Specimen Handling, Processing, and Point-of-Care Testing
What you must understand
Most errors that reach the analyzer are pre-analytical. Know the inversion counts after collection - gentle 180-degree mixing, never shaking: light blue 3–4 times, serum tubes about 5, lavender EDTA 8–10, green and gray 8–10. Labeling happens first, then mixing; the tube is never left unstoppered.
Know transport conditions. Most serum and plasma specimens are transported promptly and may be refrigerated, but blood cultures are never refrigerated, blood gas and lactate specimens go on ice, and specimens for bilirubin or other light-sensitive analytes are wrapped in foil. Chilling can alter some analytes and cause cold agglutination, so follow the test-specific requirement rather than a blanket rule.
Processing: allow serum tubes to clot fully before centrifugation; plasma tubes are centrifuged per protocol; gel separator tubes keep serum or plasma above the barrier. Aliquot when required. Recognize rejection triggers: unlabeled or mislabeled tubes, wrong tube for the test, clotted anticoagulated samples, gross hemolysis, insufficient volume, and expired tubes. Document any specimen collected under unusual circumstances (for example, drawn above an IV) so the laboratory can interpret the result.
Point-of-care testing adds operator responsibility: verify identity, check strip/cartridge and control solution expiration and lot numbers, run and document controls, follow the manufacturer's instruction on whether the first drop is used, record the result, time, and operator, and escalate critical values per policy.
Traps
- "Refrigerate all specimens" - false for cultures and several specialized analytes.
- Shaking instead of inverting.
- Reporting a glucose result without confirming quality control is current.
Rule of thumb: label, invert, and read the test's transport note - when in doubt, contact the laboratory rather than guessing.