Sickle cell test.pptx

Sickle cell test.pptx

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  Sickle cell test
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  Introduction • sickle celltest is a blood test done to screen for sickle cell trait or sickle cell disease. • Sickle cell disease is an inherited blood disease that causes red blood cells to be deformed (sickle_x0002_shaped). • If the screening test is negative, it means that the gene for sickle cell trait is not present. • If the screening test is positive, then further haemoglobin testing must be performed to confirm whether one mutated gene or both are present. • In unaffected individuals HbS is not present.
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  General Principle In aconditions at which oxygen tension decline to induced the sickling process of Hbs in RBCs.
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  Sodium Metabisulfite Method Principle •When a drop of blood is sealed between a cover slip and a slide, the decline in oxygen tension due to oxidative processes in the blood cells leads to sickling. • In this method added with blood drop a chemical reducing agents. • Such as sodium metabisulfite. • This rapidly reduces oxyhemoglobin to reduced hemoglobin, then this will beaccelerate sickling
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  Specimen: • Whole bloodusing heparin or EDTA as anticoagulant. Capillary blood may also be used. Reagent and equipment: • 1. Sodium Metabisulfite 2% (w/v); prepared by dissolving 0.2 gm sodium metabisulfite • in 10 ml DW. Stable for 8 hours at room temperature. • 2. Petroleum jelly. • 3. Cover glass. • 4. Microscope.
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  Procedure: • Place onedrop of the blood to be tested in a glass slide. • Add 1- 2 drops of sodium metabisulfite to the drop of blood and mix well with an applicator stick. • Place a cover glass on top of the sample and press down lightly on it to remove any air bubbles and to form a thin layer of the mixture. Wipe of the excess sample. • Carefully rim the cover gloss with the petroleum jelly, completely sealing the mixture under the cover slip. • Examine the preparation for the presence of sickle cells after one hour using 40 X objective. In some instances, the red blood cells may take on a holly-leaf form. This hape is found in sickle cell trait, and, when present, the test is reported as positive. • If there is no sickling present at the end of one hour, allow the preparation to stand at room temperature for 24 hours, and examined at that time. • When sickle cells or the holly leaf form of the cells are present the results are reported as positive. Normal looking red cells or slightly crenated red blood cells
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  saline citrate withparaffin oil Principle: • a saline citrate suspension of blood is allowed to stand in a test tube under a layer of paraffin oil until sickling takes place.’ • In employing any of the common diagnostic tests for sickling it is desirable to obtain blood which has a low fraction of oxyhemoglobin.