Which of the following practices can help prevent specimen contamination?

Using sterile equipment and proper aseptic techniques is vital in preventing specimen contamination because it minimizes the risk of introducing pathogens or foreign materials into the specimen. Aseptic techniques involve practices that maintain sterility throughout the specimen collection process, such as washing hands, wearing gloves, and using disinfectants. By ensuring that all instruments and containers are sterile and that the collection environment is controlled, the integrity of the specimen can be preserved, which is crucial for accurate testing results.

Other practices listed, such as reusing needles and syringes, leaving specimen containers open, or collecting specimens in high-traffic areas, significantly increase the risk of contamination and compromise the validity of the specimen.