Sample collection for clinical lab:INTRO>>Preanalysis-part 2

Sample collection for clinical lab:INTRO>>Preanalysis-part two

General Guideline for sample collection


Hi, welcome again in sample collection section …. we are still talking about the specimen collection introduction in which we previously talked about the specimen type classification and the pre-analysis part one in which we talk about the data collected from the patient and the data collected regarding the test.

Now, we will talk about general important guidelines for sample collection.

There is one thing about collecting data that you should ask your patient if this is the first time do tests in your lab or not? and this is to follow the result of the previous tests and can write down the previous tests in the new reports as a history for the patient’s doctor but id you use a computer program for managing your lab system then you don’t need to ask this question because the program tells you this and this is good to make the patient feel that he important to you and you do care about him.

So, What will you do after collecting data???

After you meet your patient and fill the board form in which you collect the patient data, you will start to focus on the tests requested for the patient by his doctor and then:-

  • If the specimen will be collected by you, then should prepare the sampling room if the samples will collected in sampling room where you will prepare the suitable containers and tubes and syringes if it is a blood sample or other tools you need.
  • If the specimen will be collected by the patient, then you should give him/her the container or other needed tools and tell him/her the instructions of how collect clean sample according to the sample types.

Is it that simple process??? Yes, but there are some important notes and guideline to reduce the errors that may produce incorrect results and leading to wrong diagnosis and may be death…. So, what these guidelines?.

1) Guidelines regarding physiological factors of the patient:

It may be weird but it is very important …. These physiological factors can be called diurnal variations which is exercise, diet, stress and posture.

We already have talked about the diet variations and how diet could affect test results in the pre-analysis part one but now we will talk about exercise, stress and posture…. but we will talk about posture in the phlebotomy topic in blood sample collection.

a) Exercise:-

Exercises increase the metabolic activities and hence affect the substance that is affected by the metabolic process such as free fatty acids (FFA) and creatine phosphokinse (CK)

One can tell me that the effect of exercises is transient that is varnished after finishing the exercise ….. actually there is transient effects and long-term effects.

Examples for the transient effects:- decrement of FFA followed by its increment, elevating CK, aspartate aminotransferase (AST) and lactate dehydrogenase (LDH)

Example for long-term effects:- increase in CK, AST, ALT and LDH and decrement of serum gonadotropin and sex steroids in long-distance athletes.

b) Stress:-

 Of course physical and mental stress can affect hormones because hormonal system is affected by the Nerve signals…. for example when you get angry, cortisol levels elevated …. and of course hormone level affect some chemical processes in our body.

So, if your patient is angry from anything, tell him that he should come down because this will affect the test results and try to be friendly with him/her and make him/her laugh if you could ….. also if the patient is tired from the way he spend to get to your lab, tell him that he should rest for 15 or 30 min.

Generally you should tell your patient that he/she shouldn’t change their diet for 24 hr and also stop exercising for 24 hr and if he/she refuse you can tell him that this may affect the test results and you will do the test on his/her responsibility and write down these notes in your report for the patient’s doctor to take it into consideration.

2) Guidelines regarding specimen collection:-

a) Test order:

There are many errors that can occur in writing the test order or some labs called job order in which you write down the tests requested by the patient’s doctor.

This can be differ according to the lab level; is it small lab or lab with many branches …..

In small labs, test orders may be just written in copybook or paper record (i.e. doesn’t using computerized system) and this means high chance for making errors …… and what the receptionist do is first write the required tests in a copybook then write the tests on another form to give it to the phlebotomist or the laboratorian and thus there are 2 chances for making errors; one when he write down to the copybook and the second when write the tests in the form sent to the laboratorian

Another error chance is the error due to bad hand writing where bad hand writing can be read something other than the required tests ….. but what if the patient’s doctor write the tests for the patient with bad writing??? the answer is, if you can’t read it or you can read it but not 100% sure, you must call the patients doctor and ask him for the tests he wrote.

but to avoid this you should revise what you write in the copybook and the paper requisition form more than once to make sure that you write the required tests or you can make a printed form in which all the tests available at your lab is printed with checkbox beside each test and you just check the required tests

Also even if your lab is small lab, you can use computerized systems to avoid these errors and make patient’s lab history which will be more easily retrievable.

In large scale labs (labs with many branches), Computerized systems are used for sure, and this make these errors rare to occur so, it is more efficient if each lab section has a computer and the test order entered by the receptionist on the system is shown automatically to all lab sections through an internal network.

In my opinion, the most perfect system to avoid errors that can occur in test ordering is the computerized lab information systems (LISs) in which the physician enter the tests required by himself along with some fundamental patient data through an online network between the lab and the doctors or through the lab website and this avoid the errors that can occur when entering the tests by the receptionist or that can occur due to bad hand writing ….

So, what if the doctor make a mistake during entering the tests?? it may be possible but if this occurs, it will not due to lab mistake and no one can blame the lab staff.

But if there is no Possibility that physician can enter tests through computerized lab info systems due to low resources …. just do your best ….. for example, you can make printed test requisition with your lab name and logo or may be with the physician name it self  and this printed requisition contains all the available tests in your lab and also just the patient full name and age and then you will complete the patient data on your lab ….. Thus, the physician just record the patient name and age and check (√) on the required tests and thus you also minimized the errors.

Finally, DON’T FORGET to write the identification number for each test order and patient which is the unique identification number for each patient and each test order.

b) Specimen identification:

Of Course, you should be very careful during specimen identification …… you should setup a system for sample identification to avoid errors for making unknown blood samples or samples that can be distinguished from each others due to the same full name.

You can use a primitive and simple system in which you can just bring the required specimen container or tubes and write down the patient name, patient lab ID, Date and if you can the required tests ….. and when you do this try to use a marker or a pen whose ink can’t be removed by hand or water.

OR you can use more advanced system which is a barcode system on which the patient name and lab ID are recorded and other details (according the program version) are seen on the computer screen when the barcode is read …. all what you need is to print barcode with the test order and deliver it to the phlebotomist and he will put the barcodes on the tubes or the container and then start sample collection… but don’t prepare tubes for 2 different patients at the same time because you can collect sample in the tubes of the incorrect patient name.

c) Time of collection:-

this is simple and it is rare to make mistakes in this regard but it may occur if there is a large load on your lab and you receive samples that should be done immediately ….. in this case the chemists or phlebotomists may be lake special knowledge about  the time of that test can make a delay on specimen collection which leads to incorrect results.

The most solution for this is to buy a laboratory information systems (LIS) that contain the time of each test and the instruction that the patient should do if the sample will be collected by the patient himself and thus make any one, even the receptionist to know the exact  time when he enter the test order on the computer or when he print the test order ….

This also will help the phlebotomist when their is large load in your lab >> how??? this will make the receptionist to inform the patient with the instruction need and arrange the samples that must be collected according to the highest priority(the timed sample take the highest priority) without the need to ask the phlebotomist.

But what if their is no specific time to collect the sample and the patient’s doctor request is to do the test now??? in this case, the receptionist will consider this and your computer program should have the option to add this special timing.


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