Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam 2026 - Free Medical Laboratory Science Practice Questions and Study Guide

The anticoagulant found in a green stoppered vacutainer is heparin. Heparin is a fast-acting anticoagulant that works by inhibiting the action of thrombin and factor Xa, thereby preventing the conversion of fibrinogen to fibrin. This property makes it particularly useful for tests requiring immediate anticoagulation, as it allows for the rapid collection of blood samples without the risk of clot formation.

The color of the stopper in vacutainers is standardized; green stoppers indicate the presence of heparin, commonly used in clinical laboratories for various tests, including those related to plasma chemistry and blood gas analysis. Understanding these color codes is crucial for laboratory personnel to ensure the appropriate collection and handling of blood samples.