Standard Operating Procedure: Hematology Laboratory Operations

This Standard Operating Procedure (SOP) outlines the mandatory protocols for the daily operation of the Hematology Laboratory. Adherence to these guidelines is critical to ensure patient safety, analytical accuracy, and compliance with clinical laboratory accreditation standards (e.g., CAP, CLIA, or ISO 15189). This document covers the complete workflow from sample receipt and instrument verification to quality control and final result authorization.

1. Pre-Analytical Phase: Sample Receipt and Processing

• Verify Patient Identification: Ensure every specimen container is labeled with at least two unique patient identifiers (e.g., full name and DOB/MRN) matching the electronic order.
• Sample Integrity Check: Inspect the specimen for hemolysis, icterus, lipemia, or the presence of micro-clots.
• Tube Requirements: Confirm the use of lavender-top (K2 or K3 EDTA) tubes. Reject any samples that are clotted, improperly filled (incorrect blood-to-anticoagulant ratio), or received in the wrong additive.
• Log-in: Enter the sample into the Laboratory Information System (LIS) immediately upon receipt to establish the audit trail.

2. Analytical Phase: Instrument Maintenance and Calibration

• Daily Startup: Perform the automated startup cycle as specified by the hematology analyzer manufacturer.
• Background Count: Run a background check on diluents and cleaning reagents to ensure they are free of particulates.
• Quality Control (QC): Run tri-level (low, normal, high) QC material. Ensure all results fall within the established ±2 SD range. Do not proceed with patient samples if QC fails.
• Calibration Verification: Review the calibration status of the analyzer; ensure calibration is within the valid timeframe or immediately following significant hardware interventions.

3. Analysis and Manual Review

• Sample Processing: Load samples onto the automated track or rack; ensure barcodes are correctly positioned for scanning.
• Flag Review: For all "flagged" results (e.g., blast alerts, abnormal RBC indices, platelet clumps), perform a peripheral blood smear.
• Smear Preparation: Prepare a wedge smear on a clean glass slide, air dry, and stain using an automated Wright-Giemsa stainer.
• Microscopic Examination: Perform a 100-cell manual differential if automated counts trigger specific alert thresholds.

4. Post-Analytical Phase: Reporting and Archiving

• Data Validation: Review results for clinical plausibility (e.g., rule of three for Hemoglobin/Hematocrit).
• Critical Value Reporting: Immediately notify the ordering physician or designated nursing staff of all critical values (e.g., extreme leukocytosis, severe anemia, or thrombocytopenia) as per the facility's critical notification policy.
• Result Authorization: Digitally sign off on all results in the LIS once verified.
• Specimen Storage: Store processed EDTA tubes at 2–8°C for the mandated retention period (typically 48–72 hours) before biohazard disposal.

Pro Tips & Pitfalls

• The "Clot" Trap: Always invert EDTA tubes gently 8-10 times immediately after collection to prevent microscopic clots. If a machine flags "platelet clumping," always request a new sample drawn in a blue-top (sodium citrate) tube to verify if it is an EDTA-dependent pseudothrombocytopenia.
• Maintain Your Reagents: Monitor reagent expiration dates and lot numbers diligently. Changing a lot number without updating the LIS or running a lot-to-lot correlation study is a major audit finding.
• Preventive Maintenance: Do not wait for an error message to perform maintenance. Adhere strictly to the manufacturer’s weekly and monthly maintenance schedules to prevent downtime.
• Ergonomics: When performing manual differentials, ensure your microscope is at the correct height to prevent repetitive strain injury.

Frequently Asked Questions (FAQ)

Q: What should I do if a patient’s QC result is outside the acceptable range? A: Stop all testing on that instrument immediately. Check the expiration of the QC material, ensure the instrument is clean, and re-run the control. If it fails again, open a new vial of control. If failure persists, troubleshoot the reagent status or hardware and document all actions taken.

Q: How do I handle a sample that is flagged for "platelet clumps"? A: Verify the presence of clumps by making a peripheral smear. If clumps are confirmed, call the nursing station to request a redraw. If the patient has a history of EDTA-induced pseudothrombocytopenia, perform the count using a sodium citrate tube and apply a correction factor (usually multiplying the result by 1.1).

Q: Are there specific cleaning protocols for the hematology analyzer? A: Yes. In addition to daily automated cleans, perform a deep-clean cycle (or "bleach" cycle) weekly to prevent the build-up of protein and cellular debris in the flow cell or apertures, which is the most common cause of spurious flagging.