Erythrocyte Sedimentation Rate (ESR) test is also called sedimentation rate test or sed rate test. It is used to determine if the patient is experiencing any inflammation. The test alone does not indicate the cause of the inflammation or the part of the body that is inflamed. It merely points to the existence of inflammation. The patient's blood is placed in a tall, thin tube and time that it takes to reach the bottom of the tube is measured. Inflammation can causes the appearance of abnormal proteins in the blood which cause the red blood cells to clump making them fall quickly.