Before we explore the significance of the rubber stopper, let's briefly examine the anatomy of a blood collection tube. Blood collection tubes, also known as blood collection containers or vacutainers, are essential tools for collecting and preserving blood samples. These tubes consist of several components, including the tube itself, an anticoagulant or clot activator, and a rubber stopper.
Sealing and Preservation: The primary function of the medical rubber stopper is to create an airtight seal within the blood collection tube. This seal is crucial for preserving the integrity of the blood sample. It prevents contamination, evaporation, and the loss of sample quality during storage and transportation.

Blood-Material Compatibility: Medical rubber stoppers are designed to be compatible with blood components, ensuring that they do not interact with or leach harmful substances into the blood sample. This compatibility is essential for accurate test results.

Closure and Inversion: Medical rubber stoppers facilitate the closure of the blood collection tube after the sample is collected. They also allow for safe tube inversion to mix the anticoagulant or clot activator with the blood, depending on the required test. This ensures that the sample remains viable for laboratory analysis.