specimen collection for clinical lab:INTRO>>Preanalysis-part one

Sample collection for clinical lab: THE INTRODUCTION>>Pre-analysis-part one


Sample collection is not just collecting urine sample and withdrawal blood sample but it involves some steps and factors that is very important and if these factors or steps is not performed well may lead to death of the patient …… DON’T PANIC, these steps are easy but you should setup the policies and procedures that make sure that you do these steps well…. let’s know how this stage is very important.

The word pre-analysis means the steps that precede analysis stage (i.e. before performing the test) …. let’s think what you will do before performing a test:-

  1. Collecting Patient data and data regarding the test.
  2. Sample collection and identification.
  3. Sample transportation, if you will make the test in anther lab
  4. Receive the sample if it is transported to your lab
  5. Sample storage, if you will not make the test immediately
  6. Prepare the samples for testing
  7. Transporting the samples to lab sections

If you don’t transport the sample to another lab or receive samples from another labs, you don’t need steps 3 and 4 and if you make the test immediately, step 5 is not needed.

In this topic we will talk about the data collected from your patient and data collected regarding the tests and in the next pre-analysis parts we talk about general guidelines in each step and when we talk about the collection of each sample type we will talk about the specific guidelines for each sample type

1) Collecting patient data and data regarding the test:-

There are some traditional data that must you collect for any tests and others are required in case of some tests…. Let’s see this data:-

I) Data that Must be collected:

a) The patient name:-

Of course, you should write down the patient name but you should write the FULL NAME which consists of the first name, the middle name, and the last name …. this is very important to avoid Non-discrimination of 2 or more samples of the same first and middle names.

b) Telephone and cell phone numbers:

You should write down the patient telephone and cell phone numbers because you may need to reach your patient for emergency or to ask for something.

For example, you withdraw a blood sample from your patient and your patient leave your lab and will return the next day to get the results, but what if the sample is not sufficient and you need more serum or plasma to perform all tests?? or You can lost the sample by accident…. In this case, you should call your patient and explain the situation and tell him that he/she should come again to get another sample ….. IMAGINE that you don’t have the phone number and you can’t call or reach your patient, what will happen??? the patient will come to you to receive the test results and you will tell him what happen or the situation … in this case the patient will get mad and of course you will lose you patient and may be your reputation but if you call him and explain the situation, he/she will feel that you really care and honest with him/her and will come to you again to get another sample and you will not lose him/her.

Or you may ask the patient about that if he take some medications that affect the result of certain test or ask about the dosage of a medication he already take…. especially in case of coagulation factor tests.

c) Patient address:

This is good in 2 cases; the first, if you can’t call him for an emergency conditions you can go to his/her home and the second, your patient request to send the printed results to his home.

d) Patient Age:

This is necessary because the reference value ranges for some tests depends on the age and if the age is faulty recorded then the reference values of some tests will be different and also the diagnosis …. so, be careful.

e) Patient gender;

 This is necessary because the reference value ranges for some tests depends on the gender; male or female and if the gender is faulty recorded then the reference values of some tests will be different and also the diagnosis

 f) The Physician Name and Telephone:

This really very important  because you may find that the test result is abnormal and you may know that this means a bad condition so, you need to call the patient physician to ask him about the diagnosis to make sure that the result is reliable or not.

Also according the test results, you may expect that the result you seen is abnormally high due to some medication so, you need to call the physician to make that the result is correct.

Also you may need to call the physician to tell him the his patient is not prepared for the test …. you may say that is weird!!! ….. Actually i face a situation like this; a male patient came to my lab and this physician wants a semen processing for artificial insemination .. but the patient should not intercourse with his wife for at least 3 days but what the patient actually do is that he do intercourse with his wife the day before he came to my lab and the result is a semen specimen that is less than 1 ml and of course i refused the sample and call the patient doctor to tell him that it his patient intercourse with his wife yesterday and it is impossible to do the test.

g) If the patient is pregnant (for female only of course):

This is because the results of some tests are affected by pregnancy … and be careful don’t ask this question for male patient.

II) Data that are required in case of some tests:-

Some data are required for some tests such as fasting for fast blood sugar …. let’s see.

a) Fasting:-

There are tests that require fasting such as fast blood sugar (FBS) which require fasting for 6 to 8 hours and also cholesterol and Triglycrides which require fasting for 12 to 14 hours.

Also, fasting may affect other substances in blood for example:

  • In case of glucose and triglycerides absorbed from food, both are increased after eating …. and after fasting for 48 hours, bilirubin increases.
  • Fasting for 72 hours reduce sugar level in healthy women 45 mg/dl but in men plasma triglycerides, fatty acids and glycerols increased and cholesterol is normal.

b) Medication:-

This is important for some tests such as blood sugar test (fast and postprandial and random blood sugar tests) which is affected by the medication for balancing sugar levels in blood.

Also Prothrombin time, partial thromboplastin time, bleeding test and clotting test are affected by medication for blood coagulation and in this case it is important to know the medication and the dosage and also  the change in dosage and the date of the change.

Also when the physician wants a culture for his patient whatever the culture type, you should know if the patient takes antibiotic in the last 48 hours or not?? …. the patient shouldn’t take antibiotics for 48 hours before culture test and of course if he take antibiotic before the culture test, you should tell the physician and you can do it or you can do it on the patient and physician responsibility.

c) Blood transfusion:

Because if the patient receive blood from blood transfusion recently this affect the result for most tests especially Hb and blood indices.

d) The first day in the last Menstrual cycle:

This is important in case of pregnancy test.

e) If X-ray with dye is done:

Because the dye affect some tests especially urine analysis and X-ray affect hormones.

These are almost the common data you should collect but what about diet and smoking …. You may find that it is silly to ask the patient what did you eat from 2 hours? and the patient may be agree with you and also if you ask the patient if he smokes cigarettes or not, the patient may ask you how this be useful in my test?

Actually diet and smoking affect the results of some tests …. let’s see some examples.

1) In Case of Diet:

Of course the effect of diet on tests results is transient and can be controlled easy …. for example:-

  • High fat content meal may elevate plasma potassium, alkaline phosphatase and triglycerides.
  • Meat, iron, fish affect stool occult blood tests… also horseradish which is a source of peroxidase cause a false positive occult blood reaction.
  • Be a vegeterian for long time decreases the concentrations of low-density lipoproteins (LDLs), very low-density lipoproteins (VLDLs), phospholipids, totla lipids, triglycerides, cholesterol and vitamin B12.
  • High meat meal or protein rich diet may increase serum urea, urate and ammonia.
  • High protein and low carbohydrate diets greatly increase ketones in the urine and increases serum blood urea nitrogen (BUN).
  • Caffeine elevates plasma free fatty acids.

There are more examples but it is prefered to know what the patient eats brfore come to you and write it in your report to because if you don’t know the effect of the diet, the physician may know and consider this when reading the results.

2) In case of smoking of cigarettes:

  • Smoking elevates the levels of carboxyhemoglobin, plama catecholamines and serum cortisol which are hormones and this leads to decrements the numbers of eosinophils and increment of neutrophils, monocytes and plasma free fatty acids.
  • Smoking increases Hb concentration, RBCs count, MCV and WBCs count.
  • High lactate, insulin, epinephrine and growth hormone can be seen.
  • Vitmanin B12 levels may be decreased substantially in smokers which is inversely proportional to thiocyanate levels which is toxic.
  • Immunoglobuilin IgA, IgG and IgM are lower in smokers but IgE levels are higher.
  • Decreased sperm counts and motility in male smokers and increased abnormal morphology.

Also if you don’t know the effect of smoking on the test results it is better to write this as note for the physician.

From these data you can make the board form you need with any style you like and then input these data to your lab software on your computer.

Please follow the sample collection topics from the menu bar MEDICINE>>CLINICAL LABORATORY TESTS>>SAMPLE COLLECTION … every while we add an new topic until it done


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