Specimen Quality, Rejection and Recollection

The Phases of Testing and Preanalytical Control

Laboratory testing follows a continuous path that is divided into three distinct phases: preanalytical, analytical, and postanalytical. The preanalytical phase begins the moment a healthcare provider orders a test and ends when the actual sample testing begins. The analytical phase consists of performing laboratory tests, whether by instrument or manual method. Finally, the postanalytical phase involves the verification, reporting, and archiving of laboratory test results. The phlebotomist plays a foundational role in this cycle because the majority of all laboratory testing errors occur during the preanalytical phase.

Phlebotomists directly control preanalytical variables within their scope of duties. These essential responsibilities include patient identification, specimen collection, labeling, handling, and transport. Everyday technical choices make a substantial difference in test outcomes. For example, common preanalytical errors include patient misidentification, incorrect tube selection, and improper specimen mixing. Using an incorrect order of draw can cause additive carryover between tubes and compromise subsequent test results.

A specimen's journey after it leaves the patient's arm is just as critical as the collection itself. Delayed specimen transport and improper storage temperatures are preanalytical errors that compromise specimen integrity. Technical errors during venipuncture also alter sample composition before the needle is even withdrawn. For instance, prolonged tourniquet application exceeding one minute causes hemoconcentration, which is an entirely avoidable preanalytical error that distorts blood components. Maintaining strict adherence to standard collection and handling steps preserves sample quality from order entry to processing.