Erythrocyte sedimentation rate (ESR) test is a blood test that measures the rate at which erythrocytes (red blood cells) from blood samples descend and settle down a test tube. Under normal circumstances, erythrocytes take a long time to settle. However, in the presence of inflammation or cell damage, erythrocytes clump together, making them bulky, which increases their rate of settling. When erythrocytes settle rapidly, the ESR value increases.  ESR values ​​higher or lower than the normal indicate the presence of the disease. ESR is not a diagnostic test. That is, it does not help in diagnosing any particular disease. It is a simple, cost-effective and screening test that indicates the presence or absence of inflammatory diseases anywhere in the body.  In addition to the ESR, other tests should also be done to identify the exact cause of the swelling.