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Pre-analytical Laboratory Errors. Tim Guirl MT (ASCP) Phlebotomy Instructor North Seattle Community College Health & Human Services Division. Objectives. Identify the significant pre-analytical errors that can occur during blood specimen collection and transport

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pre analytical laboratory errors

Pre-analytical Laboratory Errors

Tim Guirl MT (ASCP)

Phlebotomy Instructor

North Seattle Community College

Health & Human Services Division

  • Identify the significant pre-analytical errors that can occur during blood specimen collection and transport
  • Explain the various means of pre-analytical error prevention
  • List proactive steps to reduce potential pre-analytical errors associated with blood collection and transport
  • Three phases of laboratory testing: pre-analytical, analytical and post-analytical
  • Pre-analytical—specimen collection, transport and processing
  • Analytical—testing
  • Post-analytical—testing results transmission, interpretation, follow-up, retesting.
phlebotomy errors
  • Phlebotomy is a highly complex skill requiring expert knowledge, dexterity and critical judgment
  • It is estimated that one billion venipunctures are performed annually in the U.S.
  • Phlebotomy errors may cause harm to patients or result in needlestick injury to the phlebotomist
pre analytical errors
Pre-analytical errors
  • Pre- and post-analytical errors are estimated to constitute 90% of errors
  • Errors at any stage of the collection, testing and reporting process can potentially lead to a serious patient misdiagnosis
  • Errors during the collection process are not inevitable and can be prevented with a diligent application of quality control, continuing education and effective collection systems
types of collection errors
Types of Collection Errors
  • Patient Identification
  • Phlebotomy Technique
  • Test Collection Procedures
  • Specimen Transport
  • Specimen Processing
patient identification errors
Patient Identification Errors
  • Errors in correctly identifying the patient are indefensible
  • Reasons for patient identification errors
    • Proper positive patient identification procedures not followed
      • Patient identification from identification bracelet (inpatients)
      • Patient identification by asking patients to state or spell their full name (inpatients/outpatients)
      • Patient identification by staff or family member if patient unable to identify him/herself
patient identification errors8
Patient Identification Errors
  • Specimen tubes unlabeled
    • Requisition or collection tube labels not affixed to tubes
      • Requisition or collection tube labels in bag containing collection tubes
      • Requisition or collection tube labels rubber-banded to tubes
      • Collection tube labels not affixed to all tubes
      • Specimen collection tubes labeled insufficiently with at minimum patient’s full name, date/time of collection, phlebotomist’s initials
patient identification errors9
Patient Identification Errors
  • Collection tubes labeled with the wrong patient
    • Wrong computerized labels affixed to collection tubes at bedside
    • Collection tubes not labeled at the time of collection
    • Collection tubes incorrectly labeled by someone other than the phlebotomist who collects the specimen
patient complications
Patient Complications
  • Some patient variables that affect blood specimens
    • Diet
      • Fasting
    • Exercise
    • Obesity
    • Allergies to alcohol or iodine used to clean venipuncture site
      • Use alternative cleanser such as chlorhexidine
phlebotomy technique errors
Phlebotomy Technique Errors
  • Phlebotomy technique is important
    • Ensures test result validity
    • Minimizes trauma to patient
    • Minimizes potential for phlebotomist injury
    • Reduces recollections
  • Vein selection essential for successful venipuncture
    • Three veins in antecubital fossa in order of selection (1) median cubital (2) cephalic (3) basilic
phlebotomy technique errors12
Phlebotomy Technique Errors
  • Site Selection
    • Avoid sites with IV
      • Use alternative arm or draw below IV to avoid contamination/dilution from IV
      • Document arm if IV
    • Mastectomy—avoid site due to lymphostasis
      • Infection risk/alteration in body fluids and blood analytes
    • Edematous areas —avoid due to accumulation of body fluids
      • Possible contamination/dilution of specimen
phlebotomy technique errors13
Phlebotomy Technique Errors
  • Venous Access Difficulties
    • Obstructed, hardened, scarred veins
    • Veins difficult to locate
    • Use of Alternative sites
      • Top of hand/Side of wrist
      • Areas to avoid
  • Vein Collapse
    • Use of appropriate needle size
    • Smaller evacuated collection tube
phlebotomy technique errors14
Phlebotomy Technique Errors
  • Tourniquet Application
    • Tourniquet tied too close to the venipuncture site can cause hematoma
    • Veins may not become prominent if tourniquet is tied too high (more than 3 to 4 inches above venipuncture site)
    • Tourniquet left on longer than one minute can result in hemoconcentration, affecting some test results
      • Tourniquet should be released as soon as needle is in the lumen of the vein and blood flow established
phlebotomy technique errors15
Phlebotomy Technique Errors
  • Cleansing of venipuncture site
    • Thorough cleaning with alcohol
    • Allow alcohol to dry completely to avoid stinging sensation upon needle entry and hemolysis of sample
    • Samples such as blood cultures should be collected using iodine to cleanse site to ensure sterility of sample
      • Recollection rate for blood cultures ranges due to contamination is as high as 50% in hospitals with increased costs, patient overtreatment
phlebotomy technique errors16
Phlebotomy Technique Errors
  • Correct collection system
    • Evacuated tube system (Vacutainer) for large veins in antecubital fossa
    • Syringe for small, fragile veins or veins outside antecubital fossa
  • Venous access
    • Needle entry should be at 15 to 30 degrees depending on depth of vein
    • Needle entry should be in same direction as vein, centered over vein
    • Anchor vein to prevent movement during needle entry and to reduce pain to patient
test collection errors
Test Collection Errors
  • Order of Draw
    • Order of draw affects the quality of the sample and can lead to erroneous test results due to contamination with the additive from the previous blood collection tube
  • Hemolysis
    • Blood collected insufficient to amount of additive in tube,
    • Traumatic venipuncture
    • Blood collected from area with hematoma
    • Vigorous shaking of tubes after collection
    • Milking the site when collecting capillary samples and blood collected using a small diameter needle.
test collection errors18
Test Collection Errors
  • Timing of Collection
    • Timed Draws
    • Therapeutic Drug Monitoring
      • Peak and trough collection times
    • Basal State Collections
      • Fasting requirements—no food or liquid except water
    • Specimens affected by time of day, for example, cortisol
test collection errors19
Test Collection Errors
  • Improper collection tube drawn for test ordered
  • Collection tube not completely filled
    • Example—light blue top tube for Coagulation Studies. Incomplete filling results in specimen dilution and erroneous Prothrombin and aPTT test results.
test collection errors20
Test Collection Errors
  • Capillary Collections—finger stick or heel stick
    • Appropriate site
      • Heel stick—sides of the bottom surface of the heel
      • Finger stick—third or fourth fingers, perpendicular to fingerprint lines on fleshy pads on finger surface
    • Warming—Warm before collection to increase capillary blood flow near skin surface
    • Cleaning—cleanse site with alcohol and allow to air dry
capillary collections
Capillary Collections
  • Massaging site to increase blood flow
    • Milking site can cause hemolysis or tissue fluid contamination
    • Finger sticks—roll fingers toward fingertip at 1st finger joint several times
    • Heel sticks—gently squeeze infant’s heel before performing puncture.
  • Perform puncture while firmly squeezing finger or heel
  • Wipe away first two drops of blood
    • Ensure that full blood drop wells up each time
capillary collections22
Capillary Collections
  • Avoid touching capillary collection tube or micro collection tube to skin or scraping skin surface
    • Contaminates puncture site
    • Blood may become hemolyzed
  • Mixing micro collection tubes with additive frequently to avoid micro clots
  • Collecting tubes with additives first
  • Protecting tubes for bilirubin from light
blood specimen transport errors
Blood Specimen Transport Errors
  • Transport of blood specimens in the proper manner after collection ensures the quality of the sample
  • Timing
    • Some specimens must be transported immediately after collection, for example Arterial Blood Gases.
    • Specimens for serum or plasma chemistry testing should be centrifuged and separated within two hours
transport errors
Transport Errors
  • Temperature
    • Specimens must be transported at the appropriate temperature for the required test
      • On ice—ABGs, Ammonia
      • Warmed --98.6 degrees (37 C), cryoglobulins
      • Avoid temperature extremes if transported from via vehicle from other collection site
  • Transport Container
    • Some samples need to be protected from light, for example, bilirubin
    • Transport in leak-proof plastic bags in lockable rigid containers
error prevention
Error Prevention
  • Phlebotomy Education
    • Phlebotomists should have completed a standard academic course in phlebotomy and undergo thorough on-the-job training under the supervision of a senior phlebotomist
  • Continuing Education
    • Phlebotomists should participate in regular educational competency assessments (written and observational)
    • Professional Licensure
  • Phlebotomy Staffing
    • Adequate staffing to maintain collection standards
  • Technology
    • Use of barcode scanners for patient identification
questions and discussion
Questions and Discussion
  • How are pre-analytical errors prevented in your laboratory?
  • What technology do you use to prevent human error?
  • What systems does your hospital use to prevent errors by non-laboratory staff collecting blood?
  • What pro-active improvements would reduce the number of pre-analytical errors?