7 Difference Between Thick Blood Smear And Thin Blood Smear

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Thick and thin blood smears are commonly used to determine whether a person has malaria or not. If one test is negative and no parasites are found, there will be repeated blood smears every 8 hours for a couple of days to confirm that there is no malaria infection. Blood smears are most often taken from a finger prick. Thick and thin blood smears will let doctors know the percentage of red blood cells that are infected (parasite density) and what type of parasites are present.

What Is Thick Blood Smear?

A thick blood smear is a drop of blood on a glass slide. Thick blood smears are most useful for detecting the presence of parasites, because they examine a larger sample of blood. A thick blood film smear requires a large volume of blood as compared to thin blood films which enable the more efficient detection of parasites in the blood specimen. A thick blood smear is made by spreading a large blood drop in a small area of about 1 cm which provides a better opportunity to detect various parasitic forms against a more transparent background.

What You Need To Know About Thick Blood Smear

  • A thick blood smear is a drop of blood on a glass slide.
  • Thick blood smears are useful for detecting the presence of parasites because they examine a larger sample of blood.
  • The blood films must be laked before or during staining to rapture all the RBC so that only WBC, platelets and parasites are visualized.
  • Thick smears allow a more efficient detection of parasites (increased sensitivity 11 times than thin smear).
  • It is not fixed in methanol.
  • Thick smears are mainly used to detect infection and to estimate parasitemia.
  • Save time in examination.

What Is Thin Blood Smear?

A thin blood smear is a drop of blood that is spread across a larger area of the slide. Thin blood smears help doctors discover what species of malaria is causing the infection. The thin blood smear is made by placing a well-mixed drop of blood 1 to 2 mm in diameter and ΒΌ inch from the edge of the clean microscopic glass slide. The drop should be in the center line of the glass slide. These margins are left onto the glass slide slide to get a region where the cells are spaced far enough apart to be counted and differentiated. Using a second slide as the spreader, the blood is streaked into a thin film in the tongue-like shape and allows to dry. The blood smear is then fixed and stained with Romanowski stain for microscopic examination.

What You Need To Know About Thin Blood Smear

  • A thin blood smear is a drop of blood that is spread across a large area of the slide.
  • Thin blood smears help to discover which species of parasite is causing the infection.
  • The purpose is to allow malarial parasites to be seen within the RBC and to assess the size of the infected RBCs compared to uninfected RBCs.
  • Less sensitive than a thick film especially where there is a low parasitemia.
  • It is fixed in methanol.
  • Thin smears allow the examiner to identify malaria species, quantify parasitemia and recognize parasite forms like schizonts and gametocytes.
  • Requires more time to read.

Difference Between Thick Blood Smear And Thin Blood Smear In Tabular Form

BASIS OF COMPARISON THICK BLOOD SMEAR THIN BLOOD SMEAR
Description A thick blood smear is a drop of blood on a glass slide.   A thin blood smear is a drop of blood that is spread across a large area of the slide.  
Use Thick blood smears are useful for detecting the presence of parasites because they examine a larger sample of blood.   Thin blood smears help to discover which species of parasite is causing the infection.  
RBC Analysis The blood films must be laked before or during staining to rapture all the RBC so that only WBC, platelets and parasites are visualized.   The purpose is to allow malarial parasites to be seen within the RBC and to assess the size of the infected RBCs compared to uninfected RBCs.  
Sensitivity Thick smears allow a more efficient detection of parasites (increased sensitivity 11 times than thin smear).   Less sensitive than a thick film especially where there is a low parasitemia.  
Methanol It is not fixed in methanol.   It is fixed in methanol.  
Importance Thick smears are mainly used to detect infection and to estimate parasitemia.   Thin smears allow the examiner to identify malaria species, quantify parasitemia and recognize parasite forms like schizonts and gametocytes.  
Examination Time Save time in examination.   Requires more time to read.