SPECIAL COLLECTIONS AND POINT OF CARE TESTING

• Pre-analytical Errors


  46-68% of all errors for laboratory samples
• Improper patient identification


  • Most serious, potentially most dangerous preanalytical error
• Routine handling


  • Mixing, transport at RT
• Special handling


  • Body temp., chilled, light-sensitive specimen
• Processing


  Centrifugation, aliquot preparation
• Physiological variables that may affect laboratory results

  • Age
  • Altitude
  • Position
  • Dehydration
  • Pregnancy
  • Diet
  • Smoking
  • Stress
  • Temperature
  • Drug therapy
  • Exercise
  • Fever
  • Gender
  • Diurnal or Circadian variations
• Possible Sources of Preanalytical Error (at time of collection)


  • Misidentified patient
  • Antiseptic not dry
  • Expired tube
  • Wrong collection time
  • Incorrect needle position
  • Incorrect needle size
  • Mislabeled tube
  • Nonsterile site preparation
  • Incorrect collection tube
• EDTA


  Prevents the aggregation of platelets and preserves the morphology of cells so it can be counted accurately
• Sodium fluoride


  Prevents glycolysis
• Inverting red tube can cause hemolysis
• EDTA interfere with electrolytes
• Correct order of draw

  • Sterile blood culture tubes - Yellow
  • Coagulation tubes - Light blue
  • Serum tube/ Plain tube - Red
  • Heparin tube - Green
  • EDTA tube - Lavender/Purple
  • Anti-glycolytic tube/ Fluoride - Gray

  
• Issues with underfilled tube

  • Dilutional effect
  • Blood clots
  • Citrate tubes for coagulation studies most critical
  • Blood to anticoagulant ratio: 9:1
  • Partially filled tube: collect again
  • Do not combine 2 partially filled tubes
• Hemoconcentration


  Changing from supine to standing, fluid leaks from the vessel to the tissue
• Hemodilution


  Remaining supine for a long time, fluid from the tissue goes to the vessel
• Prolonged tourniquet application


  Increases the intervascular blood pressure, small molecules are pushed from the blood vessels to the surrounding tissue
• Ideal tourniquet application time is not more than 1 minute, 3-4 inches above the site
• Prolonged tourniquet application causes hemoconcentration
• Labeling Specimens


  1. Immediately after collection

  2. Before dismissing an outpatient

  3. Before leaving the room of an inpatient

  4. Reverification of patient information before labeling

  5. Show the labeled tube to the patient or have the patient initial or sign a document stating that they were shown the labeled tube and confirmed that the information was correct
• Regular Vacutainer Label Placement

  • Patient's name must be read from left to right
  • Label to cover the manufacturer's label leaving a gap from the top of the label to the colored cap
• Microtainer Label Placement


  • Patient's name from left to right
  • Label directly underneath the colored top
  • No gap between the colored top and the label
• Possible Sources of Preanalytical Error (during specimen transport)

  • Agitation-induced hemolysis
  • Delay in transporting
  • Exposure to light
  • Failure to follow temperature requirements
  • Transport method (e.g., hand vs. pneumatic tube)

  
• Possible Sources of Preanalytical Error (during specimen processing)

  • Contamination (e.g., dust or glove powder)
  • Delay in processing or testing
  • Delay in fluid separation from cells
  • Evaporation
  • Failure to centrifuge specimen according to test requirements
  • Failure to separate fluid from cells
  • Incomplete centrifugation
  • Mislabeled aliquot
  • Multiple centrifugations
  • Rimming of clots

  
• Possible Sources of Preanalytical Error (during specimen storage)

  • Exposure to light
  • Temperature change outside defined limits
• Mixing of tubes by inversion

  3 to 10 gentle inversions (depends on the type of tube and additive) for additive tubes to ensure even distribution of additive and minimize hemolysis
• Vigorous mixing can cause hemolysis
• Mixing is not performed on hemolyzed specimens for potassium, magnesium, and most enzyme tests
• Inadequate mixing of anticoagulated tubes

  Can cause micro clot formation and erroneous test results, especially for hematology studies
• Inadequate mixing of gel separation tubes

  Can cause incomplete clotting
• Non-additive tubes should not be mixed
• Proper mixing of EDTA or other additives is important to prevent blood clotting which may affect the results
• Transporting specimens


  • Rough handling and agitation can hemolyze specimens, activate platelets and affect coagulation tests, and break glass tubes
• Tubes should be transported stopper up to reduce agitation, aid clot formation in serum tubes, and prevent contact of the contents with the stopper
• Primary container


  • Self-sealing plastic bag with 2 compartments (1. sample, 2. requisition form), wrapped in absorbent package material, with biohazard logo
• Transport bag


  • Liquid-tight closure plastic bags with slip pocket for paperwork (requisition form), with visible biohazard logo
• Multiple samples from one patient can be placed in one bag, but samples from different patients should not be placed in the same plastic bag
• Large number of samples should be placed in a rack, and the rack placed in a bag or leak-proof box
• Pneumatic tube transport (PTT)


  System that propels cylindrical containers through networks of tubes by compressed air or by partial vacuum, more traumatic but faster delivery
• Pneumatic tube specimens should be protected from shock and sealed in zipper-type plastic bags to contain spills
• Automated Transportation systems


  Robot specimen transportation system called the RoboCourier® Autonomous Mobile Robot