A failure to properly fill a light blue top tube for coagulation tests may introduce what type of variable to the test system?

Question

Quizplus · Accepted Answer

A light blue top tube is used for coagulation tests because it contains sodium citrate, which acts as an anticoagulant by binding to calcium ions in the blood. If the tube is not properly filled, the ratio of blood to anticoagulant may be altered, leading to incorrect test results. This type of error occurs prior to the actual examination of the sample, and is therefore considered a preexamination variable.

A Failure to Properly Fill a Light Blue Top Tube