Bloom's Taxonomy - You Should Know This!

I cannot stress how much all of us involved in education, either on the teaching or on the learning side of things, should have some knowledge of Bloom's Taxonomy of Learning.

One of the biggest problems is that learners do not understand what level of knowledge is required of them and tutors don't know what level of knowledge they are required to teach to.

All too often, in the past, it has been left up to the individual tutor to "know" what level of understanding is required. But over time we have all drifted in our various directions so we are all teaching and learning to different levels.

Sounds alarming? It should do!

This is one of the reasons why the development of standards seems to be pre-occupying those at the top of the NHS and Blood Transfusion. If you have a well written standard then everybody should know what is expected of them - they would do if thy understood the learning levels as outlined by Bloom.

So take a bit of time to have a look at the diagram and understand what the different levels required of the learner as far as understanding what they are doing.

If we know what the target is then we can have a good idea of how we are progressing towards our goal (and if we are not then we have a better idea of what we need to do to get back on track again).

Email Posting Test

This is just me checking if I can email content from my computer at home to my Transfusion Blog

 

 

Andy Test - BCSH Guideline on Massive Transfusion

Andy Test - BCSH Guideline on Massive Transfu… » Quiz Maker

Know Your Abs from Your Ags

If you are just starting out in Transfusion Science you can really go a long way very quickly (and get a lot of marks in exams) by sorting out your antibodies from your antigens - I see such a lot of exam ansers where I can tell that the person knows the stuff but they get themselves in all sorts of knots with their nomenclature.

I've produced a list of what we are looking at:

1. Phenotyping - here we are using known antibodies (in the antiserum) to look for the presence / absence of antigens on the patient's cells - antibody known / antigen unknown
2. Reverse group (ABO) - we are using the known antigens on the reagent cells (A1rr, Brr and OR1r) to look for the presence / absence of the naturally-occurring anti-A and / or anti-B in the patient's plasma - antibody unknown / antigen known
3. Antibody Screen - we are using reagent cells (two or three screening cells) which exhibit the most common antigens to try and detect any atypical red cell antibodies in the patient's plasma - antibody unknown (if present) / antigen known
4. Antibody Identification - once we have detected atypical antibodies we test them with a panel of cells where we know their antigen makeup (whether or not each cell has each antigen or not) to identify the antibody / antibodies we have detected - antibody unknown / antigen known
5. Serological Crossmatch - we have done the work and avoided antigens to which the patient may adversely react. We now test the cells (antigens) we want to put into the patient as a transfusion with the patient's plasma (antibody) as a last test to see if there are any antibodies in the patient plasma that may react with any antigens on the cells in the blood we will transfuse - antibody unknown / antigen unknown

How to Answer a Simple ABO Question

When I'm marking exams I see so many easy marks thrown away by students because of sloppy answering techniques so I thought I'd give an example of how I would answer a question - I'm not saying this is how you should do it but just how I do it.

This sort of question usually comes with questions like

1. What is the blood group of this patient?
2. Comment on the results
3. What additional tests would you perform?
4. What blood would you provide for this patient?

Before we begin - are all the controls present which should be and have they worked? All the controls are present and they have worked as expected so we have a valid test result - we can continue.

What is the blood group of this patient?

There is something wrong with these results so is there anything we can actually say? yes. We can say that this patient is RhD positive. We can't say that they are a group O because the reverse group does not agree with the forward group. We could hedge our bets and say that this patient "could be a group O" or "phenotypes as a group O in the forward / cell grouping" because this alerts the examiner that there is some doubt in your head about this group (which is a good thing).

Comment on the results

Here we are looking to see if you know what is wrong with the results and if you can give any sort of reasoned explanation as to why the results are the way they are.

In this case we can say that the patient's forward group tells us that they are a group O but if this was the case then we would expect to see anti-A and anti-B present in the patient plasma (reverse group) - we are not seeing this. This way you've alerted the examiner that you know what is wrong with these results and why they appear wrong to you - you have demonstrated your knowledge rather than relying on the examiners' telepathic powers - do not assume that an examiner can read your mind!

Now that you have pointed out what is wrong with the results are there any explanations as to why they are wrong? In this case there could be the following explanations:

1. This patient could be a group O neonate who is yet to develop anti-A and anti-B in their reverse group
2. This patient could be a very elderly person whose levels of plasma anti-A and anti-B have fallen to such an extent that they are now undetectable
3. The patient could have agammaglobulinaemia or severely immunosuppressed and so be unable to make immunoglobulins (including anti-A and anti-B)
4. The tester could have forgotten to put the patient plasma into the test

What additional tests would you perform?

This answer is governed by you explanations to the previous part of the question - this way you demostrate your reasoning behin your choice of tests rather than you are throwing the kitchen sink at the test in a hope that something may work!

You could suggest:

1. Repeat the test to see if it was operator error
2. Double the amount of patient plasma you use in the reverse group to see if you can detect very low levels of antibody in the patient
3. Repeat the reverse group at 4C as ABo antibodies are IgM in natute and work better at lower temperature (displaying your knowledge again) - this should pick up low levels of antibodies
4. Look at the patient's notes to see if they are a neonate or very old or suffering from some condition which could affect the test in a way demostrated by the results

Again, each response gives the examiner confidence that you know what you are talking about and that you are doing things for a reason.

What blood would you provide for this patient?

Here comes the difficult one - are you going to put the patient's safety at the top of your list or are you going to play chance with their life? Better to be safe than sorry and link it with your comments. Also, don't forget any other requisites for the blood if you talking about certain patient groups:

the phrase "I would not transfuse this patient until I was confident of their actual group" is always a winner but you could add, "In case of an emergency I would select group..."

Neonate: Group O RhD positive (include CMV-, HTO- / lysin - , irradiated)

Elderly: Group O RhD positive blood

Agammaglobulinaemia / immunosuppressed: Group O RhD positive irradiated blood (+CMV- perhaps)

As you can see I've done my best to explain why I've done what I've done - I have displayed my knowledge of a much wider subject area than just the ABO group to the examiner and not made them have to assume the reason why I've made the choices I have made - you don't get any marks for that! It is like the old comment in maths exams about "show your workings". This way, even if you get the answer wrong, the examiner can award you marks for the "way you were thinking" if it was in the right direction - just an answer which is wrong will give you no marks!

This explanation is a lot more long-winded than the actual process!

Try answering some questions for yourself and then looking at you answer and seing if it is obvious:

1. why you have made the decisions you have made
2. that you have demonstrated your knowledge
3. that the examiner is in no doubt why you have done what you've done

An Inability to Communicate

Here's a problem I'm encountering more and more!

Learners know all the facts but are rubbish at communicating their knowledge!

All the time I come across this and it is getting worse (in my opinion) - if I ask a learner loads of questions about haemolytic disease of the newborn (HDN) then there is generally no problem, the learner answers all of the questions correctly. If I then ask the same learner to "tell me about HND" - disaster! They are unable to fit all of their bits of knowledge together and form it into a cohesive discourse on the subject.

Now I am sure this is due to to the way we learn things. In today's hectic world we tend to learn in soundbites - small discrete chunks of knowledge, but we don't take the time to reflect on that new knowledge and "sort it out" in orr minds. The result is that they stay as discrete chunks of knowledge rather tyan coalescing into knowledge about, and so mastery of a subject.
Can we change this sorry state of affairs?

Of course we can - but it's going to take some effort. Learners need more time to digest what they have learned and more opportunities to manipulate that knowledge to learn how to use and apply the knowledge. that means more of us senior members of staff discussing things with those that are learning - exploring a subject rather than just testing the knowledge of facts.

Windy's Advice

Here's some suggestions from me:

1. Talk with your learners - don't be judgemental otherwise they will just clam up - the idea is to get them to discuss their ideas on a subject rather than them trying to say what (thay think) you want to hear.
2. Set some open-ended questions for them to do - don't just comment on their "fact retrieval" but comment on their writing style. One of the best and hardest tasks I set my learners is to select a target audience for their their answers - members of the public, consultant haematologists, patients, nurses and other scientists - these are really difficult (but enjoyable to do) and can utterly transform the answers to the same question.
3. Get learners to discuss topics with their peers - this is great "low-risk" feedback as a group will probably know more about any subject than one expert - this way they can make mistakes without losing kudos in the eyes of the expert. Make sure you are on hand to answer any queries the group may have though.

There you go - that's my two penneth on one of my major hobbyhorses.

The Indirect Antiglobulin Test

Surely everybody in serology knows about the indirect antiglobulin test (IAT) as they probably use some form of it hundreds of times a day. I agree but then everybody also assumes we know what we are talking about and those who don't know get too embarrassed about asking. So let's have a little look at it now.

One of the problems with IgG antibodies is that they can sensitise cells really well but are a bit bit rubbish when it comes to agglutinating them and making that reaction visible to the tester - this wouldn't be so bad if IgG antibodies were not so darned clinically significant with the ability to cause haemolytic transfusion reactions and haemolytic disease of the foetus and newborn.

We need a way of showing that sensitisation reaction - Prof. Robin Coombs (1921-2006) came up with the answer by using anti-human globulin (AHG). AHG are antibodies against antibodies so, rather than sticking to antigens, they stick to antibodies - if those antibodies happen to be stuck to antigens on a cell (sensitisation) then they can cross-link with each other and bring about agglutination. I'd have given him a Nobel Prize for that but what the heck.

Let's have a look at the test then - this should make things a bit clearer.

Take your cell suspension and add the antiserum, incubate it and (if there has been a reaction) you'll get this:

In this picture you can see that there has been a reaction between the antibodies and the red cells (because they have recognised the antigen on the cell surface and stuck to them.

This could be a very strong reaction or a very weak one but they will both look the same - just like a negative result, This is because the antibodies have sensitised the cells (coated them) but are unable to cross-link between the cells and join them up to form agglutination (the clumping together of cells due to antibodies).

We need to add AHG but before we do that there is a very important step - wash the sample.

Why do we need to wash the sample? If the serum is from a patient then there will be LOADS of other immunoglobulins in it protecting the patient from diseases and whatnot - the AHG will stick to thes just as surely as it would stick to those antibodies coating the cell and the AHG, even though it is very concentrated, will be neutralised and you'll get a negative result with or without the cells being sensitised. If the serum sample is actually a specific antiserum you are useing to test the cells then there will be massive amounts of that antibody in there, not all of it will be on the cells and the free antibody will, again, netralise the AHG. Washing the sample (with buffered saline, not water!) removes any unbound material so the only immunoglobulins left in the sample will be those which are bound to the cells (if any).

We can now add te AHG (the cyan antibodies in the picture). these will bind to any antibody in there - as we have washed the sample these antibodies will be bound to the cells.

The AHG can therefore bind to antibodies bound to different cells and cross-link them causing the sensitised cells to agglutinate!

And that is the genius of Coombs!

Of course, as we are all good serologists we need to control the AHG step because who is to say that are result is actually negative or did we forget to add any AHG or not wash the sample so that all of the AHG has been neutralised?

To all of our negative tests we need to add sensitised cells (cells known to be coated with antibody - usually RhD+ cells coated with anti-D because they are cheap and easy to make). When we add these calls, centrifuge the sample and re-read it we should see some agglutination thus proving to ourselves that there was AHG in there in the first place and that there is enough to cause agglutination - it wasn't neutralised! Another way of ensuring that we've put the AHG in is that AHG is often coloured green so it is easy to spot if you've missed a tube.