Is a Blood Smear?
A blood smear is
a blood test used to look for abnormalities in blood cells. The three main blood
cells that the test focuses on are:
cells, which carry oxygen throughout the body
cells, which help your body fight infections
which are important for blood clotting
The test provides information on the number and shape of these cells,
which can help doctors diagnose certain blood disorders or other medical
Irregularities in the number or shape of your red blood cells can
affect how oxygen travels in your blood. These abnormalities are often caused
by a mineral or vitamin deficiency, but they can also be caused by certain
medical conditions, such as sickle
White blood cells are an integral part of your body’s immune system, which is a network of
tissues and cells that help your body fight infection. Having too many or too few
white blood cells can indicate a blood disorder. Disorders affecting these
cells often result in the body’s inability to eliminate or control infections.
Abnormalities in the
shape or number of white blood cells may be signs of a platelet disorder.
Platelet disorders affect your blood’s ability to clot, which can lead to
excessive or prolonged bleeding. They often occur when the body produces too
many or too few platelets.
Is a Blood Smear Done?
The blood smear test is often done to diagnose conditions that
- unexplained jaundice
- unexplained anemia, or low levels of red blood
- abnormal bruising
- persistent flu-like symptoms
- sudden weight loss
- unexpected or severe infection
- skin rashes or cuts
- bone pain
Should I Do Before a Blood Smear?
Before the test, it’s important to tell your doctor about any prescription
or over-the-counter medications, supplements, and vitamins you’re currently
taking. Certain medications can affect your test results. These include anticoagulants,
such as warfarin,
acenocoumarol, and atromentin.
You should also tell your doctor about any existing medical
conditions, such as hemophilia. Certain disorders, regular blood transfusions, and
the presence of blood cancer will produce abnormalities on the blood smear.
It’s important to discuss these matters with your doctor before the
blood smear to avoid a possible diagnostic error.
Happens During a Blood Smear?
The blood smear is a simple blood test. A phlebotomist, a person specifically trained
to draw blood, will clean and sterilize the injection site with an antiseptic.
They’ll then tie a band above the site where your blood will be drawn. This
will cause your veins to swell with blood. Once they find a vein, the
phlebotomist will insert a needle directly into the vein and draw blood.
Most people feel a sharp pain when the needle first goes in, but
this quickly fades as the blood is drawn. Within a couple of minutes, they’ll
remove the needle and you’ll be asked to apply pressure to the site with gauze
or a cotton ball. A bandage will then be placed over the puncture wound and
you’ll be free to leave.
A blood test is a low-risk procedure. However, minor risks
- fainting from the sight of blood, or vasovagal
- dizziness or vertigo
- soreness or redness at the puncture site
Do the Results Mean?
A blood smear is considered normal when your blood contains a
sufficient number of cells and if the cells have a normal appearance. A blood
smear is considered abnormal when there’s an abnormality in the size, shape, or
number of cells in your blood. Abnormal results may vary depending on the type
of blood cell affected.
Red blood cell type disorders include:
White blood cell disorders include:
leukemia, which is a type of blood cancer
- lymphoma, which is a form
of cancer that affects the immune system
- HIV, which is a virus that
infects the white blood cells
- a hepatitis C infection
- parasitic infections, such as pinworm
- fungal infections, such as candidiasis
- lymphoproliferative disorders, such as
follicular lymphoma and multiple myeloma
Disorders affecting platelets include:
- myeloproliferative disorders, which are a group
of disorders that cause blood cells to grow abnormally in the bone marrow
- thrombocytopenia, which occurs when the number
of platelets is very low due to an infection or other disease
A blood smear can also indicate other conditions, including:
Normal and abnormal ranges can vary among labs because some use
different instruments or methods to analyze the blood sample. You should always
discuss your results in more detail with your doctor. They’ll be able to tell
you if you need more testing.