preanalytical

Preanalytical refers to the phase of clinical laboratory testing that occurs before the actual analysis of a specimen. It covers patient preparation, specimen collection, labeling, transport, handling, processing, and storage, and it begins when the test is ordered or when the patient presents for collection and ends when the specimen is ready for analysis.

The accuracy and reliability of laboratory results depend heavily on this phase. Preanalytical factors can alter analyte concentrations and stability, leading to false positives or negatives, delays, or specimen rejection. Because most diagnostic errors arise before analysis, attention to preanalytical quality is central to patient safety and efficient care.

Common preanalytical variables include patient-related factors such as recent meals, fasting status, posture, and circadian rhythms; collection-related factors such as specimen type and tube additives; improper labeling and patient misidentification; sample quality issues such as hemolysis, lipemia, icterus; trauma during collection; delays in transport; temperature fluctuations; inappropriate storage; and processing errors such as incorrect time to centrifugation or improper centrifugation.

Quality assurance in the preanalytical phase relies on standardized procedures, staff training, proper equipment, specimen tracking, and rejection criteria. Guidelines from standards organizations such as CLSI and ISO 15189, as well as laboratory information systems and barcode-based labeling, support consistency. Error reduction strategies include standardized order of draw, correct tube selection, immediate specimen labeling, timely transport, and monitoring of preanalytical indicators.

Effective management of preanalytical processes improves diagnostic accuracy and reduces unnecessary testing.