Blog Articles

Everything you need to know about sampling

21 December 2020

1. Should I be fasting before the analysis?

In general, the patient should be fasting for at least 8 hours for their analysis, although some require more prolonged fasting, of at least 12 hours, particularly for the Cholesterol Total analysis and its fractions, Triglycerides and Lipid Profile.

There are, however, several analyses that do not require fasting, such as viral, hormonal, bacteriological, allergic or immunological analyses. You should always ask your attending physician or laboratory to explain how you should proceed. If in doubt, and if for some reason you are unable to clear your doubts, you should always opt for fasting.

2. How much blood is extracted during the sampling?

The collected blood amount may vary widely depending on the number and the type of analysis requested by the physician. However, the sample is usually about 6 to 9 mL of blood.

3. Is there anything I should tell the technician responsible for the sampling?

Any and all information is important and useful to the technician, but the most important is: if you ever felt indisposed or even fainted in previous samplings, if you have any health condition that may affect the sample or its analysis, if you are taking any medication that may interfere with the analysis or the blood sampling, particularly anticoagulants, which increase the time it takes to staunch the sting site.

4. Why did I get a bruise after the blood sampling?

Although it is not very common, sometimes there can be a blood leak under the skin, thus forming the hematoma.

A hematoma is a collection of blood within a tissue. In other words, when the blood escapes its natural environment – the blood vessels – and gathers significantly between the cells of a particular organ or tissue, a hematoma occurs. When this phenomenon occurs on the skin or in the structures situated immediately below it, it is referred to as ecchymosis, commonly known as ‘bruise’.

The appearance of a hematoma may be due to several factors, including:

  • Inadequate compression of the puncture site;
  • Extremely thin veins;
  • Difficult sampling;
  • Drug interference.

Some people are more prone to develop hematomas, often getting a hematoma at the puncture site.

To prevent bruising, the puncture site should you should be pressed with dry cotton for one to two minutes, and you should avoid exerting your arm in the following minutes.

5. Can I drink water before the sampling?

Yes, there is no problem in drinking water in moderation before your analysis, as this will not affect the results. You should not, however, drink it in excess, as that could change the result of the urine test. Do not drink, or eat, anything other than water.

6. Can I smoke before my analysis?

No, you should not smoke before the analysis. Smoking beforehand will affect the results of some tests, therefore you should abstain from smoking for in the hours prior to the blood sampling, just as you do with food.

7. Can I take my usual medication?

There are several medications that interfere with blood analyses, such as antibiotics, anti-inflammatory drugs, among others. However, you should not stop taking medication without medical advice. You should tell the technician that you are under certain medication so that he can correctly read analyses, taking this factor into account.

8. Can I do the tests when I’m menstruating?

Yes, you can. However, the physician should be made aware that you were menstruating at the time of the sample collection, due to hormonal changes and certain serum proteins.

It is not recommended to do the analysis of urine and vaginal exudates, because the blood will mix with the sample. The samples for these tests should, therefore, only be done when the menstrual period is completely over unless the sampling is extremely urgent.

9. How long until my analyses are ready?

At registration, the user is informed of the time it will take until the analyses are ready, taking into account which ones were requested by the physician. Nevertheless, the most common processing time is approximately one week, after which your results will be delivered at your health care centre.

However, there are tests whose results are available on the same day and others, highly specific ones, which can take more than eight days.

10. Why are my results late?

In exceptional cases, there may be delays in delivering results. This delay may be due to a number of situations, such as:

  • Insufficient sample;
  • Sampling may have to be repeated to confirm the results;
  • Sporadic technical problem.

11. I was told I needed to repeat the sampling. Will there be additional costs for me?

No, if the sample was insufficient, if the sampling was incorrectly performed or if it is necessary to repeat it to confirm the results, there are no additional costs to what you have already paid for at registration.

12. Should I be tested regularly?

Clinical analyses are complementary diagnostic tests, which, coupled with other tests and the patient’s medical history, serve to confirm or disprove a diagnosis. However, you should not get tested only when you are ill or showing symptoms. You should be tested regularly, at least once or twice every year, as there are diseases that do not show any distinct symptoms at an early or advanced stage.

Clinical analyses can be requested for different situations, namely for a simple check-up, to monitor certain diseases (e.g. diabetes), to confirm or disprove a diagnosis and early detection of many diseases, allowing the doctor to treat them early, increasing the possibility of healing them.

13. From which parts of the body can blood be collected for analysis?

The best spot for blood collection is in the antecubital fossa of the arm, but it can also be done in the forearm or hands. There are also individual cases where it may be necessary to resort to other collection sites, such as the elbow, feet or ankles.

14. My veins are very hard to find. What can I do to facilitate their surfacing?

It is not always easy for the technician to find superficial veins to puncture, especially in babies or in some people who have undergone aggressive treatments, such as chemotherapy.

In order to help the veins surface, you can place a warm cloth on your arm or exercise it a bit, by holding a relatively heavy bucket, for example, which will dilate the arm veins due to exercise or heat, facilitating their visibility on the skin.

15. How do I know what I should take with me and if I should be fasting?

You should always ask your attending physician to explain what you are going to do and how you should prepare for the tests. If that does not happen or if you have any doubts, you should contact Aqualab so that we can explain the conditions and care required to perform the requested analyses.

Due to the variety of available analyses, there are several possible scenarios, however, the most common is that the person should be fasting for a minimum of 12 hours.

16. Can I take a urine sample home or should I do it at the laboratory?

Ideally, the sample should be taken at the laboratory. However, for your own comfort, you can bring a sample from home, using a sterile container and suitable for storing urine.

You should be aware, however, that the sample required is not always from the first urine of the morning (Urine II), but rather a sample of an Aseptic Urine. This implies specific care and should be taken at the laboratory. You can stop by Aqualab, where the container will be provided or you can buy it at a pharmacy near you.

17. What are Type II Urine and Aseptic Urine?

Type II Urine is used in the morphological, physical and chemical analysis of urine.

Aseptic Urine is the collection of the urine with all the aseptic precautions, used for the detection of urinary tract infections caused by bacteria.

For either one, the preferred sample is always the first urine of the morning, as it is at its most concentrated form. However, both samples can be collected at any time of day, but the aseptic urine should be collected at the laboratory.

18. How can you ensure that there are no swaps and how are the samples identified with my data?

At registration, the patient is given a unique identification number in the laboratory, which allows us to access the data provided by the user. Every sample is identified during the sampling with tags containing the bar code with the ID number previously assigned.

Due to the wide automation of the laboratory’s equipment, the apparatus reads the bar code while analysing the sample, and assigns the result to the appropriate number, thus ensuring that there are no exchanges between patients’ results.

19. What can happen to make it necessary to perform a new sampling?

In certain occasional situations, the user can be reconvened to perform a new sampling. There are a few situations that can lead to this, the most common is an insufficient blood sample, due to a difficult collection, but there are others:

  • To confirm a result;
  • In prolonged collections, the blood can eventually coagulate, changing the results;
  • In difficult collections hemolysis may occur in the sample, causing some parameters to change;
  • Incorrect sampling (e.g. contamination of an aseptic urine sample).

Among others, such as human or technical error.