LESSON 4 PREANALYSIS

• Up to 70% also lab diagnostic errors occur in the Pre-analysis phase or the Preanalytical phase
• We need to be very careful in performing Phlebotomy and inpatient identification because it is one of the few mistakes that we encounter in the Pre-analysis phase (improper patient identification, wrong tube labeling
• 32-75% of testing errors happens in the Pre-Analysis Phase
• Errors = extra work; diagnostic delayed; extra cost
• IN VIVO


  tobacco smoking, alcohol & drug ingestion
• Reasons for hemolysis

  needle too small, pulling plunger too fast, transferring blood too vigorously

  shaking tubes vigorously

  collecting blood before alcohol dried
• Verbal requests are made only in emergency situations and should be documented on a standard form
• ★ Patient Demographics - Patient’s name, Age/Sex - Date of Birth (DOB), Date of Admission (for inpatients), Date of Test Order, Location, Attending Physician
• MISIDENTIFICATION is a __ for medtechs
• Which test requires the presence of a witness

  Drug test
• Reasons for Specimen Rejection: 1. Hemolysis/Lipemia 2. Clot present in an anticoagulated specimen 3. Nonfasting specimen when test requires fasting 4. Improper blood collection tube 5. Short draws, wrong volume 6. Improper transport conditions (ice for blood gases) 7. Discrepancies between requisition and specimen label 8. Unlabeled or mislabeled specimen 9. Contaminated specimen/Leaking container
• Most hospitals do Labeling on the tubes and stick the barcode
• Problematic Sites -

  Burns, scars, tattoos - Damaged veins - Sclerosed - Thrombosed - Edema - Hematoma - Mastectomy - IV sites - Fistula
• Next most common specimen, Usually requires a timed specimen and/or complete collection

  URINE
• Creatinine is often used to assess completeness of a collection
• 24 hour urine specimens; 12 hour urine specimens
• The urine in the laboratory is processed 30 minutes to an hour
• False-negative ketone

  Volatilization of acetone; breakdown of acetoacetate by bacteria
• arterial blood glass - it needs to be transported with ice
• Specimen must always be transported carefully to prevent breakage and protect specimen integrity
• lipid panels, we usually ask for 10-12 hours of fasting
• Before Collection 1. Incorrect test ordered 2. Inadequate patient preparation (e.g., not fasting, recent heavy meal–lipemia) or improper timing (e.g., through drug level drawn too early) 3. Misidentification of patient
• During Collection 1. Wrong container/wrong additive 2. Short draws/wrong anticoagulant/blood ratio 3. Hemoconcentration from prolonged tourniquet time (less than 1 minute) 4. Hemolysis due to incorrect technique (e.g., forcing blood through needle, draw via intravenous line)
• After Collection 1. Inadequate mixing/clots 2. Mislabeling of specimen 3. Improper transport to lab: Exposure to light/extreme temperature or delayed delivery 4. Processing errors: incomplete centrifugation, incorrect log-in, improper storage, or aliquoting prior to analysis.