WET FILM PREPARATION METHODOLOGY IN HAMATOLOGY | MATERIALS | PROCEDURES | PRECAUTIONS

WET FILM PREPARATION

In hematology, it is most important to know that wet films are also made for hematological analysis. Wet films are made in sickling test analysis and in rough estimation of platelets and white blood cell.

WET PREPARATION FOR WHITE BLOOD CELL COUNT

Materials Used:

·        Test tube

·        Improved Neubauer counting chamber

·        Blood sample

·        Automatic pipette

·        Cotton wool

·        Cover slip

·        Turks solution

Procedure:

·        1:20 dilution of the blood is prepared in the diluting fluid (Turk solution) in a test tube.

·        The improved Neubauer counting chamber is charge by moisturizing the chamber a little and sliding up by the cover slip to form a Newton ring.

·        With the help of the automation pipette filler, the grids of the charged improved Neubauer counting chamber is filled with the diluted sample and allowed to settle.

·        Precaution is to be taken to ensure that the grid is not over filled

·        The cells are allowed to settle in a moist chamber (e.g. a cotton wool -moist petri dish with cover) for 3-5 minutes (Ochei and Kolhatkar, 2007).   

WET PREPARATION FOR PLATELET COUNT

Materials Used:

·        New improved Neubauer counting chamber

·        Test tube

·        Automatic pipette

·        Ammonium oxalate (diluents)

Procedure:

·        A dilution of 1:200 of the whole blood and the diluent is made in a test tube.

·        The improved Neubauer counting chamber is charged

·        With the automatic pipette, fill the grids of the counting chamber.

·        Allow the platelets to settle in a moist chamber for 2-3 minutes(Ochei and Kolhatkar, 2007).   

GENERAL PRECAUTIONS TAKEN WHILE MAKING FILMS IN HEMATOLOGY:

1.   The slide must be well cleaned, grease-free and dust free

2.   The spreader must be smooth

3.   Ensure that the surface of the slide is water free

4.   Do not overfill the grid of the improved Neubauer counting chamber

5.   Do not fill the two grids of the improved Neubauer counting chamber, only one grid is to be filled

6.   Ensure neat working environment is maintained.

7.   Label the slide properly for identification and good laboratory management

8.   2 smears at least, must be made for a particular sample to ensure accuracy and good result (Ochei and Kolhatkar, 2007).   

WET PREPARATION FOR SICKLING TEST

Materials used:

·        A fresh anticoagulated blood sample

·        A normal blood sample for control

·        A freshly prepared solution of 2% sodium metabisulphite.

·        10ml distilled water

·        Test tube

·        Pasture pipette

·        Glass slide

·        Cover slip

·        Vaseline

Procedure:

·        Dissolve 0.2g of 2% sodium metabisulphite in 10ml distilled water

·        Add 0.5ml of whole blood to 0.5ml 2% sodium metabisulphite in a test tube

·        Mix thoroughly and place a drop on a glass slide, cover with coverslip. Seal all the four edges with Vaseline.

·        Leave at room temperature for 1hour

·        Observe the red cell morphology under the microscope.

·        Proceed with the control in the same way (Ochei and Kolhatkar, 2007).