Lesson 9

• It has been estimated that 46% to 68% (32%-75%, McPherson et. al., 2011) of all laboratory errors occur prior to analysis
• Phases of the testing process

  • Preexamination / Preanalytical
  • Examination / Analytical
  • Postexamination / Postanalytical
• Proper handling from the time a specimen is collected until the test is performed helps ensure that results obtained on the specimen accurately reflect the status of the patient
• Red and Gold


  • 15 min to clot
  • Clot muna bago centrifuge
• Chemistry


  10 mins
• Serology


  15 mins
• Citrate


  • After transportation, centrifuge immediately
  • Plasma is the sample, send to hematology
• Aliquot


  Transfer of specimen one tube to another
• Red top


  In contact with each other (serum and RBC)
• Gold top


  May nagseseparate
• Enzymes


  • Sensitive to temperature
  • 50 degrees celcius - start to degrade enzymes
  • Hemolyzed affects enzymes
• Lactate dehydrogenase


  • Present in everywhere
  • LD1 - in liver
• Possible sources of preexamination/preanalytical error

  • Altitude
  • Dehydrated Patient
  • Duplicate Test Orders
  • Exercise
  • Inadequate fast
  • Incomplete requisition
  • Medicatons
  • Patient Stress
  • Pregnancy
  • Smoking
  • Strenuous Exercise
  • Treatments (e.g, intravenous medications, radioisotopes)
  • Wrong test ordered
• At time of collection

  • Misidentified Patient
  • Antiseptic not dry
  • Expired Tube
  • Failure to invert additive tubes properly
  • Faulty technique
  • Improper vein selection
  • Inadequate volume of blood
  • Inappropriate use of plasma separator tube (PST) or serum separator tube (SST)
  • Incorrect collection tube
  • Incorrect needle position
  • Incorrect needle size
  • Mislabeled tube
  • Mixing tube too vigorously
  • Nonsterile site preparation
  • Patient position
  • Prolonged tourniquet application
  • Underfilled Tube
  • Wrong Collection time

  
• 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)

  
• During specimen processing


  • Contamination
  • Delay in processing or testing
  • Delay in fluid separation from cells
  • Evaporation
  • Failure to centrifuge specimen according to test requirement
  • Failure to separate fluid from cells
  • Incomplete centrifugation
  • Mislabeled aliquot
  • Multiple centrifugation
  • Rimming of clots

  
• During specimen storage


  • Exposure to light
  • Temperature change outsie defined limits
• Capulat


  Seal using clay; read using hematocrit reader; count WBC and RBC
• Newbower slide


  Input microscope, count manually WBC and RBC
• Platelet


  Count manually on microscope
• • The second LDH1 is in liver the LDH2 is inside the RBC
  • If the RBC is ruptured there is false elevation of RBC
• Mixing tubes by inversion

  • Gentle inversion helps to distribute the additive evenly while minimizing the chance of hemolysis
  • Inadequate mixing of anticoagulant tubes leads to microclot formation
  • Inadequate mixing of gel separator tubes may prevent the additive from functioning properly, and clotting may be incomplete
  • Nonadditive tubes do not require mixing
• Transporting Specimens


  • Tubes should be transported stopper up to reduce agitation, aid clot formation in serum tubes, and prevent contact of the tube contents with the tube stopper
  • CLSI and OSHA guidelines require specimen transport bags to have a biohazard logo, a liquid-tight closure, and a slip pocket for paperwork
  • Nonblood specimens should be transported in leak-proof containers with adequately secured lids
  • All specimens transported through pneumatic tube systems should be protected from shock and sealed in zipper-type plastic bags to contain spills

  
• Pneumatic tube system


  Specimens sent via pneumatic tube system must be in zipper-type plastic bags to contain spills and protected from shock
• RoboCourier® Autonomous Mobile Robot

  Robot specimen transportation system
• Delivery Time Limits


  • Stat specimens must be transported, processed, and tested immediately
  • Routine blood specimens should ideally be delivered to the laboratory within 45 minutes of collection and centrifuged within 1 hour of arrival if serum or plasma is needed
  • The maximum time limit for serum or plasma separation according to CLSI standards is 2 hours after collection
  • Nonadditive and gel-barrier serum tubes, such as SSTs, must be completely clotted before centrifugation
  • Heparin gel-barrier tubes, such as PSTs, can be centrifuged right away
  • Specimens in gel barrier tubes do not require manual separation after they have been centrifuged (separator gel prevents glycolysis for up to 24 hours)

  
• Time limit exceptions


  • Ammonia specimens
  • Coagulation specimens
  • Glucose specimens in Sodium Fluoride tubes
  • Hematology specimens
• Exceptions to time limits

  1. Ammonia specimens

  2. Coagulation specimens

  3. Glucose specimens in Sodium Fluoride tubes
• PT results on unrefrigerated and uncentrifuged specimens are reliable for up to 24 hours after collection
• APTT test specimens require analysis within 4 hours of collection regardless of storage conditions
• Pediatric glucose specimens


  1. Test ASAP

  2. Difficult to inhibit glycolysis
• Hematology specimens


  1. Blood smears (from EDTA specimens) - prepare within 1 hour of collection

  2. EDTA specimens for CBCs - analyze within 6 hours; stable for 24 hours at RT

  3. EDTA specimens for ESR determinations - test within 4 hours if left RT or within 12 hours if refrigerated

  4. EDTA specimens for reticulocyte count - stable up to 6 hours at RT and up to 72 hours if refrigerated
• Molecular test specimens


  1. RNA substances are unstable

  2. Batch analysis - store plasma at 4°C for 48 hours

  3. If not analyzed within 48 hours, transfer into an aliquot tube and store at -80°C

  
• Urine specimens can be held at RT for up to 2 hours when not transported or analyzed promptly
• Body temperature


  36.4°C–37.6° C (37°C average)
• Room temperature


  20°C–30°C (25°C average)
• Frozen temperature


  −20°C or lower (some specimens require −70 °C or lower)
• Body Temperature Specimens


  1. Specimens need to be transported at or near normal body temperature of 37ᵒC

  2. Collect in a tube that has been prewarmed to 37ᵒC

  3. Small, portable heat blocks kept in 37ᵒC incubator

  4. Can hold this temperature for about 15 minutes after removal from the incubator

  5. Specimens can be wrapped in an activated heel warmer for transport
• Chilled Specimens


  1. Blood specimens that require chilling should be completely immersed in a slurry of crushed ice and water

  2. Large cubes or chunks of ice without water added do not allow adequate cooling of the entire specimen
• Specimens that must not be chilled

  • Coagulation specimens - can activate clotting factors and disrupt platelet function
  • Potassium - cold inhibits glycolysis
  • Arterial blood gas - should not be placed on ice if analyzed within 30 minutes of collection