An ESR tube rack is a specialized laboratory accessory designed to hold blood collection tubes securely and vertically during the Erythrocyte Sedimentation Rate (ESR) test. This test, a common hematology procedure, measures how quickly red blood cells settle in a tube over one hour, helping clinicians detect inflammation, infections, or autoimmune disorders.
The rack's primary function is to maintain absolute tube verticality. Even a slight tilt of 1–3 degrees can significantly accelerate sedimentation, producing false results. To ensure this, ESR racks are built with a weighted, stable base and precisely aligned slots that grip tubes or Westergren pipettes firmly.
These racks are typically made from durable materials such as acrylic, polycarbonate, or ABS plastic, which are chemically resistant to cleaning agents and blood samples. Many designs feature a transparent body, allowing easy visual monitoring of sedimentation levels without removing the tubes. Depending on the lab's workflow, racks may hold 10, 20, or 50 tubes, often in two rows to accommodate duplicates or controls.
Modern ESR racks also prioritize safety and ergonomics. They may include biosafety covers to prevent aerosol exposure, color-coded inserts for easy identification of sample types, and non-slip feet to prevent accidental tipping. Some advanced models are compatible with automated ESR analyzers, allowing the rack to be placed directly into the reading instrument.