www.phclab.com

The Public Health Care Laboratory 

    

phclab.com

The website for laboratory personnel in developing countries

Back

Standard Operating Procedures (SOPs)

Example SOP

ERYTHROCYTE SEDIMENTATION RATE (ESR)

WESTERGREN METHOD

A 001

Page 1

Authorised signature:

Issuing Date: April 12, 2000

Next Revision Date: April 12, 2001

Staff able to perform test:     Laboratory Assistant and higher
Principle of the Test Method

The ESR expresses in mm per hour the rate at which red blood cells settle when anti-coagulated blood is allowed to stand in a narrow tube (Westergren).  It is shown by the height of the column of clear plasma at the end of one hour.

Clinical Significance of the Test:

ESR is used as a screening method for all disease that are associated with a  modification of the plasma proteins like globulin, albumin and fibrinogen.  ESR is not a very reliable screening method as it can be raised when there is no disease and can be normal when disease is present.  It also does not indicate the type of disease.

Specimen:
  • 2 ml fresh Venous Blood or

  • 2 ml fresh EDTA Blood  (If kept at 4C not older than 24 h)

Equipment Requirements:

  • Westergren rack

  • Westergren tubes, internal diametre 2.5mm

  • Dilution bottles to hold 2 ml (4 volumes of blood/1 volume of anticoagulant diluent solution)

  • Timer (1hour)

Reagents & Stain Requirements:

  • 3.8% Trisodium Citrate Solution

Preparation of 3.8% Tri-sodium Citrate Solution 

  • Tri-sodium Citrate, anhydrous .........................................         3.8   g

  • Distilled water........................................................       up to    100 ml

Important:      Keep the solution in the refrigerator.  If the solution is cloudy or contains particle discard and prepare a fresh solution!

 

Test Procedure Instructions:

  • Measure exactly 0.4 ml of the 3.8% Tri-sodium citrate solution, with the help of a pipette or a syringe into a clean and dry small bottle.

  • Draw 2ml of venous blood and immediately place 1.6 ml  into the Trisodium citrate solution.  Note: You can also use EDTA blood.  If kept at 4C, it can be used after up to 24 hours.  In this case mix the EDTA blood well, and place 1.6 ml into the Tri-sodium citrate solution.

  • Mix the blood  and  Trisodium citrate solution well.

  • Fill a clean and dry Westergren ESR Tube with the mixture up to the 0 mark.

  • Do not mouth pipette.  Use a pipetting device.

  • Wipe the outside of the Westergren tube with a tissue.

  •  Make sure no air bubbles enter the tube. 

  • Recheck that the tube is filled up to the 0 mark, exactly.

  • Close the top of the tube firmly while you place the tube into the tube holder, otherwise the mixture could escape the tube.

  • Immediately set your timer for 1 hour or write down the time on a sheet of paper.

  • Exactly after 1 hour read how far the red cell layer has fallen. Give the result in mm per hour.

Reporting and Interpretation of Results:

Normal Value:     Male:                1 - 10 mm /hour                 Female:            3 - 14 mm /hour

Increased Values of ESR:

Are found with all diseases associated with a modification of the plasma proteins like globulin, albumin and fibrinogen.  ESR shows especially high values in:

  • Tuberculosis

  • Leishmaniases

  • Malignant condition

  • Hepatic Amoebiasis

  • Acute and Chronic Inflammation

Special Note: (While reading the result you should also pay attention to the following:)

The colour of the plasma:

  •  Dark yellow , indicates Hepatitis

  •  Clear as water, indicates lack of iron

  •  White and turbid, indicates Nephrosis, Diabetes, Lipaemia.

The layer of white blood cells just above the red cells:

  •  If increased, indicates Leukaemia. 

Internal Quality Control Procedures and Sources of Error:

  • Correct dilution of blood and Tri-sodium Citrate Solution

  • Store Tri-sodium Citrate Solution in the refrigerator

  • Tri-sodium Citrate Solution should not be turbid

  • Avoid air-bubbles in the Westergren tube

  •  Place the Westergren tube in a vertical position

  • Temperatures above 23 C increase the speed of the ESR, therefore keep the ESR rack at the coolest place of the lab and out of direct sun light.

Reference:

  • Maurice King, 1973 A Medical Laboratory for Developing Countries, London, Oxford University Press

  • WHO, 1980, Manual of Basic Techniques for a Health Laboratory. Geneva, WHO

Top

The Public Health Care Laboratory - 2001 Gabriele Mallapaty