In simple terms, quality control in a blood transfusion lab refers to any or all the activities done by blood transfusion staff to ensure test results are accurate and reliable.
Quality control is the responsibility of anyone who works in the Blood transfusion lab.
For instance, it’s the responsibility of any staff member to close an open fridge that was opened by mistake. You do not continue to leave it open because you didn’t open it.
By closing it, you are protecting the reagents or blood products inside the fridge from exposure to the wrong temperature.
So, you are being quality-conscious.
However, there is more structured quality control work with designated responsibilities. These tasks must be done by identified medical scientists with the skills and training to do so.
And that is the main focus of this article.
Before we go into detail, it is better to have an idea of what a blood transfusion lab looks like.
Here we go!
Table of Contents
Overview of a Blood Transfusion Lab
A blood transfusion lab is simply where blood(Red cells, Platelets, etc.) and other products like plasma are tested for safety before a patient can be transfused with them.
This is achieved through numerous tests done in the blood transfusion lab.
Those tests are:
Blood grouping (for donors and recipients)
Blood crossmatching (Donor cells against recipient plasma)
Antibody screening
Infectious disease screening(HIV, Hepatitis B&C, Syphilis etc.)
Direct Coombs Test(Direct Antiglobulin Test)
Indirect Coombs Test(Indirect Antiglobulin Test)
These tests listed above are fundamentally common in the majority of blood transfusion laboratories.
However, what may differ between labs is the methods or technology used to carry out those tests. The more advanced and complex a lab is, the better the method used.
There are some other tests done in some advanced Blood transfusion laboratories.
They are
Rhesus variant typing
Human Leukocyte Antigen(HLA) typing
Red blood cell phenotyping
And more….
Our focus will be on the more common tests that the majority of blood transfusion labs can perform.
But there is a catch….
Some countries differ in blood transfusion activities, which determine the kind of tests done in hospital blood transfusion laboratories across the given country.
In the United Kingdom, NHS Blood and Transplant (NHSBT) handles blood donations and provides blood to hospital labs.
Their counterpart in Kenya is called Kenya Blood Transfusion and Transplant Service(KTTA).
This means that some tests, like infection screening or more advanced tests like Red cell expanded phenotyping, are not done at the hospital blood transfusion laboratories but at the National Blood service providers like the NHSBT and KTTA mentioned above.
The implication is that Quality Control activities in a Blood Transfusion lab are restricted to the kind or number of tests done in that particular lab.
You don’t control what you don’t do.
So, basically, we are going to make assumptions to enable us to have a focus or a direction.
We will assume that Blood Transfusion Labs run these tests below.
1 Blood grouping (for donors and recipients)
2 Antibody screening
3 Blood crossmatching (Donor cells against recipient plasma)
4 Direct Coombs Test(Direct Antiglobulin Test)
Now, what will quality control look like in this lab?
We will divide the quality control here into components.
Components of Quality Control in Blood Transfusion Laboratories
There are two components of quality control.
Internal quality control (IQC)
External quality control(EQC)
Internal Quality Control (IQC) in Blood Transfusion Laboratory
These are regular checks and tests to identify and correct any issues in real-time.
Doing this monitors the quality of a process and results within the lab.
To emphasize, internal quality control means that external bodies do not check the activities (except during external audits to check if they are done as stipulated).
With reference to the test listed earlier, this is how the IQC will be done.
Blood grouping (for donors and recipients)
The blood grouping reagents are usually monoclonal antibodies (Anti-A, Anti-B, Anti-AB, &Anti-D Reagent).
There are also known or typed red cells (Group A, B, AB, and O) reagents.
This is for manual blood grouping on a tile or in a tube.
There are also blood grouping reagents in the form of Cards, where the antibodies are already in microtubes in the cards. This is not regarded as a manual grouping method.
The first step for IQC here is that when the reagents mentioned above are bought, they are tested in a process called batch acceptance, and they have to pass before they are used for patient tests.
Batch acceptance is done once unless the initial test fails.
The next step is to run the control reagents(Known blood type against known antibodies) first every morning before running the blood grouping test on patient samples. This is usually for the manual method.
The card method of blood grouping usually employs an inbuilt control in the form of reverse grouping. This reverse grouping MUST confirm the main (forward) grouping.
Any disparity must be investigated.
However, the frequency(daily, weekly, etc.) of quality control for manual blood grouping can be determined by a given lab.
These IQC runs must be documented, dated, and signed. The document must also be archived or filed properly for easy retrieval when needed.
Signs of poor or no IQC for Blood grouping test
- When you buy the reagents, you start using them for patient tests without batch acceptance.
- When there are no daily or weekly controls done before running patient samples
- When there is no documentary evidence, even if the controls are run.
Let’s look at the next test.
Antibody screening
During antibody screening, the plasma of the patient or recipient is checked for the presence of any antibody of clinical significance(like antibody to Rhesus antigen)
If the patient has a specific antibody in his plasma, he must be transfused red cells that lack the corresponding antigen.
For instance, if a patient has an Anti-K antibody in his plasma, he must be given Red cells with no K antigen. The reason is that the K antibody will react with the K antigen on the transfused red cells and destroy them.
Quality control in antibody screening involves using a low-titre positive cell, especially heterozygous expression, in a card screening test.
Positive heterozygous Duffy cells (Fya+fyb) can be used depending on the company that produces the screening card.
In the practical sense, there are commercially prepared red cells with known antigens. These red cells are usually in a panel of 3, 6, 11 and more.
Panel 3 means 3 different red cell vials (1, 2 and 3) each one containing known antigens.
Panel 6 means 6 different red cell vials(1,2,3….6) each one containing known antigens
The same applies to panel 11.
Panel 11 will give you access to more red cell antigens than panel 3.
Nevertheless, whichever panel you are using in your lab to screen for antibodies must incorporate IQC, which must be positive or Negative for the test to be valid.
Remember, documentation is the only proof that IQC is done!
Next…….
Blood crossmatching (Donor cells against recipient plasma)
When a patient needs to be transfused with Red cells, no one knows the patient’s antibodies in his blood(the plasma part, not on the Red cell surface).
No one also knows the antigens on the surface of the donor’s red cells.
Nevertheless, there are some that we know. Someone with blood group A has antigen A on the surface of his red cells and antibody B in his plasma.
Someone with blood group B has antigen B on the surface of his red cell but antibody A in his plasma.
If you transfuse Blood group B to a patient with blood group A, the B antibodies in his plasma will attack and destroy the B red cells transfused.
This is what we call INCOMPATIBILITY.
So, crossmatching aims to determine compatibility(no reaction) or incompatibility(reaction).
If the patient’s plasma reacts with the donor red cells in the tube, the donor cells must not be transfused to the patient, and the cause of the reaction must be investigated.
During crossmatching, especially when using the card method, an IQC is incorporated. This IQC must pass before the crossmatching result is said to be valid.
The IQC in use here involves reacting a cell that has a low titre of fya(heterozygous expression) antigen against the fya antibody.
Next is ……..
Direct Coombs Test(Direct Antiglobulin Test)
This test can be done on either patient or donor red cells.
DCT basically checks for the presence of an antibody, complement, or both attached to the surface of red cells.
Normally, red cells should not have complement or antibodies on their surface.
Depending on the test volume in a given lab, IQC for DCT can be done daily or weekly. And it has to pass.
The DCT test card usually contains the following immunoglobulin(IgG, IgA, IgM) and C3d and C3c complements.
External Quality Control(EQC)
EQC is an extra layer of quality checks(support over IQC). It is a method of ensuring the accuracy and reliability of laboratory testing by comparing a laboratory’s results with those from external sources.
This can involve comparing results with a peer group of laboratories or a reference laboratory.
Things to know about EQC
1 EQC is usually a National or international program (e.g., NEQAS in the UK)
2 A lab must be registered to participate in an EQC
3 EQC is usually mandatory or a condition for laboratory accreditation
4 EQC samples are sent from the providers of the service
5 The same lab personnel that run daily tests will also run the EQC.
6 EQCs are not supposed to have special treatment.
7 EQC means the same as EQA(External Quality Assessment)
8 EQC or EQA can also be referred to as Proficiency testing.
9 Your lab can be registered to many different EQC programs.
10 The frequency of EQC samples in a year is defined.
For instance, an EQC provider can send blood grouping samples to the registered labs 12 times a year and might send samples for DCT 3 times a year.
When EQC samples are sent to the registered labs, they usually have deadlines to submit their results through a dedicated website.
A new employee’s medical scientist training is incomplete until he or she has run an EQC sample.
And that brings us to the end of EQC.
The other part of Quality Control we must mention is Storage.
Temperature storage condition.
All the reagents in the blood transfusion lab have specified storage conditions and MUST be followed.
Some reagents are best stored at room temperature and must never be refrigerated or frozen.
Some are best kept between 2-8 degrees and must be kept so.
Some, like fresh frozen plasma, must be frozen until it is needed.
The temperature monitoring system for both the room temperature and fridges must be robust and have an audible alarm system in case of deviations.
Platelets are stored in an agitator at a temperature of about 22 degrees.
These are all part of quality control in blood transfusion
