1.2.5 Anatomy, Physiology, and Health Education I Laboratory
Lab 3 Determination of Erythrocyte Sedimentation Rate by Westergren's Method (Cont'd...)
vii. The Laboratory factors which influence ESR are as follows:
a. Time: The test should be performed as early as possible after the collection of fasting specimen. There is progressive decrease in sedimentation in first four hours and after that there is a rapid decrease in sedimentation.
b. The length of the ESR tube: ESR is greater with longer tubes (Westergren's tube) than with shorter tube (Wintrobe's tube). To ensure reliable results the column of blood should be as high as possible. The internal diameter of the tube should be more than 2.5 mm. The tubes should be kept in vertical position. Deviation of the tubes from the vertical position increases the ESR.
c. Temperature: The red cell sedimentation is increased at higher temperature.
Westergren's ESR lube, stand for holding the tube, timer or watch.
1. Fill the Westergren's tube exactly up to zero mark by means of a rubber bulb (avoid air bubbles).
2. Place the tube upright in the stand. It should fit evenly into the groove of the stand.
3. Note the time. Allow the tube to stand for exactly one hour.
4. Exactly after one hour, note the level to which the red cell column has fallen.
5. Report the result in terms of mm/after 1st hour.
The ESR of the given sample is ........... mm in 1st hour.
After the experiment, wash the tubes carefully under running tap water. Also rinse them in de-ionized water and dry to an incubator between 40degC-50degC.
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