Welcome innovation in erythrocyte sedimentation testing.

The erythrocyte sedimentation rate (ESR) test is a laboratory test that serves as a “sickness index” in conjunction with the patient’s clinical history and physical examination findings. Therefore, it has been a popular procedure for many years, since it is useful to have this information available to the physician within minutes after seeing the patient to decide on appropriate steps for care of the patient. A Swedish physician, Fahraeus, first conceived of the ESR test in 1921. 1 Since then, a variety of methods have been developed that have improved the procedure. In recent years, a great number of technical innovations have made the testing less hazardous and more easily performed by laboratory personnel. 2 A cursory glance at the College of American Pathologists’ (CAP) ESR survey summary reports reveals many different sedimentation tubes. In some cases, the laboratories use whole blood, and others dilute the specimen. With this proliferation of methods, there is increased variation in the reported results and an inherent difficulty in interpretation of these results. 3 There was an evident need for a reliable reference method against which the newly developed equipment and instruments could be evaluated. The International Committee for Standards in Haematology 4 and the National Committee for Clinical Laboratory Standards (NCCLS) 5 recommend comparison methods and procedures to improve the precision and accuracy and lower the biohazards associated with this test. The use of disposable sedimentation rate tubes of acceptable internal diameter is one such recommendation. Also specimens with hematocrit values more than 35% (0.35) are known to yield less precise results, and, therefore, only specimens with hematocrit values less than 35% (0.35) are acceptable for comparative purposes. Likewise, sedimentation tubes with internal diameters of less than 2.55 mm can produce variable results. Therefore, the recommended referral methods incorporate this information into their criteria. These standardization groups have published recommendations for a hierarchy of methods against which new methods could be compared. 4,5  The reference method uses a 200-mm, open-ended Westergren pipette with an internal diameter of 2.55 mm or more filled with undiluted blood having a packed cell volume (hematocrit) of 35% (0.35) or less that has been collected in EDTA anticoagulant.  The standardized method uses a 200-mm, open-ended