How to Answer: Why is a discard tube necessary when drawing a light blue top?
Advice and answer examples written specifically for a Phlebotomist job interview.
24. Why is a discard tube necessary when drawing a light blue top?
How to Answer
Understanding the order of the draw and why a discard tube is necessary is crucial to performing a phlebotomist's job. Explain your understanding of the necessity of a discard tube to the interviewer.
Written by Heather Douglass on June 7th, 2021
Entry Level
"A light blue top tube has to have a certain amount of blood in it for the test to be accurate. Using a discard tube helps to rid the tubing of any air in the tubing attached to the needle. Air could prevent the blue tube from being accurate."
Written by Darby Faubion
Answer Example
"Using a discard tube helps to empty any air of the butterfly tubing, which allows the light blue top to be filled with the appropriate amount of blood."
Written by Heather Douglass on June 7th, 2021
Experienced
"A light-blue top tube that will be used for coagulation testing must be filled to completion. Under-filling the tube changes the ratio of blood to anticoagulant. This can affect the accuracy of coagulation tests that are performed using this specimen. If a winged blood collection device (butterfly) is used to collect a light-blue top tube for coagulation studies, a waste tube should be drawn first. If the air is not displaced from the tubing into a waste tube, it will be drawn into the tube used for testing and cause a short-fill of the tube. Less volume of blood in the tube alters the required blood to anticoagulant ratio needed for coagulation studies."
Written by Heather Douglass on June 7th, 2021