Frequently Asked Questions
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I have read some old papers indicating that the 1 hour
reading time of the ESR can be greatly reduced by fixing the tube at an
angle of 60 or 45 degrees instead of upright. Does this give accurate
results?
No, the ESR tube (DispetteTM) must always be
perfectly vertical as measured by a spirit bubble or plumb line. The
papers in favour of the idea written in the mid 1930's and early 1940's
were shown to be faulty by several workers and finally discredited in
1967 (Lemtis and Schoetensack). The ICSH continues to recommend that the
tube "should be held vertical (confirmed by a plumb line or equally
effective device)"
Can I use EDTA anticoagulated blood to perform the ESR test?
Yes, but if you are performing the Westergren method test as do most
people today, you still need to make the one in five dilution (i.e. four
parts blood added to one part diluent) that was used with the original
technique because only liquid citrate was available at that time as an
anticoagulant. The diluent you use can be normal saline or trisodium
citrate at a concentration of between 0.10 to 0.136 mol/litre. - see
ICSH. recommendations, Journal of Clinical Pathology, 1993; 46:
198 - 203.
When filling the Dispette 2 system, if the blood reaches the
zero mark at the top before the other end of the Dispette gets to the
bottom of the filling reservoir should I stop pushing and just set up
the test in the stand as it is?
No, otherwise the red cells will fall into the space
between the bottom of the Dispette and the filling reservior and hence
give inaccurate results. The overflow chamber above the zero mark on the
Dispette is designed to take the excess blood that will result from
pushing right to the bottom.
Can the micro method give the same accuracy as the full
Westergren method?
No, although some workers have shown good correlation between the two
methods in ESRs giving normal to slightly raised values ( Barrett BA,
Hill PI. J Clin Path, 1980; 33: 1118 - 1120).
But the higher the ESR the greater is likely to be the variation between
the results given by the two methods. Never-the-less this means that the
Micro-Dispette can be a very useful screening method or an indicator of
normal or raised ESR values where it is difficult to obtain a larger
volume of blood sample.
Do Guest ESR systems conform to NCCLS Standards?
Yes, those pipettes marked 'Westergren' on the tube (i.e DispetteTM,
Dispette 2TM, and VacupetteTM) are designed to meet the
specifications set by the International Congress for Standardisation in
Haematology, published in 1993. The NCCLS standards were revised to
conform to the ICSH Standards later that same year The citrated blood
collection bottles and five-place ESR stand are also designed to meet
ICSH recommendations.
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