preanalytic

Preanalytic refers to all activities that occur before the laboratory analysis of a specimen. It encompasses patient preparation, specimen collection, handling, transport, storage, and processing. The preanalytic phase is distinct from the analytic phase, which covers the actual measurement, and the postanalytic phase, which includes result reporting and interpretation. Because many errors arise before testing, the preanalytic stage is a major focus of quality control efforts.

Key elements include proper patient identification, correct test ordering, appropriate fasting status or timing, and selection of suitable collection methods and containers. The order of draw, use of additives, and tubes' fill volumes influence test outcomes, particularly for chemistry and coagulation assays. Specimen integrity is sensitive to delays, temperature changes, and mechanical stress; common issues include hemolysis, lipemia, icterus, clotting, and specimen mislabeling.

Handling and transport practices are designed to preserve analyte stability, including timely transport, appropriate temperature control, and proper specimen separation when required. Processing steps, such as centrifugation and aliquoting, must be performed consistently to minimize variation.

Quality assurance in the preanalytic phase relies on standard operating procedures, staff training, barcoding and labeling accuracy, correct patient and specimen identification, and monitoring of turnaround times. Improvements in preanalytic processes can significantly reduce erroneous results and improve laboratory reliability and patient safety.