CPT (Certified Phlebotomy Technician) Practice Exam

Which vial gets filled first when doing a blood culture?

1. Light blue

2. Light green

3. Light yellow

4. Light pink

The correct answer is: Light yellow

When performing blood cultures, the light yellow vial is typically used for this purpose because it often contains a nutrient broth that supports the growth of microorganisms. Blood cultures are crucial for identifying infections, particularly those caused by bacteria or fungi. By collecting the blood sample in a light yellow vial, the technician ensures that the sample is placed in an appropriate medium for incubation and subsequent analysis. The order of drawing blood specimens is essential to avoid contamination and ensure the validity of test results. While other vials serve different purposes—like the light blue for coagulation studies, the light green for certain chemistry tests, and the light pink for blood typing—the light yellow is specifically designed for cultures, making it the first vial to be filled when obtaining a sample for this type of testing. This practice helps maintain the integrity of the culture and ensures optimal conditions for growth and detection.