An inherited blood disorder where red blood cells (RBCs) become sickle/crescent shaped. It causes frequent infections, swelling in the hands and legs, pain, severe tiredness, and delayed growth or puberty.

1. Sickle cell test

2. Introduction
• sickle cell test 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.

3. General Principle
In a conditions at which oxygen tension decline to induced the sickling
process of Hbs in RBCs.

4. 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

5. Specimen:
• Whole blood using 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.

6. Procedure:
• Place one drop 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

7. saline citrate with paraffin 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.