6 Specimen Handling and Processing

Protecting specimen integrity

Specimen integrity depends on correct identification, timely transport, and processing that follows the test’s requirements. Required specimen type, tube, processing time, temperature, and storage conditions can differ by test, so follow the laboratory’s current procedure and the test’s collection instructions.

Labeling and initial checks

Label each primary collection tube with the required patient identifiers and specimen information according to facility policy. In routine practice, use at least two approved patient identifiers; include the collection date and time when required. Label the tube itself, not only its cap, and make sure the information is legible and matches the order or requisition.

Complete labeling at the collection site according to policy. Never guess at an identity or silently correct an uncertain label. Resolve discrepancies before processing and follow the laboratory’s acceptance and rejection procedures.

Before sending the specimen, check that the correct tube was collected, that it is adequately filled when fill volume matters, that the cap is secure, and that the outside is clean. Note collection or handling issues when policy requires it. A visibly leaking or misidentified specimen may be unsuitable; notify the laboratory and recollect when directed rather than attempting an unauthorized fix.

Handling and transport

Treat all blood specimens as potentially infectious. Wear appropriate personal protective equipment, handle tubes gently, and keep them closed except when processing requires opening. Place tubes in a secure, leak-resistant secondary transport container capable of containing a spill. Keep paperwork or requisitions separate from the specimen compartment.

Use the transport method and any temperature control specified by the laboratory. Transport promptly to reduce delays and avoid conditions that can alter results. Use pneumatic-tube transport only when it is approved for the specimen and the system.

Do not assume that every specimen should be chilled, frozen, or kept at room temperature. Requirements depend on the analyte and specimen type. A specimen intended for whole-blood testing may have different handling needs from serum or plasma. Check the test directory or laboratory instructions when requirements are uncertain.

Centrifugation

Centrifugation separates components by density. After anticoagulated blood is centrifuged, plasma is generally the upper layer, with a thin buffy coat of white cells and platelets above the red cells. In a clotted specimen, serum separates from the clot and cells. Allow serum tubes to clot as directed before centrifugation; mix anticoagulated tubes as instructed and process them according to their procedure.

Use the specified centrifuge, tube, relative centrifugal force (RCF), time, and temperature. RCF ($\times g$) describes the force applied to the sample. Revolutions per minute (RPM) describes rotor speed and does not represent the same force across different centrifuges. Do not substitute settings or extend processing time unless the procedure permits it.

Balance opposing tubes according to the laboratory’s procedure, secure the lid, and use sealed safety cups or rotors when required. If breakage is suspected, do not open the centrifuge immediately; follow the equipment and spill-response procedure.

Aliquoting and storage

An aliquot is a measured portion transferred from the original specimen into a separate container. Use a clean, appropriate transfer device and a properly identified secondary tube or vial. Label the receiving container before or during transfer according to policy, preserving patient identifiers and adding the specimen type and any other required details.

Avoid touching the pipette to unrelated surfaces, disturbing the cell layer, or transferring cells or clot when the test requires separated serum or plasma. Close the aliquot securely.

Store the primary specimen and aliquots under the conditions and for the duration specified for the test. If freezing is required, use a freezer-compatible container and follow instructions for preventing repeated freeze–thaw cycles. Document processing or storage details when required. When sending a specimen to another laboratory, use the applicable transport procedure and temperature controls.

Putting the steps together

Accurate labeling links the specimen to the correct patient and order. Secure, prompt, temperature-appropriate transport helps preserve the specimen. Centrifuge only under specified conditions, use safe equipment practices, and transfer separated material into correctly labeled aliquot containers. Because processing and storage requirements vary by test, the laboratory’s current instructions take precedence over general rules.