What is the Peripheral Smear (Blood Picture) test? 

A peripheral smear test determines the different components of the blood. The smear evaluates the red blood cells (RBC), white blood cells (WBC), and platelets as well as any other abnormalities, such as the presence of parasites. A blood smear test is ordered to diagnose the causes of unexplained jaundice, unexplained anaemia, unknown fever, and severe infection in the body.

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The number and appearance of the blood cells can be affected by several diseases. For example, smaller size of RBCs can indicate a type of anaemia, whereas increased number of WBCs might indicate infection.

A blood smear test is considered normal when the sample contains the optimum number, size, and shape of the blood cells. The results are considered abnormal when cells have an abnormality in shape, size, or number.

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What are the other names for the Peripheral Smear (Blood Picture) test? 

The other names are Blood Picture, PBS Test, Peripheral Blood Film, and Blood Morphology Test. 

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What are the test parameters included in the Peripheral Smear (Blood Picture) test?

There is only one parameter.

What does a Peripheral smear (Blood Picture) test measure?

A blood smear is a study of the cells that are present in the blood at the time the sample is collected. The blood smear allows for the determination of these cells:

• White blood cells (WBCs or leukocytes) help to fight infections or are present in the immune response.

• Red blood cells (RBCs, erythrocytes) carry oxygen to the tissues across the body.

• Platelets (thrombocytes) are tiny cell fragments that are very vital for proper blood clotting. 

These cell populations are manufactured and mainly mature in the bone marrow and are eventually released into the bloodstream as required. The number and type of each cell present in the blood are dynamic, but they are generally maintained by the body within specific ranges. 

The small drop of blood on the slide used for a blood smear contains millions of RBCs, thousands of WBCs, and hundreds of thousands of platelets. The blood smear examination is as follows:

• It evaluates WBC’s size, shape, and appearance.It also defines five types of WBCs and their relative percentages (WBC manual differential counts).

• It evaluates the size, shape, and colour (indicators of haemoglobin content) of the RBCs or RBC morphologies.

• Estimates the total number of platelets present in the smear.

Different types of diseases and conditions can affect the number and appearance of blood cells. The examination of the blood smear can be used to support the findings from other tests and examinations. For example, RBCs that appear smaller and paler than normal may be associated with other results that indicate a type of anaemia. Similarly, the presence of WBCs that are not fully mature may add to the information from the other tests to help make a diagnosis of infection, malignancy, or other conditions.    

What’s the normal range of Peripheral smear (Blood Picture)? 

A blood smear is considered normal when your blood contains a sufficient number of cells; that is, the differential count should be 100 cells, including all five types of WBCs; the total WBC count should be between 4000 and 11000 cells, and the cells should have a normal appearance. A blood smear is considered abnormal when the size, shape, colour, or number of cells in your blood is not normal.

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Who should get a Peripheral Smear (Blood Picture) test? 

Usually, the blood smear is primarily recommended as a follow-up test when a CBC test with the differential count is performed with an automated blood cell counter, and it indicates the presence of atypical, abnormal, or immature cells. This may also be performed when a person has signs and symptoms that suggest a condition is affecting blood cell production or the lifespan.

The signs and symptoms which might indicate one of these blood disorders include:

• Weakness, fatigue

• Pale skin complexion

• Unexplained jaundice, that is, yellowing of the skin and the whites of the eyes.

• Fever

• Excessive bleeding episodes, easy bruising, or frequent nose bleeds.

• Enlargement of the spleen

• Bone pain

A blood smear can also be ordered on a regular basis when a person is being treated or monitored for a blood cell-related disease.

Are there any preparations needed for the Peripheral Smear (Blood Picture) test?

No special preparation is required. Fasting is not required for this test. Please ask the doctor if there are any precautions to be taken.

What is the cost of a Peripheral Smear (Blood Picture) test?

What is the type of sample required? 

This test requires a blood sample.

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Who processes the Peripheral Smear (Blood Picture) test?

A healthcare provider, who is also called a phlebotomist, usually performs blood draws, including those for peripheral smear tests, but any healthcare provider trained in drawing blood can perform this task. These samples are sent to a lab where a medical laboratory scientist prepares the samples and performs the tests on analysers or manually.

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What should I expect during my Peripheral Smear (Blood Picture) test?

You can expect to experience the following during the blood test or a blood draw:

• You can feel the experience of the following during the blood test or blood draw.

• You have to sit comfortably on the chair, and the phlebotomist will check your arms for an easily accessible vein. This is the inner part of your arm on the other side of your elbow.

• Once the phlebotomist has located a vein, they will disinfect the area with an alcohol swab.

• They will insert the needle into your vein to draw a blood sample. This might feel like a small pinch.

• After they insert the needle, the required amount of blood will be drawn into a test tube.

• When they have drawn enough blood for the test, they’ll remove the needle and hold a cotton ball or gauze on the site to stop any bleeding.

• They will apply a band-aid over the pricked site, and the blood collection is finished.

This process takes less than five minutes.

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What should I expect after my Peripheral Smear (Blood Picture) test?

Once the phlebotomist has collected the blood sample, it will be sent to the laboratory for processing or testing. When the reports are ready, your healthcare provider will share the results with you.

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What are the risks of a Peripheral Smear (Blood Picture) test?

These blood tests are common, and they don’t carry any significant risks. You might have a slight pain like an ant bite when the needle gets inserted, and a small bruise can develop there.

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When can I expect my Peripheral Smear (Blood Picture) test results?

At Orange Health, peripheral smear test reports are available within 6 hours.

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What do the results of a Peripheral Smear (Blood Picture) test mean? 

Interpretation

Microscopic findings from blood smear evaluation are not always diagnostic in themselves and more often indicate the possibility or presence of an underlying condition, its severity, and the need for further diagnostic testing. These results are taken into consideration with the results of the CBC and other diagnostic tests as well as the tested person's clinical history of symptoms.

The results of a blood smear typically include a description of the appearance of the red blood cells, white blood cells, and platelets as well as any abnormalities that might be seen on the slide.

Red Blood Cells (RBCs)

Normal, mature red blood cells are uniform in size (7-8µm in diameter) and do not have a nucleus as most other cells do. They are round and flattened like a donut with a depression in the centre instead of a hole or biconcave. It is due to the haemoglobin inside the RBCs that they appear pink to red in colour with a pale centre after staining with the blood smear. When the appearance of RBCs (RBC morphology) is normal, it is often reported as a normochromic and normocytic blood picture.

While not every RBC will be perfect, any significant number of cells that are different in shape or size can indicate the presence of disease. Some of the examples of conditions that may affect red blood cells include:

• Anaemia

• Haemoglobin variants include sickle cell anaemia and thalassemia.

• Leukaemia

• Myeloproliferative or myelodysplastic neoplasms

• Bone marrow disorders

There can be one or more RBC irregularities seen on a blood smear. Two examples include

• Anisocytosis: Variable sizes of red blood cells can indicate anaemia; RBCs smaller than normal are referred to as microcytes, and RBCs larger than normal are called macrocytes.

• Poikilocytosis: Several shapes of red cells may include burr cells (echinocytes), acanthocytes, elliptocytes, rouleaux, sickle cells, target cells, teardrop cells, and schistocytes (red cell fragments, helmet cells).

• Anisopoikilocytosis: variability in both RBC size and shape.

White Blood Cells (WBCs)

A manual WBC differential can be performed as a part of a blood smear evaluation. Typically, at least 100 WBCs are evaluated and categorised according to type. The percentage of each type is calculated. In addition to this, the appearance (morphology) and the stage of development of the WBCs are noted.

Numerous diseases and conditions may affect the absolute or relative number of WBCs and their appearance on a blood smear. Some of the conditions include

• Infections and or inflammation - which may increase certain types of WBCs.

• Bone marrow disorders - depending on the condition, can increase or decrease absolute and relative numbers of WBCs.

• Allergies - can affect the number of eosinophils.

• In leukaemia, myelodysplastic syndrome, or myeloproliferative neoplasm,- immature white blood cells such as blasts can be seen on the blood smear’ blasts are normally found in the bone marrow where WBCs are manufactured and mature before being released into the blood. If blasts are seen on a blood smear, they can indicate a serious bone marrow disease. They can also be seen in other scenarios, such as when the bone marrow is recovering or regenerating from chemotherapy, or as another example, stimulated by a medication prior to stem cell collection.

Platelets

There are cell fragments that have developed from large bone marrow called megakaryocytes. Upon release from the bone marrow, they appear as fragments in the peripheral blood. When there is blood vessel injury or another bleeding, the platelets become activated and begin to clump together to form aggregates, which is the beginning of a blood clot.  

There must be a sufficient number of platelets to control bleeding. If there are too few, or if they don’t function properly, the ability to form a clot becomes impaired and can be a life-threatening situation. In some people, too many platelets may be produced, which can result in interference with the flow of blood, increasing a person’s risk of developing a blood clot. These same people can also experience bleeding because many of the extra platelets may be dysfunctional even though they appear normal.

A platelet count is usually part of a CBC. An abnormally low number or the high number of platelets can be further determined by preparing a blood smear to directly visualise any anomalies in shape or size. For example, the large platelets or giant platelets can be seen as the bone marrow tries to compensate for a low platelet count, but they can also be seen in myeloproliferative neoplasms or immune thrombocytopenia, a condition in which the immune system inappropriately produces antibodies directed against the platelets.

What are normal Peripheral Smear (Blood Picture) test results?

The doctor will check the blood smear under the microscope. A blood smear is considered normal when your blood contains a sufficient number of cells and the cells have a normal appearance. A blood smear is considered abnormal when the size, shape, colour, or number of cells in your blood is not normal.

The normal ranges can vary slightly among different laboratories. Some of the labs use different measurements or might do tests on the different samples. Speak to your healthcare provider about the meaning of your specific test results.

What other tests might I have along with this test?

Complete Haemogram

How do I book a Peripheral Smear (Blood Picture) test at home?

Log on to www.orangehealth.in and submit your details. Our highly trained, professional, and vaccinated eMedics will be at your doorstep within 60 minutes or at the time booked by you.