antibodies with one significant exception and that's in term with but normally those cold reactive IGM antibodies react against carbohydrate antigens like Lewis big ey little ey p m and n the warm reactive antibodies on the other hand are are normally IGG and they're more commonly significant and they're usually reacting versus protein antigens such as the ones you would think of Rh uh Kell antigens uh kid antigens Duffy antigens Etc uh all the things that we talked about in the last podcast second issue that we have to deal with when we're trying to make an antibody and uh an antibody agutin at uh red blood cells is that they the size difference between an antibody and a red cell is spectacular red cells are more than 700 times bigger than antibodies and you can you can think about this this way that if if a red cell was 100 yard long the distance of a the length of a football field so you can imagine that in your brain big old football field size red cell if that were the case then an a single IGG molecule would be about five inches long which is actually smaller than a single football so how is that little guy going to aguate Big honk and red cells well there's a lot of things that we can do to try and influence that among them centrifugation to try and push those two uh push the red cells closer together to make it easy iier for the antibodies to bind I just want to illustrate this for you so we have this image of two red cells sitting there okay there kind of sitting there peacefully and then an antibody comes along and grabs onto them and binds them and that that seems reasonable and we've seen that drawn before but the reality is when you talk about the size difference here's here's how that antibody compares to those two red cells yeah not you can't you really can't see it can you well let's zoom in a little bit it's still pretty darn small so we're really talking about a spectacular uh job for this little tiny antibody to try and bind to two red cells and and and bring them together obviously you need more than one antibody obviously you need a lot of other things going on in order to make that happen better well there's there are some other factors that are kind of fighting against us and that includes electric issues basically red cells have a net negative surface charge due to cic acid residues and those negative charges actually cause the red cells to to repel each other obviously if both if you two red cells are trying to come together and they're both negatively charged obviously electrically that's going to push them apart that's something called Zeta potential and that's a very Elementary explanation of Zeta potential but that's basically what keeps those red cells from getting closer together um Zeta potential applies when two when two surfaces are are both negative and it also applies when they're both positive that you'll see in just a second here's kind of how that looks if red cells are suspended in normal saline remember we have the red cells have that negative surface charge due due to calic acid at the surface if you're talking about normal saline you got a lot of sodium ions floating around and that's those pluses in the top left of the screen well as you can imagine if red cells have a net negative surface charge those sodium ions are going to be attracted and they're going to go and they're going to Cluster around the surface of the red cells ending up with functionally the same thing just opposite charge of a net positive surface charge if if those red cells sorry if that those sodium ions have their way either way with negative or net positive you have repulsion of the red cells um and and that ionic cloud of ions that that surrounds the the red cells can keep those red cells from getting really close together that's Zeta potential again as I mentioned before basically the distance that red cells tend to equilibrate apart from each other as a result of the Zeta potential is about 14 nanometers and ironically that distance that diameter of 14 nomers is as far as a single IGG molecule can can spread uh so you can understand why we'll we'll say just in a minute that an IGG by itself has a difficult time uating red cells it can bind to the red cells but forming Bridges is hard because red cells don't get that close together IGM has a much bigger diameter and of 30 nmet still small relatively speaking but has an easier time doing direct utenation the other thing that you should remember about what happens with normal saline is that antibodies actually at at phes in which we do our testing have a mildly positive uh surface charge so that they can actually bind better to the surface of the that net that negative surface of the antibody well remember we've talked about sodium ions but they're also chloride ions so with normal saline the chloride ions can go and neutralize the antibodies as well so basically normal saline is not the greatest solution to do our testing and that's one of the reasons that we use things like low ionic strength saline now Liss actually has fewer sodium and chloride ions so in the same scenario that I showed you at the beginning there are fewer so positive ions to go and grab onto the surface and so you get less of a of of an ionic cloud and potentially less Zeta potential as a result of that and fewer chloride ions to neutralize those antibodies this is a busy slide that talks about list the the most important facts are found in the second and fourth bullet which is basically that normal Sailing by comparison to low ionic strength sailing Or List normal sailing has about five times sorry about four times more uh more sodium and chloride ions that's that's the bottom line with it so list helps you it helps potentiate reactions as a result of that more on potentiators in just a second now on to pH well pH obviously you know the normal body pH is about 7.4 but most of our reactions that we do in the laboratory react best at a pH of 7.0 7.0 gives you a net negative charge to the red cells and most of the antibodies present have a positive charge so you have a natural attraction there if you go too far down though with the pH you'll actually lead to dissociation uh of a lot of antibodies not all there are certain IGM antibodies such as anti-m that that like to be lower but basically that's one of the ways that we can elute antibodies off the surface of the red cells by dropping the the pH to a lower Point uh next in terms of the factors that influence whether or not uh we're going to be able to do an antibody antigen interaction is the relative concentrations normally in Blood Bank testing we use two drops of serum for every one drop of 2 to 5% Red Cell solution but that's not really hard and fast that's not definite and set in stone you can manipulate it by adding more serum drops and reference Labs do this quite often or using less concentrated red cells to basically increase the ratio of the serum to the red cells or increase the ratio by by direct extension of the antibody to the to the Red Cell antigens you have to be careful with that though there's a phenomenon known as the prozone phenomenon which is Illustrated on the left side of this slide basically when you have too much antibody excess you can be in a position where all the antigen binding sites are taken up by those antibodies uh sorry all the antibody binding sites are taken up and and you end up in a situation where the red cells can't aguate there's nothing left there's no open spots for them to form Bridges um in general there's uh most Blood Bank tests use a a moderate antibody access but not to the extent of of getting to prozone um finally let's talk just a little bit about direct versus indirect utenation we kind of alluded to this before direct utenation is a is a one-step process basically antibody binds to at least two red cells at once in the case of IG and forms Vis and forms Bridges right away that happens much more commonly with IG you can see IGM is a penter IGG is only a monomer um and migm has a a wider diameter can bind to more things obviously 10 binding sites versus two binding sites for the IGG so much more common for a direct antibody sorry direct utenation to occur as a result of IGM interaction IGG on the other hand tends to do inter indirect basically coating the red cells but not necessarily uating and you end up needing another test uh such as an indirect antiglobulin test that we'll talk about in just a moment to determine that the red cells have been coded by the antibody okay we've talked about tube testing before so let's we'll we'll zip through this you remember we talked before about the three phases of tube testing the immediate spin phase the 37 degree phase and the ahg phase let's just show you that graphically because I don't want to look at that slide anymore here's basically how it works so um when we start from the left of the slide uh basically we take a we have a test tube or whatever reagent system you're working with you have a test tube that has antibodies in it or potential antibodies in it you mix those those with red cells you can do it either way you can start with red cells and start with known red cells and look for antibodies or you can start with serum and look for known serum and look for specific uh unknown uh red cells in this case when we're talking about um compatibility testing when we're talking about doing the indirect antiglobulin fa indirect antiglobulin test down the line basically we're using patient Serum with reagent red cells okay so when we're when we're when we're trying to do our test this is what we use we we mix those two together spin them and you look for direct utenation that is the so-called immediate spin phase okay great well once you get to that point you can do well you need to do an incubation um add the your potentiator which can be low ionic strength saline that we talked about before and a couple others that we'll talk about in just a second incubate those at 37 degrees centrifuge again read the read the specimen to look for a glutin that's the 37 degree phase then moving on to the I a or ahg anti-human globulin phase you the first thing you always have to remember when you move from 37° into uh ahg you always have to do a wash you wash to get rid of any Unbound globulins that could uh that could be that could cause a false negative by the indirect Sorry by the anti-human globulin binding and so in over the wash word there you see anti-human globulin which are antibodies against human antibodies uh they binds to coated red cells cause visible utenation and that's the IAT or ahg phase as the case may be potentiators we already said are added prior to 37 degree incubation we already talked about lists we'll say just a couple words about albumin and Peg um and talk about protolytic enzymes later though they're not really a potentiator used in routine pre-transfusion testing albumin um is comes from bovine sources it's 22% concentration basically albumin also reduces Zeta potential in a little bit of a different way um and gives you a somewhat different incubation time Peg or polyethylene glycol is water soluble polymer that by its nature excludes water from around the red cells it helps to decrease that ionic Cloud it helps to basically allow the red cells get closer together um as a result of concentration water moves away red cells can get closer together um the important thing you have to remember about Peg is that Peg causes non-specific auten um at the 37° phase so most Labs that do Peg testing will not even do a 37° phase you certainly have to remove the peg before you go to the indirect antiglobulin phase because you will get non-specific Al glutenins so here's just a slide reviewing how we do this in terms of what what potentiators lead to what incubation times at 37 if you just do saline no potentiator at all you have to incubate for 30 to 60 Minutes well most Labs don't like to do that so they do other stuff like albumin for 15 to 30 minutes or more commonly low ionic strength saline Or List gives you a 15 a 10 to 15 minute incubation much better and the same thing about 15 minutes or so with with PEG that that's kind of an important slide to know so so be aware of those differences in incubation times once you do all this you have to you have to interpret the testing and let's take a look at how tube testing is interpreted here's here's some images that that the folks at imor were kind to give me and I give credit to them thank you very much for that uh basically if you look on the left side of this slide you can see a a very strong single a gluten it at the bottom of the test tube that's a four plus positive on the zero to four plus scale now some Laboratories use a 12o scale 0 to 12 um and that would correspond to a 12 on the 12 scale you move down basically 3 plus and 2 plus you can see the glutenetto the right side of the screen screen you see that the the one plus and the zero plus you actually have a turbid background that's the difference between one plus and two plus by the way is not only the turbid background but larger uat but turbid background corresponds to one plus and again you can see 0 Plus or zero in the 0 to 12 scale no utin it's no visible uten it's whatsoever um I'm not hugely experienced in the 0 to2 scale I have not worked in a laboratory that uses it um there's definitely more options and this shows you some of those options uh this next slide I know this is a little blurry but but you can see that there are variations and increases in strength as you go down this this slide but this starts with zero on the left and moves on to four plus on the right and with the the zero 2 5 8 10 and 12 in the in the 0 to 12 scale again just showing that for your reference all right so gel testing on the other hand is is an alternative to tube testing um that we we covered the very very Bare Basics of it last time but let's talk in a little more detail here basically gel testing is done in little individual individual microw Wells or micr tubes I should say and those tubes contain an actual gel which is a semi viscous solution basically and and that gel in general in in the most common way this is done is impregnated with anti-igg that anti-ig is designed to grab onto uh IGG coated red cells as they go by and and to keep them from going to the bottom of this microtube that's the basic principle of it so so here's how it works you take one of these little mic microt tubes you you add red cells you add plasma um and you incubate and centrifuge the nice thing about gel is that the plasma actually stays at the surface and the the red cells if the red cells presumably coated with antibody uh or potentially coated with antibody they try to they're moved down through the tube as the as the centrifugation happens well obviously there is not only gel in the tube but there's anti-ig so if there are a glenat right away they're going to be stopped somewhat by the gel and if the anti-ig grabs onto coated red cells those red cells are going to be stopped as well basically it correlates uh the distance that the red cells drop down into the tube during centrifugation correlates to how coated they are and here's how that looks if there's if there's no coating of the red cells whatsoever the red cells scoot all the way to the bottom if there is coating of the red cells then they're grabbed at some point along the way to give you a positive reaction and here's a real live look at how how that looks you notice on the left the four plus positive where the red cells are stopped right at the top of the tube and different variations or different levels of Passage through the microt tube on the way down um to a a complete negative on the far right I hope that makes I hope that makes sense gel testing is being used very commonly in the United States and it's it's about it's more sensitive than list test testing in general and about the same sensitivity as Peg testing um a little disagreement on that in different circles but that's how I generally consider it solid face testing on the other hand is also popular as a uh as an automated method primarily but it can also be done uh without the use of automated equipment here's how solid face testing works let me show you this and hang with me here because this is a little difficult to understand when you just look at the results so we're talking about a very small little micro well tiny little micro well size of the your the the nail on your little finger basically so tiny little micro well and on the bottom of those Wells when we're doing our pre-transfusion testing in general what you'll see well you won't see actually because there'll usually be liced red cell antigens on the bottom of that well um they're antigens from a particular donor against which we're trying to test compatibility as part of an antibody screen for example more on that in just a second so you add your patient sample your patient serum or plasma sample as the case may be that if there is incompatibility if there's an anti body against one of those antigens that's that's on the bottom of the microwell then basically the antibody will bind but you can't see that so you need something else in order to see that and the way you see that is through the use of indicator red cells that are coated with anti-igg so that blue antibody there is an anti-ig uh anti-human globulin basically it binds onto that IGG on the surface and so the red cells the indicator red cells at the top will be shown in a kind of a diffuse carpet across the bottom of the well and that's why it looks like this if you if you look on the right side of this image basically you'll see a four plus positive is a very strong uh I'm sorry is a very diffuse carpet of red cells across the bottom while a negative is a strong button and You' saw the pictures before from tube testing so please remember how this looks it's really easy to mix to mix this up um and to and to call a negative in solid phase actually a positive it's exactly the opposite of how tube testing looks basically across the bottom of the screen you see you see as uh going from four plus to Zer plus and the differences that can occur in between both solid phase and gel testing can be automated with the use of some of the equipment seen here and it's just a sampling of the equipment that's that's available from these companies um but uh there there absolutely can be automation of this testing to make things go smoother and easier theoretically in the transfusion service so let's talk about this me a method comparison I I actually left this out of the of the handout um please forgive me for that I will try and fix that down the line um if uh actually check the very end of the handout once you download it because I'm trying to add this on to the to the very end as an appendix okay so comparing the the methods the most common methods that are used in the United States include tube testing with Liss as a potentiator tube testing with PEG as a potentiator gel system and solid phas system so in terms of best sensitivity well I I think I would say as I said before Peg and gel and solid phase are about the same they're a little a little bit be better than than Liss um one of the things that's interesting is that peg in particular tends to enhance warm Auto antibodies and sometimes you can get some false positives with that gel and solid phase do that as well not quite as much as Peg but but not far behind um Liss potentiation in tubes actually enhances cold Auto antibodies so unfortunately you sometimes see things that you don't really want to see uh the next three columns are are really all about gel and solid phase they they give the most reactions things that can be reviewed later on down the line by a supervisor or other other technologist they are unfortunately the most expensive test to do and they both can be automated so a nice comparison between all these methods for you to for you to hang on to uh a few more things before we before we get into more specifics about pre-transfusion testing the direct antiglobulin test um or sorry the indirect antiglobulin test we've kind of already outlined it basically you we're what we're looking for is is coding of the red cells in vitro in a test tube as the case or in whatever Medium you're using and the yellow antibody there is anti-human globulin that shows you that those antibodies have been coat or sorry those red cells have been coated but not necessarily agutin there's lots of different kinds of anti-human globulin you can use excuse me I'm sorry about that there's lots of different kinds of anti-human globulin you can use including anti-ig anti anti-igg and c3d is called polyspecific um ahg uh and a lot of labs will start with polyspecific and then if there's if that's positive then they'll do the ne one of the next two which is specific anti-ig and anti- c3b or c3d uh fundamentally anti-ig does exactly what you would think it would do it it picks up IGG on the surface of red cells not completely specifically but mostly there can be some overlap anti c3d on the other hand shows that compliment has been fixed on the red cells and and gives you a clue that there may have been another type of of coating such as with IGM which is better at fixing complement than IGG um anytime you do a test that requires a wash phase you have to do what's known as a kum's control also known as check cells basically these kums control are the purple cells here they're coated red cells they're red cells that have IGG Andor complement on their surface they're added to a negative indirect anog globulin test uh to make sure that your your ahg is working work well by definition aum's control or the check cells should be positive because they're coated red cells if anti-human globulin is there and working you can go ahead and you you should go ahead and see a visible utenation um you don't have to do this for a test like gel because that because the plasma doesn't actually go through the gel system with the red cells but certainly you have to do it for for tube testing um all right the direct antiglobulin test on the other hand does the same it's basically the end stage of an IAT it's just taking a sample from someone's peripheral blood and looking to see whether those red cells are were already coated in the body don't forget there's a wash phase you always have to wash to get rid of Unbound globulin uh but other than that the DAT is done in the exact same way that the end of an IAT is done your handout talks about some of the indications and uses for for the dat we don't have a lot we don't have enough time to go into all of those um but there there are definitely some some useful things that the dit dat can help you with especially in terms of transfusion reaction workups uh that you can review those briefly in the handout all right so so some additional tools that are in our arsenal when we're doing pre-transfusion testing include the things that you see on this slide that your enzymes and pre-warming absorptions utions and other treatments of the red cells let's talk about those very briefly and we I get I showed you this illustration before but I love it so much I have to do it again so in the last podcast we talked about the fact that enzymes like fisen and pepan can change antigen expression May either increase antigen expression or decrease antigen expression or increase the availability of those antigens or decrease the availability of those antigens to bind to antibodies here's here's what I mean by that here's just one example so we have a surface of a red cell and let's look at it up close and in this particular case we're going to look at the the an the antigens that carry um sorry the chains that carry the M antigens these are glycophorin and those glycophorin stick fairly far up from the surface of the Red Cell well you add a proteolytic enzyme uh those glycophorins are are are proteins and those glycophorins um those chains can actually be grabbed by protolytic enzymes uh cleaved and you end up with a situation where you have fewer um antigens on the surface or maybe even completely destroying them so that's one way that you directly change an antigen expression on the other hand you can have a situation where uh for example with an with an antigen like RH that's Illustrated in blue those RH antigens tend to be considerably closer to the red cell surface and if they're being masked to some extent by um by those glycophorins that are sticking way up well an antibody can come along and may have an issue getting down to that RH antigen now you and I both know that that's not usually a big deal because RH antigens are expressed well enough and the antibodies bind them really well but if you throw in a protolytic enzyme to this situation goes along does its work and you get loss of some of those uh some of those glycophorins well guess what happens then then the antibody is able to move on and bind even better to those underlying to those underlying antigens here's a schematic of the red cell surface and and this kind of shows you again at the far left is a glycophorin um pardon me far left is a glycophorin that that uh sticks way up from the surface and if you look in the middle those are the RH antigens that are very close to the surface more this is obviously a very busy slide that has a lot more than that but it just kind of illustrates the principle so in terms of how this works this is what I use uh in the last in the last podcast to describe and discuss the different uh the different blood groups and it's the enzyme classification and again you see all these here we talked about them before I'm not going to go over them again pre-warming on the other hand is a way to incubate reagents and samples uh at warm temperatures in order to mask cold antibody activity and that includes both cold Auto antibodies against your own red cells and Alo antibodies against some someone else's red cells people like to do pre-warming because it's it's a way to kind of get rid of some reactions that you don't really want to see but you have to be careful with it because pre-warming actually can weaken significant antibodies and it really should only be used as confirmation don't use it to just make the reactions go away and say oh yay I'm done there's nothing there you really need to take a close look at what you're doing and and figure it out as best you can before you go to pre-warming that that should be used just to kind of confirm your initial Impressions absorption a commonly used phrase that is poorly understood by a lot of beginning students in blood banking basically absorption is a way to remove antibodies from a sample by incubation with antigen positive red cells and you can do this in a couple ways you can do auto absorption and you can do aloe absorption let's start with auto absorption let's just imagine that we have a patient who has a an auto antibody let's call it a warm Auto antibody so it's binding to basically all the red cells as Auto antibodies tend to do and you're getting complete incompatible reactions well unbeknownst to you this person also has an anti-big K underneath that auto antibody but the if the auto antibody is masking all the reactions you may not be able to tell that there's an anti- Big K there so as part of the workup one of the things that you can do is an auto adsorption where you add the patient's own cells which are presumably Big K negative because the patient's made an anti-big k um and those cells basically you just think of it as a sponge they basically absorb or soak up that auto antibody so you're left with a situation after you separate uh your your sample from your red cells you're left with a situation where you have Auto antibody coating the patient's red cells and left behind in the sample is the anti-big K you can then go on and test that that uh that sample and uh which is basically absorbed serum and and show that it actually has an antibody that's very important in terms of what red cells you're going to select for transfusion for this patient again you can do aloe absorption which is looking for antibodies against someone else's Red Cell antigens uh again let's go hypothetical let's imagine we have someone who has an anti- Big K an anti-big C and an anti- big S and when we're doing our testing we we kind of know that there's some stuff there we can identify the anti-big K and the anti-big C for example but we're not sure it seems like there's something else there and we want to figure out what it is well one of the ways that we can do that again is to throw in some red cells that are specific in other words let's in this case throw in Big K positive Big C positive but big S negative red cells again same principle with absorption you would expect those red cells to absorb or soak up the anti- Big K and The anti- Big C and leave behind a sample that has the anti-big S and you can then test that absorbed serum um and determine that that anti-big s is there the next thing we'll talk about is illusion and illusion kind of goes along with absorption in a lot of cases let's stick with this same example um so we've got those red cells that are coated what are we going to do with those well one of the things that we can do is take those coated red cells and do an illusion basically through treatment with either heat or cold including freezing if necessary uh but most commonly in a lot of blood banks chemical treatment with something like glycine will actually cause those red cells to give up their coated sorry give up the antibodies that are coating their surface um and give you a sample that you can use to test that shows anti- Big K and anti-big C so you can test those and figure those out and you let you're left behind with with the red cells that that don't have any coating on them anymore now that doesn't always work some of the things that we do uh can be pretty tough on those red cells so you may have them there or you may end up in a situation where you just kind of flame them and there are no red cells left but you most important in an ution is looking for that uh the sample and the anti the antibodies that may be in it moving on there are some agents that we can use to treat red cells that that kind of change how they react um including dtt or dio3 atol uh direct it's a self hydral reagent that destroys numerous uh Red Cell antigens such as uh Big K in particular k k antigens are destroyed by dtt in addition you can use dtt because it's a self hydral reagent you can use it to deactivate IGM antibodies in serum or plasma samples uh the the the reagent basically dissociates the bonds that make IGM a pentamer and uh and you end up with no activity of the IG the same thing for tumor tumor capto ethanol tme which does this the same thing as dtt in terms of that IGM zzap on the other hand is a combination of of a proteolytic enzyme and dtt so it does exactly what you would expect it it deactivates the uh the antigens that enzymes deactivate strengthens the one that the ones that they strengthen and dtt comes along and and damages the the the Cal antigens for example and whatever else dtt damages chloroquin is used sometimes primarily in reference Labs it's it's used to strip IGG from dat positive red cells um that's most commonly used when someone has a positive dat and you're trying to tell what their actual phenotype is perhaps you're trying to figure out how to transfuse them well you can use chloroquin to get that IGG off of the surface of those coated red cells it also removes some residual ual HLA antigens called the BG antigens from the surface of red cells Okay so we've talked about that for a while um I hope you feel like you have a a solid background in the terminology and technology that we use let's spend a little while now going over the the components of pre-transfusion testing uh it starts with the with the the the donor sample and the testing of the donor sample remember this is the this is the sample from the product that's going to be transfused uh transfusion Services have some action activity to do here but truthfully most of it is done in the blood center on page eight it goes over all the things that are done in the blood center including the different requirements for testing and we're not going to talk anything about that today but the in the transfusion service there's some confirmation of some of that testing that we have to do we have to do testing and you only have to do whoops sorry about that you only have to do the forward group I'm going backwards all right there we go so you only have to do the forward group when you're doing the reconfirmation basically uh just making sure that the way that the the product is labeled is is what's appropriate um RH testing you only have to confirm those that are labeled as D negative you don't have to do a weak D test that we we've talked about before and we'll talk about again in a minute also you don't have to redo all your confirmation of your infectious disease tests that's good news right um so now that we've tested our donor sample and we have products sitting on the shelf that are ready to go let's start working on our patient what are the things we have to do for our patient well it starts with a good collection identify ident identify identify there's it's so important to properly identify the patient who's going to get a transfusion um if if you don't if the if the staff that's doing the photomy don't do this well you end up in in calamitous situations in particular the the one of our worst nightmares in the blood bank is the wbit wibbit or wrong blood in the tube which occurs According to some studies in one in 2,000 samples that scares us because we can do all our testing right and still be in a situ situation where a patient has a problem as a result of the fact that it was garbage in and garbage out um so the steps to collection include the generation of of a request um whether that comes from the computer or it's handwritten identify the patient using a wristband compare that patient information to the information on the request and please make sure that it matches if you're someone who uh who works in terms in doing photomy it's so important the the smallest mistake can cause your sample to be rejected and you you have to redraw a patient uh again for for testing nobody wants to do that nobody wants to tell you to do that so please do it right as often as you can so you draw your tubes and then you do your labeling at the bedside more on that the tube has to be labeled at the patient's side it's not acceptable to label them at the nurses station beforehand or at the nurses station afterwards if you do that it is absolutely a recipe for error and a recipe for disaster I have seen this it's not pretty it's so important especially with in in hospitals today and in outpatient transfusion centers today there's so much going on the best thing that you can do in terms of getting the sample done is to do it at the patient's bedside right away right then after you draw it what do you need to do well you need to put two independent identifiers on that tube um whether full name unique ID number birth date social security number Etc we have to have a way to identify the full botus it's very important that that's the case as well uh okay so all those things are important once the sample gets to the transfusion service then the transfusion service has a job to do basically they have to first compare the information on the request to the information on the tube and I mentioned this before it's got to match it's just that simple it has to match and I'm very serious about this I am incredibly strict about this um and it's not always the most popular thing in the world I'll tell you that right now but I require redraws if there's any discrepancy I very strongly believe that that data shows including this study from 1997 listed on this slide but data shows that it's it's a bad idea to to allow relabeling and that um if if a sample does have even a seemingly insignificant error there's a 40% chance that there's something wrong with that sample uh so a 40 times chance I should say there's something wrong with that sample so I don't mess with it they need to tell us what needed and when it's needed we need to have a way to identify the ordering provider as well as the full bottom us as I said before and what modifications are needed does it need to be washed does it need to be Lucy reduced does it need to be irradiated whatever so all those things are are important the other thing we evaluate is how long that sample is going to be good and that leads us to a discussion of what what we call the the Q3 day rule or the every 3day rule um very commonly misunderstood by folks so let's talk about it for a second let's imagine someone comes into the hospital it's Sunday um they get their sample drawn for pre-transfusion testing they may need a transfusion we're not sure and it's 2:00 in the afternoon on Sunday so that sample gets drawn Sunday immediately becomes day Zero obviously Monday day one Tuesday day two and Wednesday day three so for anything that's done for this patient any compatibility testing any crossmatching any blood typing Etc that's that's done on this patient between now and midnight uh on on Wednesday in our example here that same sample can be used now that's technically only true if the patient has been pregnant or transfused within the last three months if the patient hasn't been then the 3-day expiration doesn't necessarily apply but I will tell you that most transfusion Services just make it three day excuse me just make it three days because it's easier to do and it's harder to determine who's been who's been pregnant who's been transfused so most transfusion services will just make it 3 days Thursday comes along in our example patient needs a transfusion again well they're going to need a new sample and then Thursday becomes Day Zero and the cycle starts all over again I hope that helps to helps you understand here it is in words it's you have to have a new sample every three days if the patient has been transfused or pregnant in the preceding three months um if there has not been a pregnancy or transfusion theoretically you can extend that to whatever time is allowed on the package insert of the reagents and and on the sample tubes that you're using um there is no upper limit and and if you talk to different people in different places you'll see substantially different upper limits more on that just a second you also need to keep the sample for at least seven days post transfusion so what that fundamentally means because you have three days on the front and seven days on the end most transfusion services will keep samples for at least 10 days uh from the time that it arrives so weird situations include preop or outpatient surgery especially nowadays with patients coming into the hospital to get their blood work done and then not having surgery until the next day the day after or a week later or two weeks later or whatever there's a lot of different ways that we can that we can figure out to try and utilize that same sample and your handout talks about some of those and includes making the patient just wear the blood bank wristband for for two weeks or whatever um this doesn't necessarily work all that well but there are a lot of creative methods that we can do again you can only do that if the patient has not been pregnant or transfused if they have been they're going to need a new sample on the day of surgery unless it's been less than 3 days in emergencies um you know there's a lot to say about emergencies but you have to define a system in terms of how you're going to do the samples how you're going to do the identification in particular temporary IDs and how you switch back to regular IDs that's best left to individual Hospitals now the specimen itself can be either a red top or a lavender top um honestly either one works however gel and solid phase actually prefer plasma and that's because in a serum s sample or a red top sample the the the uh plasma may not clot completely so this you may not get a situation where that serum has gone all the way through um and you have you can have debris interference on the other hand though when you use plasma samples you have to remember that anticoagulation because of the Eda actually inhibits some C some complement dependent antibodies and you can miss some of those though that doesn't happen all that often it's a possibility uh also if the specimen is hemal lied or lipemic they're not good uh and we try to avoid using them as much as possible okay so we've got our patient sample it's in the blood bank we've got our we've already done our our donor our donor sample and our donor testing so we're ready to go how what are we going to do we're going to test our patient sample we're going to do testing including both forward and reverse or serum and cell grouping we're going to do the Rh test which is generally done with uh an immediate spin monoclonal polyclonal anti-d uh you you really should it's hugely important because this is difficult for for oldtime blood Bankers to understand you really in modern times should avoid doing a weak D testing week D test I should say on a recipient the reason for that is that most things that used to be called weak D with our current testing are going to be D positive and the few that are actually partial D um are deliberately going to be called D negative uh using the test the the sorry the anti-d that's available today in particular the D6 uh partial D variant which is the most common at least among Caucasians is definitely called D negative by the most common uh anti-d used today and that's exactly what you want you want those people to be considered D- negative so that they don't get exposed to any D any D antigens or any parts of the D antigen against which they can react so basically rhd testing in a patient is deliberately insensitive uh we want partial DS to be D negative you don't want to go on and do a weak D test because you can end up calling one of those partial D people d positive giving them dep positive red cells and causing an issue with them forming an antibody on the other hand it's deliberately sensitive in donors because we want any donor that has either weak D or partial D to be called D positive uh because they theoretically at least have some parts of the D antigen that can cause a theoretical response in a recipient so I hope that's clear and I hope you understand that we also do antibody detection or an antibody screen on our patient sample um important to know that an antibody screen by definition only has to be read at ahg a lot of people will read it at immediate spin in 37 but it doesn't have to be in fact if you're doing gel and solid phase that's or solid phase that's all you're reading at is is the IAT or ahg phase I mentioned before that FDA requires certain antigens to be present on screening cells and you see them listed here they're actually pretty close to alphabetical so they're pretty easy to remember and honestly they're they're ones that you would expect with the exception of a couple of insign usually insignificant ones thrown in there like m and n and P1 and in fact the ones on the second row there Lou a leou b MN and P1 are usually insignificant but they're they're a required part um if the screen is positive you have to identify the antibody you have to determine whether it's a significant antibody or not and that's going to be covered in the next podcast so we won't talk about that anymore if there is a significant antibody then you need to as best you can provide antigen negative blood so who decides what significant well technically each facility makes that decision and decides whether what is significant and what's not significant but obviously there's a ton of published data to tell you what's significant and what's not significant but each facility has to make a decision on what needs to be worked up and and red and sorry antigen negative red cell products provided and what in what cases that doesn't matter okay scooting right along let's talk about the previous records check it's the last thing we do before we do testing of both the donor and patient to testing and evaluation of both the donor and patient together the previous records check is required by a AABB standards um you have to look at the and Rh testing for your donor specifically in the last 12 months but most people will go beyond that as usually in the computer system you also look for typing problems significant antibodies in the past hugely important to look at that and history of of transfusion reactions and special requirements and you have to document any resolution that you do of discrepancy results for example you see now the patient is B positive and before the patient was B negative you have to try and figure out what what the deal was with that um the significant antibody check is really important because onethird of clinically significant Alo antibodies will disappear after one year and nearly a half of them will disappear after 10 years so if you see an antibody a significant antibody in the patient's history regardless how long ago it's regardless of how long ago it's been you honor that and you give the managent negative blood um you also look for as I said difficult testing and all those other things but most important in this slide to look at the history of significant antibodies all right uh moving along so now we're we've done our donor evaluation we've done our patient evaluation now we're going to try and pull those two together and see and evaluate what goes together with these donors and patients and we'll start by what components to select well you select components in in terms of what the provider is asked for obviously by the results of the serologic testing that you've done and by the results of the record check and basically you use all that to provide the safest possible product based on the available is information one thing that's really important to remember is that special modifications are the things that often you'll see historically but you may not see on the current order because it's it's unfortunately uh difficult for all clinicians to remember all the things that are done radiation in particular and and my personal philosophy on this and this is just My Philosophy is that someone has an radiation order it's it irradiation as I hope you know is to prevent transfusion Associated graph versus host disease if they have an order to to irradiate a product I will generally honor that even if they don't ask for it until such time as they tell me to stop honoring it um tvhd is a horrible thing to diagnoses diagnose and I would rather do the irradiation um even if it's not specified on the order each individual facility can handle that whatever way they want to but that's how I handle it okay so once we have all this well how do we decide what to give and well let's start by looking at what type to give here are the general rules if you're doing whole blood you got to go identical there's no way around it there's too much plasma in there and obviously too many red cells in there to do anything other than AO identical if you're just doing red cells on the other hand what you again what we're trying to do in this situation is protect those transfused red cells so the transfused red cells need need to be abio compatible with the recipient plasma uh in other words a person who is uh sorry a person who is blood group O and has anti-a and anti-b a recipient that is should only receive group O red cells to protect those transfused cells the same thing is true with granulites because they granulites are always heavily contaminated with red cells AB compatible with recipient Plasma ffp on the other hand you have to think the other way around we're not transfusing red cells with ffp so we actually want to protect the recipient red cells so you need to have those behavio compatible with the recipient red cells is best you can platelets on the other hand you will read people say things like it doesn't matter with platelets and some people treat them that way I will tell you that the prance of data that I see out there right now suggests that identical is best with playlets uh not only for reasons of a good response to the platelets but also for potential reasons of hemolysis especially um in situations where group O platelets are going to non-group O recipients that's a really dangerous thing and it's not always dangerous and we get away with it quite often but if someone a platelet donor happens to have a very high tighter of usually anti-a and you give that that group O platelet to an to an a group a recipient you can actually see kind of a reverse hemolysis the younger and the smaller the patient is the more of a risk that is I really try to avoid it when I possibly can um there's also data out there that suggests that AO incompatible platelet transfusions can cause can have uh patient that get those can have decreased survival and nobody wants that all right finally cryoprecipitate that there there isn't any uh any type risk with cryo um though if you're giving someone large volumes that that that's called into question a little bit but in general all types are acceptable for rhd compatibility for for DEC compatibility basically with red cell products with a premenopausal female you always want to give him DG unless you're in an emergency situation uh that's just a general General rule that everybody should go by I don't think anybody would debate that however if you're in an emergency situation and you have to switch them well then you have to switch them certainly for D negative males and D negative postmenopausal females they may receive D positive in situations of urgency I don't mean that you should just routinely throw out D positive to these patients but if you're in a situation where you a trauma for example or a massive transfusion it's okay to give them D positive unless they've already formed an anti-d we used to say that in that situation 80% of patients would form an anti-d nah not so much your handout talks about a reference of a really good study that shows only a 22% risk in hospitalized patients of D negative patients of forming an anti-d in that situation for platelets there really is a very small risk and we're seeing this more and more and understanding this more and more um apheresis platelets generally have fewer red cells than whole blood derived platelets so the the risk is smaller for apheresis there's a a recent study again referenced in your handout that showed a 3.8% uh incidence of anti-deformation over a 10-year time frame of D negative patients who got dep positive platelets a mix of of aphesis and whole blood derived without getting prophylactic R rhig My Philosophy is that if you've got a childbearing age female who needs uh who's D- negative and needs a d positive platelet transfusion because of inventory issues or whatever you should always consider rhig and generally I will recommend it okay okay um so uh quickly antigen negative units um are are used for significant antibodies um when we've identified a significant antibody and there are a couple different ways that you can find antigen negative units the serologic method and the molecular method uh molecular is getting more and more popular but basically calogic method look looks with licensed anti-era um and finds units that are negative or donors that are negative for particular antigens it's much easier to do in a blood center because of the big large numbers of donors many of which have already been phenotyped um if you're in a transfusion service there's the calculation in the hand out on page 13 that takes you through how to tell whether or not it's going to be hard to find um an antigen negative unit for your particular patient molecular testing just looks for the basically at phenotype genotypes I should say the donor for this for the main um and in fact a wide variety of genetic sites for blood group antigens you still have to confirm those results because it's not licensed testing at this point you still have to confirm those results with anti-era but it makes it easier to uh to do your screens basically okay so the compatibility check uh we need to talk about that's generally known as the Cross Match and what is the Cross Match well basically it's duh a check for compatibility between donor and recipient and it's especially designed to check for compatibility between donor and recipient when we say Cross Match we really mean major cross match for the most part it's it's when you test the recipient serum versus the donor red cells again we're trying to protect those transfused red cells a minor Cross Match on the other hand is the other way around the donor serum versus the recipient red cells um the other benefit aside from that you can get from doing a crossmatch is you Al can also detect antibodies versus low incidence antigens that may not have been represented on the antibody screen you have to do a crossmatch if there's more than two Ms of red cells in any product which means you got to crossmatch whole blood you a crossmatch red cells and granulites you generally don't have to crossmatch ffp or fp24 platelets or cryoprecipitate um there are three types of major Cross Match two of which are serologic and one of which is electronic the first two are serologic and let's talk about the first one which is the anti-human globulin crossmatch that's also known as a full Cross Match basically it's done uh it's done very commonly in the United States it's required to be done for those who have significant Alo antibodies uh most commonly people are using either list list potentiated tube cross matches or gel cross matches Peg and albumin are are somewhat less used and solid phase is used even less um basically the anti-human globulin detects red cells that are coded with antibody you have to read those reactions at the uh at the ahg phase though you depending on the the platform you're using you go through basically the same steps that you did in the antibody screen is just that you're testing your um recipients serum versus your donor red cells again looking for looking for incompatibility immediate spin crossmatch on the other hand is only used if no unexpected antibodies are present so if you if the patient has no history of antibodies they don't have any now you don't actually have to carry your reactions all the way through to anti-human globul and you can just do that beginning step the an sorry the immediate spin phase and all that's doing is checking for compatibility it's possible that you could miss uh a low frequency IGG antibody uh or sorry an IGG antibody that doesn't react at immediate spin um that's against a low frequency antigen for example but the the risk of that is extremely low and immediate spin Cross Match is generally a very safe thing to do it's faster obviously than the than the full Cross Match and and decreases your use of reagent and potentially reduces your workload the electronic or computer crossmatch on the other hand is only used well basically it's used in the same scenarios that immediate spin is that when the patient has a negative antibody screen but also the additional caveat it occurs it's can be used when the patients have been been and Rh typed on at least two occasions in other words you can do that several ways and your handout talks about some options for this but you have the current sample obviously your current testing and you can either have previous testing that that's present in your validated computer system or you can repeat the repeat the testing on that current sample or some places will go to actually when when it's the the first time you're seeing a patient forcing uh a second sample to be drawn from the patient to again verify so once all that happens then the computer basically compares the results of the and Rh from the donor and the and Rh from the potential recipient Compares them makes sure that they're that there is compatibility there and you can issue the products that way here's just a flowchart that talks about how to do that since we're short on time I'm going to skip that uh electronic crossmatch is obviously potentially faster way less sample required and less agent required uh for the most part and and has the potential to reduce workload uh again for obvious reasons so what what can happen when you suddenly have something pop up during a cross match and I want to talk about this for just a second if you have someone who has a negative antibody screen and all of a sudden they pop up with a positive crossmatch there's some things that you should definitely think about the the immediate if the crossmatch is positive at immediate spin you need to think about incompatible donor red cells basically what that's telling you is that there's an issue there that I mean this is what immediate spin Cross Match is designed to do if you have if you have an issue with how you types the donor with how the how the recipient was typed if there's some incompatibility it should come up positive um on this test so investigate that uh cold antibodies like anti- A1 can show up at immediate spin or anti-m for example can also do the same thing if it's positive at the ahg phase or the kums phase as it's also called uh the most common reason for that an antibody against a lowf frequency antigen you can also have issues with how with the testing that you've done but that's the main thing that you should think about your handout goes into a little bit more detail on positive Cross Match after positive screen but again for interest of time let's finish this off by talking about the label and final records check um basically once everything is ready to go and that unit is ready to go out the door you tag or label that unit uh with generally a uh a tag that looks somewhat like what you see in the picture there that tag includes the recipient's two identifiers that we talked about before has to have the donor unit number and the results of compatibility testing if such testing has been done and it also has obviously the regular stuff that's on the that's on the label uh that you would normally see and this is an isbt label that you see right here from Johns Hopkins yeah all that needs to be on there as well but the what we're talking about is the the the compatibility testing label and the pre-transfusion testing label that shows those results and must be on there as well the C iCal check U again a big busy slide but basically both at the time of the the time the product is issued from the from the transfusion service and at the bedside there are some things that have to be checked according to ABB standards and you see them there and it's just basically the things that we checked all along in terms of identification so let's let's not take any more time to do that lastly let's talk a little bit about the order types and the nomenclature and here are the four main order types excuse me for pre-transfusion testing the whole hold clot is very uncommonly used the it's it's basically a clotted sample is held in the transfusion service but it's not tested at all it's just to have it there just in case something should happen so again not commonly used type and hold same kind of deal the only difference is that with type and hold you actually do type and Rh uh that that particular recipient but you don't again you don't do anything else again some places use this uh I haven't found it all that useful but but some people do it um the type in screen is a better test from from my perspective with a type in screen you do a records check looking for looking for what the how the patient typed previously uh you don't use that to for your current typing obviously you have to it's just for comparison once you do your and Rh type typing and you do antibody detection or an antibody screen if that antibody screen is positive then you need to go and identify the antibody regardless of in my opinion regardless of whether actually it's not just my opinion regardless of whether they've ordered a type in Cross or not but if the antibody screen is positive go ahead and identify the antibody and see if it is clinically significant type in crossmatch on the other hand includes everything that we talked about before plus a major crossmatch either serologic or electronic depending on depending on the patient's history um and then once you do that then Red Cell units that are designated reversibly for that patient's use are set aside um if they're not used they can always be re-released into the general inventory that confuses some people sometimes if the antibody screen is negative okay so convert let's talk for just a second often times we have discussions with clinicians about your for example you're ordering every single case to be a crossmatch and so we're tying up a whole bunch of blood yeah reversibly but it's temporarily unavailable for your patients none of whom you're transfusing if you find yourself in that situation you can advocate for the use of the type in screen rather than type in Cross and clinicians always want to know well how fast can I get the blood how how does this work well if the antibody screen is negative then it's really easy to convert a type in screen to a type in Cross all you need to do is the check and that can be done with an immediate spin Cross Match which takes very little time or an electronic or computer crossmatch which also takes very little time you can also assure them that if the antibody screen is positive on your type in screen then you automatically will convert that to a type in Cross Match after you identify the antibod so you you will determine what the antibody is get antigen negative units ready obviously that will usually entail some communication between yourself and the clinician um and and it's it's important to have that communication again you can reassure them that we know how to handle this process there's some variations in babies that are less than four months old basically with pre-transfusion testing and cross matches you can uh you can check the baby's and Rh and the check the mom's antibodies because they're the same as baby and after that you don't have to do cross matches or serum grouping as long as as long as you're staying within certain specific parameters um finally let's talk about the m boss the maximum surgical blood ordering schedule which is basically a list of procedures that uh that outlines what the appropriate blood order is for that particular surgical procedure the order can be none in other words you don't need a sample at all type in screen or a type in crossmatch for X number of units most importantly it needs to be Hospital specific and it needs to be approved and discussed widely uh with with the clinical staff it can be a really useful tool for especially in situations where people are ordering types and crosses for example when they should be ordering types and screens but unfortunately it's not nearly as widely used as it used to be it's a little bit of a hassle uh in fact it's in many cases it's a lot of a hassle this is a an example of one part of the mboss from the University of Michigan that they published online thank you to them specifically for cardiovascular surgery where it talks about for example at the top top left aneurysm thoracic reection type and cross for four units you see on the right you see some sample some uh procedures that would be type in screens um and in other parts of the Miz boss you would see things that you wouldn't need a sample whatsoever all right woo um so we have covered a whole heck of a lot of stuff I really want to thank you for hanging out um again the antibody ID podcasts are coming soon uh I I honestly I just so appreciate you guys being here and hanging out and listening to this please send me feedback in whatever form you desire whether that's Facebook or Twitter or contacting me directly through the website um I I uh am so glad that you were here I'm so glad to have spent this time with you I hope you enjoyed it I hope you I hope it's been useful for you have a great [Music] [Music] day

Channel: Blood Bank Guy (D. Joe Chaffin MD)

Views: 166,429

Keywords: immunohematology, Chaffin, Pretransfusion, blood, ABO, Rh, blood groups, Blood Bank Guy

Id: ORhL_ictvFY

Length: 69min 59sec (4199 seconds)

Published: Sat Oct 20 2012