Erythrocyte sedimentation rate

The erythrocyte sedimentation rate (ESR), also called a sedimentation rate or sed rate, is a non-specific measure of inflammation that is commonly used as a medical screening test.

A rack of ESR tubes.
To perform the test, anticoagulated blood is placed in an upright tube and the rate at which the red blood cells fall is measured and reported in mm/h. When an inflammatory process is present, the high proportion of fibrinogen in the blood causes red blood cells to stick to each other. The red cells form stacks called rouleaux which settle faster.
The ESR is increased by any cause or focus of inflammation. The basal ESR is slightly higher in females.