Hematology is the branch of medicine concerned with the study, diagnosis, treatment, and prevention of diseases related to blood. When it comes to infections, cancers and autoimmune diseases, Erythrocyte Sedimentation Rate (ESR) plays a key role. This relatively simple, inexpensive, non-specific test has been used to detect inflammation and various other conditions associated with it. An ESR is typically conducted along with various other tests as this does not allow the health practitioner to identify where the inflammation is in the body. Also an ESR can be affected by several other conditions besides inflammation.