pre-analytical laboratory errors dr sami saeed associate professor/hod foundation university medical...

Pre-analytical Pre-analytical Laboratory Errors Laboratory Errors

Dr Sami SaeedDr Sami SaeedAssociate Professor/HODAssociate Professor/HOD

Foundation University Medical Foundation University Medical CollegeCollege

Path Lab, Fauji Foundation Path Lab, Fauji Foundation Hospital, Hospital,

Rawalpindi Rawalpindi Email: Email:

[email protected]@comsats.net.pk

ObjectivesObjectives

Identify the significant pre-analytical Identify the significant pre-analytical errors that can occur during blood errors that can occur during blood specimen collection and transportspecimen collection and transport

Explain the various means of pre-Explain the various means of pre-analytical error preventionanalytical error prevention

List proactive steps to reduce List proactive steps to reduce potential pre-analytical errors potential pre-analytical errors associated with blood collection and associated with blood collection and transporttransport

IntroductionIntroduction

Three phases of laboratory testing: Three phases of laboratory testing: pre-analytical, analytical and pre-analytical, analytical and post-analyticalpost-analytical

Pre-analytical—specimen collection, Pre-analytical—specimen collection, transport and processingtransport and processing

Analytical—testingAnalytical—testing Post-analytical—results transmissionPost-analytical—results transmission

Pre Analytical Phase

Specimen collection, handling and processing

Physiological variables such as the effect of lifestyle, age, gender, pregnancy and menstruation

Endogenous variables such as drugs etc


Some such as specimen variables can be controlled

Knowledge of uncontrollable variables need to be well understood


German Society for Clinical Chemistry and the German Society for Laboratory Medicine proposed comprehensive recommendations on the quality of diagnostic samples, handling of hemolytic, icteric and lipemic samples

Choice of anticoagulants to use, optimal sample size and analyte stability in sample matrix for each analyte

Recommendations of the German Society for Clinical Chemistry and the German Society for

Laboratory Medicine

Optimal sample volume: Twice the analytical volume of serum or plasma required for laboratory tests plus the dead volume of sample cup, replicates, and secondary tubes

In general, for testing 20 analytes in clinical chemistry, 3 to 4 mL of whole blood is needed to obtain heparinized plasma, while 4 to 5 mL of clotted blood is needed to express serum

2 to 3 mL of EDTA blood and citrated blood is sufficient to perform hematology and coagulation tests

Pre-analytical errorsPre-analytical errors

Pre (32-75%)- and post-analytical Pre (32-75%)- and post-analytical errors are estimated to constitute errors are estimated to constitute 90% of errors90% of errors

Clinical Chemistry 53:7 1338–1342 2007

Errors in the Total Test Process

Pre-analyticalAnalyticalPost-analytical

62%23%

15%

Types of ErrorsTypes of Errors Patient IdentificationPatient Identification

Phlebotomy TechniquePhlebotomy Technique

Test Collection ProceduresTest Collection Procedures

Specimen TransportSpecimen Transport

Specimen ProcessingSpecimen Processing

Patient Identification Patient Identification ErrorsErrors

Errors in correctly identifying the Errors in correctly identifying the patient are indefensiblepatient are indefensible

Reasons for patient identification Reasons for patient identification errorserrors Proper positive patient identification Proper positive patient identification

procedures not followedprocedures not followed Identification bracelet (inpatients)Identification bracelet (inpatients) Asking patients to state their full name Asking patients to state their full name

(inpatients/outpatients)(inpatients/outpatients) Patient identification by staff or family Patient identification by staff or family

member if patient unable to identify member if patient unable to identify him/herselfhim/herself


Collection tubes labeled with the Collection tubes labeled with the wrong patientwrong patient

Collection tubes not labeled at the Collection tubes not labeled at the time of collectiontime of collection

Wrong labels affixed to collection Wrong labels affixed to collection tubes at bedsidetubes at bedside

Collection tubes incorrectly labeled Collection tubes incorrectly labeled by someone other than the by someone other than the phlebotomist who collects the phlebotomist who collects the specimenspecimen

Patient Complications Patient Complications

Some patient variables that affect Some patient variables that affect blood specimensblood specimens DietDiet

FastingFasting

ExerciseExercise ObesityObesity Allergies to alcohol or iodine used to Allergies to alcohol or iodine used to

clean venipuncture siteclean venipuncture site Use alternative cleanser such as Use alternative cleanser such as

chlorhexidinechlorhexidine


Specimen tubes unlabeledSpecimen tubes unlabeledRequisition or collection tube Requisition or collection tube labels not affixed to tubeslabels not affixed to tubes

Requisition or collection tube labels Requisition or collection tube labels in bag containing collection tubesin bag containing collection tubes

Requisition or collection tube labels Requisition or collection tube labels rubber-banded to tubesrubber-banded to tubes

Collection tube labels not affixed to Collection tube labels not affixed to all tubesall tubes

Specimen collection tubes labeled Specimen collection tubes labeled insufficientlyinsufficiently

Phlebotomy ErrorsPhlebotomy Errors

Phlebotomy is a highly complex skill Phlebotomy is a highly complex skill requiring expert knowledge, requiring expert knowledge, dexterity and critical judgmentdexterity and critical judgment

It is estimated that one billion It is estimated that one billion venipunctures are performed venipunctures are performed annually in the U.Sannually in the U.S

Phlebotomy errors may cause harm Phlebotomy errors may cause harm to patients or result in needlestick to patients or result in needlestick injury to the phlebotomistinjury to the phlebotomist

Phlebotomy Technique Phlebotomy Technique ErrorsErrors

Phlebotomy technique is importantPhlebotomy technique is important Ensures test result validityEnsures test result validity Minimizes trauma to patientMinimizes trauma to patient Minimizes potential for phlebotomist injuryMinimizes potential for phlebotomist injury Reduces recollectionsReduces recollections

Vein selection essential for successful Vein selection essential for successful venipuncturevenipuncture Three veins in antecubital fossa in order of Three veins in antecubital fossa in order of

selection (1) median cubital (2) cephalic (3) selection (1) median cubital (2) cephalic (3) basilicbasilic


Venous Access DifficultiesVenous Access Difficulties Obstructed, hardened, scarred veinsObstructed, hardened, scarred veins Veins difficult to locateVeins difficult to locate Use of Alternative sitesUse of Alternative sites

Top of hand/Side of wristTop of hand/Side of wrist

Vein CollapseVein Collapse Use of appropriate needle size Use of appropriate needle size Smaller evacuated collection tubeSmaller evacuated collection tube


Site SelectionSite Selection Avoid sites with IVAvoid sites with IV

Use alternative arm or draw below IV to avoid Use alternative arm or draw below IV to avoid contamination/dilution from IVcontamination/dilution from IV

Document arm if IVDocument arm if IV

Mastectomy—avoid site due to lymphostasisMastectomy—avoid site due to lymphostasis Infection risk/alteration in body fluids and blood Infection risk/alteration in body fluids and blood

analytesanalytes

Edematous areasEdematous areas — —avoid due to avoid due to accumulation of body fluidsaccumulation of body fluids Possible contamination/dilution of specimenPossible contamination/dilution of specimen


Tourniquet ApplicationTourniquet Application Tourniquet tied too close to the venipuncture Tourniquet tied too close to the venipuncture

site can cause hematomasite can cause hematoma Veins may not become prominent if Veins may not become prominent if

tourniquet is tied too high (more than 3 to 4 tourniquet is tied too high (more than 3 to 4 inches above venipuncture siteinches above venipuncture site))

Tourniquet left on longer than one minute Tourniquet left on longer than one minute can result in hemoconcentration, affecting can result in hemoconcentration, affecting some test resultssome test results Tourniquet should be released as soon as needle is Tourniquet should be released as soon as needle is

in the lumen of the vein and blood flow establishedin the lumen of the vein and blood flow established


Cleansing of venipuncture siteCleansing of venipuncture site Thorough cleaning with alcohol Thorough cleaning with alcohol Allow alcohol to dry completely to avoid Allow alcohol to dry completely to avoid

stinging sensation upon needle entry and stinging sensation upon needle entry and hemolysis of samplehemolysis of sample

Samples such as blood cultures should be Samples such as blood cultures should be collected using iodine to cleanse site to collected using iodine to cleanse site to ensure sterility of sampleensure sterility of sample

Recollection rate for blood cultures ranges due to Recollection rate for blood cultures ranges due to contamination is as high as 50% in hospitals with contamination is as high as 50% in hospitals with increased costs, patient overtreatmentincreased costs, patient overtreatment

Test Collection ErrorsTest Collection Errors Order of DrawOrder of Draw

Order of draw affects the quality of the sample Order of draw affects the quality of the sample and can lead to erroneous test results due to and can lead to erroneous test results due to contamination with the additive from the contamination with the additive from the previous blood collection tubeprevious blood collection tube

HemolysisHemolysis Blood collected insufficient to amount of additive in Blood collected insufficient to amount of additive in

tube, tube, Traumatic venipunctureTraumatic venipuncture Blood collected from area with hematomaBlood collected from area with hematoma Vigorous shaking of tubes after collectionVigorous shaking of tubes after collection Milking the site when collecting capillary samples and Milking the site when collecting capillary samples and

blood collected using a small diameter needleblood collected using a small diameter needle. .

Order of Specimen Order of Specimen CollectionCollection

Blood culture tube Coagulation tube (citrate) Serum tube (with or without clot activator or gel

separator) Heparin (with or without gel separator) EDTA Oxalate/ Fluoride NCCLS (CLSI) H3-A5 standard, 2003

Test Collection ErrorsTest Collection Errors

Timing of CollectionTiming of Collection Timed DrawsTimed Draws Therapeutic Drug MonitoringTherapeutic Drug Monitoring

Peak and trough collection timesPeak and trough collection times Basal State Collections Basal State Collections

Fasting requirements—no food or liquid Fasting requirements—no food or liquid except waterexcept water

Specimens affected by time of day, for Specimens affected by time of day, for example, cortisolexample, cortisol

Test Collection ErrorsTest Collection Errors

Collection tube not completely filledCollection tube not completely filled Example— Incomplete filling results in Example— Incomplete filling results in

specimen dilution and erroneous specimen dilution and erroneous Prothrombin and aPTT test resultsProthrombin and aPTT test results

Test Collection ErrorsTest Collection Errors Capillary Collections—finger stick or heel Capillary Collections—finger stick or heel

stickstick Appropriate siteAppropriate site

Heel stick—sides of the bottom surface of the heelHeel stick—sides of the bottom surface of the heel Finger stick—third or fourth fingers, perpendicular Finger stick—third or fourth fingers, perpendicular

to fingerprint lines on fleshy pads on finger surfaceto fingerprint lines on fleshy pads on finger surface Warming—Warm before collection to increase Warming—Warm before collection to increase

capillary blood flow near skin surfacecapillary blood flow near skin surface Cleaning—cleanse site with alcohol and allow Cleaning—cleanse site with alcohol and allow

to air dryto air dry

Capillary CollectionsCapillary Collections

Massaging site to increase blood flowMassaging site to increase blood flow Milking site can cause hemolysis or tissue Milking site can cause hemolysis or tissue

fluid contaminationfluid contamination Finger sticks—roll fingers toward fingertip at Finger sticks—roll fingers toward fingertip at

11stst finger joint several times finger joint several times Heel sticks—gently squeeze infant’s heel Heel sticks—gently squeeze infant’s heel

before performing puncture. before performing puncture. Perform puncture while firmly squeezing Perform puncture while firmly squeezing

finger or heelfinger or heel Wipe away first two drops of bloodWipe away first two drops of blood

Ensure that full blood drop wells up each Ensure that full blood drop wells up each timetime

Capillary CollectionsCapillary Collections

Avoid touching capillary collection Avoid touching capillary collection tube or micro collection tube to skin or tube or micro collection tube to skin or scraping skin surfacescraping skin surface Contaminates puncture siteContaminates puncture site Blood may become hemolyzedBlood may become hemolyzed

Mixing micro collection tubes with Mixing micro collection tubes with additive frequently to avoid micro clotsadditive frequently to avoid micro clots

Collecting tubes with additives firstCollecting tubes with additives first Protecting tubes for bilirubin from Protecting tubes for bilirubin from

lightlight

Specimen Transport Specimen Transport ErrorsErrors

TimingTiming Some specimens must be transported Some specimens must be transported

immediately after collection, for immediately after collection, for example Arterial Blood Gases example Arterial Blood Gases

Specimens for serum or plasma Specimens for serum or plasma chemistry testing should be chemistry testing should be centrifuged and separated within two centrifuged and separated within two hourshours

Transport ErrorsTransport Errors TemperatureTemperature

Specimens must be transported at the Specimens must be transported at the appropriate temperature for the required appropriate temperature for the required testtest

On ice—ABGs, AmmoniaOn ice—ABGs, Ammonia Warmed --98.6 degrees (37 C), cryoglobulinsWarmed --98.6 degrees (37 C), cryoglobulins Avoid temperature extremes if transported Avoid temperature extremes if transported

from via vehicle from other collection sitefrom via vehicle from other collection site Transport ContainerTransport Container

Some samples need to be protected from light, for Some samples need to be protected from light, for example, bilirubinexample, bilirubin

Transport in leak-proof plastic bags in lockable Transport in leak-proof plastic bags in lockable rigid containersrigid containers

Physiological Pre Analytical Variables

TIME Increased/Decreased Cortisol Toward

evening and midnight Glucose tolerance test

values Afternoon SEASON Increased/Decreased Summer Vitamin-D ,

Triidothyronine 20% Winter Total

cholesterol (slight)Triglycerides

MENSTRUATION Increased/Decreased Serum iron and phosphate Cholesterol, lowest at

ovulation

CAFFEINE Increased/Decreased cAMP Free fatty acids Free ionic calcium Plasma renin and

catecholamine SMOKING Increased/Decreased Plasma Epinephrine Carboxyhemoglobin,

Hemoglobin, RBC, WBC, MCV, HDL-C

Tests ReferredTests Referred0101stst Jan 2013-30 Jan 2013-30thth

June 2013June 2013OPD Wards

Chemical Pathology 1,25,932 1,26,887

Hematology 79,840 81,257

Microbiology 32,159 30,541

Total 2,37,931 2,38,685

Total Number of ErrorsTotal Number of Errors

OPD and Wards: 196405 (41%)OPD and Wards: 196405 (41%)

The Errors!The Errors!Type of error Inpatients Outpatients

Hemolyzed sample

Clotted sample

Incorrect sample

No Label or ID

Insufficient sample

Incomplete Info (blood group)

Empty tube

Total

67566

53700

33764

16725

7608

5862

7664

192889

828

1015

456

857

208

-

152

3516

Causes, Probable (?)Causes, Probable (?)

Improper mixingImproper mixing Labeling by junior/untrained staffLabeling by junior/untrained staff Sample ordering system operated by Sample ordering system operated by

Nursing staffNursing staff Sample transport to lab by wards Sample transport to lab by wards

boys/ayasboys/ayas Lack of knowledge about sampling Lack of knowledge about sampling

requirements in PGT’srequirements in PGT’s

Review of the literature on laboratory errors Sector of the laboratory

Lapworth and Teal Clinical chemistry

Goldschmidt and Lent

Whole laboratory

Nutting et al.

Primary care

Plebani and Carraro Stat laboratory

Stahl et al. Whole laboratory

Hofgärtner and Tait

Molecular genetic tests onsite survey

(2 laboratories)

Molecular genetic tests questionnaire (101 sent, 42 respondents)

Preana-

lytical

phase

31.6% 53% 55.6% 68.2% 75% 44% 60%

Analytical

phase31.6% 23% 13.3% 13.3% 16% 31% 19%

Postana-

lytical

phase

30.8% 24% 30% 18.5% 9% 12.5% 15%

Multiple

phases6 % 12.5% 6%

Types of preanalytical errors at the Laboratory of San Raffaele Hospital, Italy

Type of error Inpatients Outpatients

Hemolyzed sample

Insufficient sample

Incorrect sample

Clotted sample

Incorrect identification

Lack of signature (blood group)

Empty tube

Lack or wrong compilation of the accompanying module

Sample not on ice

Tube broken in the centrifuge

Test not reserved

Urine not acidified

Open container

Module without signature

Urine volume not indicated

Total

8494

3256

1824

792

287

266

238

120

75

57

31

24

20

14

5

15,503

256

102

289

80

2

8

6

36

13

792

Error PreventionError Prevention Phlebotomy EducationPhlebotomy Education

Phlebotomists should undergo thorough on-the-Phlebotomists should undergo thorough on-the-job training under the supervision of a senior job training under the supervision of a senior phlebotomistphlebotomist

Continuing EducationContinuing Education Phlebotomists should participate in regular Phlebotomists should participate in regular

educational competency assessments (written educational competency assessments (written and observational) and observational)

Phlebotomy StaffingPhlebotomy Staffing Adequate staffing to maintain collection Adequate staffing to maintain collection

standardsstandards Technology Technology

Use of barcode scanners for patient identificationUse of barcode scanners for patient identification

Recognition of Pre analytical Variables Causing Changes in

Laboratory Results A 55-year-old man was hospitalized

with a serum potassium of 6.9 mmol/L on a non-hemolyzed sample obtained in an outpatient clinic. All other laboratory tests were normal. During hospitalization serum potassium values ranged from 3.9 - 4.5 mmol/L (normal 3.5 - 5.0 mmol/L).


Laboratory Results In OPD, blood was collected with the

application of tourniquet and fist clenching

In the ward, blood was collected through an in-dwelling catheter

Cause of pseudohyperkalemia was repeated fist clenching during tourniquet application intended to make the veins prominent

The contraction of forearm muscles causes release of potassium. This effect can lead to a 1-2 mmol/L increase in potassium with as much as 2.7 mmol/L increase


Laboratory Results Abnormal laboratory findings in

a 43 year old male: Alkaline phosphatase 5 IU/L (normal 45-115 IU/L), calcium 0.5 mmol/L (normal 2.1 - 2.6 mmol/L) and potassium 22.0 mmol/L (normal 3.5-5.0 mmol/L) on a non-hemolyzed sample.


Laboratory Results Plasma was obtained from blood

collected in a tri potassium EDTA tube

EDTA chelated magnesium and zinc required for the activity of alkaline phosphatase; EDTA also chelated calcium leading to its gross underestimation

Potassium in EDTA was responsible for raised K+to a physiologically impossible level.

DiscussionDiscussion

How are pre-analytical errors prevented How are pre-analytical errors prevented in your laboratory?in your laboratory?

What do you do to prevent human error?What do you do to prevent human error? What systems does your hospital use to What systems does your hospital use to

prevent errors by non-laboratory staff prevent errors by non-laboratory staff collecting blood?collecting blood?

What pro-active improvements would What pro-active improvements would reduce the number of pre-analytical reduce the number of pre-analytical errors? errors?

Questions?Questions?

pre-analytical laboratory errors dr sami saeed associate professor/hod foundation university medical...

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