sickle cell test , Principal, Procedure of sickle cell , Interpretation

Sickle cell test

TEST FOR SICKLE CELLS

Principal

Specimen

Technique 

Procedure  of sickle cell 

 Interpretation

 

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TEST FOR SICKLE CELLS:- In homozygous sickle cell anaemia, the sickle cells may be seen in the peripheral blood smear, and the diagnosis can be made from the clinical and haematological picture. However, in heterozygous sickle cell trait, these changes are not apparent and diagnosis is difficult. In such cases, if the whole blood is exposed to reduced oxygen tension with the help of a reducing agent, sickling can be demonstrated.

Specimen: A fresh anticoagulated blood sample. A normal blood specimen should be used as a control. 

Reagent : A freshly prepared solution of 2% sodium metabisulphite. Dissolve 0.2 g in 10ml distilled water. 

Technique

 (i) Add 0.5 ml of whole blood to 0.5 ml of 2%sodium metabisulphite in a test tube.

(ii) Mix thoroughly and place a drop on a glassslide, cover with a coverslip. Seal all the four edges with vaseline.

(iii) Leave at room temperature for one hour.

(iv) Observe the red cell morphology under the microscope.

 (v) Proceed with the control in the same way.

Interpretation The control shows normal red cells which retain their biconcave discoid shape in the presence of sodium metabisulphite. In sickle cell trait, the red cells lose their characteristic morphology due to reduced oxygen tension in the presence of sodium metabisulphite and some cells may appear crescent-shaped (Fig. 5.3).