The erythrocyte sedimentation rate, also known as ESR, sedimentation rate or Westergren sedimentation rate, is a nonspecific, simple and inexpensive test to detect inflammation, according to the American Association for Clinical Chemistry. The test is performed by drawing blood and measuring the sedimentation rate of red blood cells.
Inflammation detected by the test is often linked to infectious diseases, cancers and autoimmune diseases. While the test helps find the general presence of inflammation, the test does not indicate the cause or specific location of the inflammation. In addition, the ESR test is affected by factors other than inflammation, so other tests are typically performed in conjunction with an ESR, according to the American Association for Clinical Chemistry.