• Preparation: • Confirm tube sterility and expiration. • Select correct citrate concentration (commonly 3.8%).
• Collection Procedure: • Collect blood using a sterile technique. • Fill to the marked line to maintain the 4:1 blood-to-additive ratio. • Gently invert the tube 8–10 times to mix properly.
• Testing: • Let the sample stand vertically for 1 hour in an ESR stand. • Measure the height of the clear plasma above the sedimented RBCs
• Precautions: • Underfilling or overfilling may lead to inaccurate results. • Use immediately after collection or within 2 hours for optimal accuracy. • Store at room temperature (2–25°C) and avoid freezing.
• Disposal: • Dispose of used tubes in accordance with biohazard waste protocols.

Note: Overfilling or underfilling may affect test accuracy.