Peripheral Smear Examination
What is P/S?
The peripheral smear examination (P/S) is also known as blood smear, blood film, manual differential, differential slide, red blood cell morphology, erythrocyte morphology, and leukocyte differential test. This test is done to evaluate the different components of the blood.
Why is P/S done?
The peripheral smear examination is done:
In case of signs or symptoms of anemia such as weakness, fatigue, pale complexion, unexplained jaundice, and enlargement of the spleen.
In case the results of complete blood count or WBC differential is abnormal.
In case of signs or symptoms of conditions affecting red blood cell production.
What does P/S Measure?
The peripheral smear examination evaluates the red blood cells (RBCs), white blood cells (WBCs), platelets and determines their relative percentages in the blood. It also helps in detecting, diagnosing, and monitoring deficiencies. Along with that, it detects diseases and disorders which involves the production of blood cells, their function, and lifespan.
To make a peripheral smear, a drop of blood is taken from the patient’s blood sample and is spread in a thin layer onto a glass slide. The slide is then stained with special stains. After the staining, the slide is examined and evaluated under the microscope for blood cells.
The following cells can be evaluated in the slide:
White blood cells (WBCs or leukocytes) - Their function is to fight infections and participate in immune responses.
Red blood cells (RBCs, erythrocytes) - Their function is to carry oxygen to the tissues.
Platelets (Thrombocytes) - These are small cell fragments which play an important role in blood clotting.
Platelets are produced and mainly mature in the bone marrow just like RBCs and WBCs. They are released into the stream of blood whenever required.
The peripheral smear examination helps to:
Compare the size, shape, and general appearance of WBCs along with determining its five different types and their relative percentages.
Detects the size, shape, and color of the RBCs.
Evaluates the number of platelets.
The number and the appearance of blood cells can be affected by a variety of diseases and conditions such as the smaller size of RBCs may indicate a type of anemia, increased number of WBCs may indicate infection or any other condition.
Interpreting P/S results
The abnormal results depend upon the type of blood cell affected.
The abnormal red blood cells can be seen in conditions like:
Iron deficiency anemia
Sickle cell anemia
Hemolytic uremic syndrome
Polycythemia rubra vera
The abnormal white blood cells can be seen in conditions like:
Acute or chronic leukemia
Hepatitis C virus infection
Fungal infections such as candidiasis
Parasitic infections such as pinworm
Other lymphoproliferative diseases
The abnormal platelets can be seen in conditions like: