internal quality control in clinical laboratories hematology(2)

11/2/2015 Nazar Ahmed Mohamed Abd-

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c


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Internal Quality control

in Hematoogy

Laboratoreis


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NAZAR AHMED MOHAMED ABD-ALLA

BSC - OMDURMAN AHLIA

HIGH DOPLOMA DGREE - ELZAEM EL-AZHARY

FORMER HEAD OF HEMATOLOGY & BLOOD BANK

MINISTRY OF HEALTH – LABORATORY ADMINISTRATION

KHARTOUM STATE

MARKETING MANAGER-LAB EQP –DIVISION

ALGAM COMPANY FOR DRUGS & CHEMICAL LTD

Topics


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Quality definition.

Quality Activity.

Type of error in clinical Hematology laboratory.

Specimens and Requests .

Method selection, and Reagents storage condition .

instruments and equipment calibration.

SOPs.

Use of calibrators and control material .

Topics


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Implementation of quality programs

Interpretation of internal quality results.

Corrective action.

Turn around time.

Documentation.

Whats Quality

quality is defined as the totality of features and characteristics

of a product or service that bear on its ability to satisfy stated

or implied needs.

Medical laboratories must provide a high quality service by

producing accurate, precise, relevant and comprehensive data

that can be applied to the medical management of patients.

tests requested must be appropriate to the medical problem,

must be analytically correctly performed and their results

interpreted correctly.


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Quality assurance: Part of quality management focused on

providing confidence that quality requirements will be

fulfilled . witch contain many activity.

Quality control: Part of quality management focused on fulfilling

quality requirements.

Quality management system: Management system to direct and

control an organization with regard to quality.


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Appropriateness of tests can only be obtained by a dialogue

between the clinician and the medical lab-specialist.

Correct analytical results are based on:

(i) quality management within the laboratory.

(ii) the quality of industrially prepared reagents (kits) and

instruments .

(iii) quality management of the pre-analytical phase outside

the laboratory along with analytical & post-analytical phase.

A bad system, a wrong sampling or a kit with poor

performance can never produce a reliable result, even in a

laboratory with the best quality management system.


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principles aspects of making

reliable analytical measurements:

1. Analytical measurements should be made to satisfy an

agreed requirement.

2. Analytical measurements should be made using methods

and equipment that have been tested to ensure they are fit

for purpose.

3. Staff making analytical measurements should be both

qualified and competent to undertake the task.


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principles aspects of making

reliable analytical measurements:

4. There should be a regular independent assessment of the

technical performance of a laboratory.

5. Analytical measurements made in one location should be

consistent with those elsewhere.

6. Organizations making analytical measurements should

have well defined quality control and quality assurance

procedures.


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Quality Assurance

Quality assurance is a comprehensive and systematic process

that strives to ensure reliable patient results.

This process includes: Every level of laboratory operation.

*Phlebotomy services.

*competency testing.

*error analysis.

*standard protocols.

*quality control.

*turnaround time .


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objective of quality assurance

1. Lab result must be timely reliable and valid to be used

correctly.

2. Focus on laboratory staff training and competency.

3. Give grantee of the reliability of the test result


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Quality assurance requirements 1. Performance of internal quality control (IQC).

This is based on the repeat testing of a control sample in each

assay run and then comparison of the assay result with its

expected result.

It is performed in real time and is used to pass or fail a series of

results.

2. Performance of external quality assessment (EQA)

this based on a sample that is sent to a group of laboratories.

The relative position of the laboratory in relation to the others is

calculated retrospectively.

In combination, IQC and EQA can monitor both precision and

accuracy.

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*QA activities encompass all of the non-analytic activities,

those activities that are not part of the clinical testing

process.

*The laboratory organizes it activities to provide the best

possible health care to the patient.

Nazar Ahmed Mohamed Abd-Alla(Sangoor)

QA activities

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* A. management and monitoring personnel, B. using quality materials (reagents instruments, supplies, etc.), C. using established procedures and established statistics (a procedure manual), D. specimen collection, identification, transport, accession, and handling prior to testing, E. reporting results, F. fee charges for tests performed, G. using corrective actions to obtain desired results, H. monitoring patient satisfaction.


Examples of QA Activities

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*The Clinical laboratory is concerned about quality and

accuracy of the tests that are reported to primary care

givers.

*The laboratory monitors where these errors can appear

that will affect the accuracy of test results.

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NON-CONFORMING RESULTS

In laboratory practice many non-conforming results may

appear.

These results are divided in two major categories:

• Errors: Non-conforming results with “statistical meaning”.

This category includes all the “wrong” laboratory measures

due to non-human action.

• Mistakes: Non-conforming results with “no statistical

meaning”. This category contains all the human errors e.g.

mixing up samples.

Another classification of errors and mistakes is based on the

time and the stage they appeared in laboratory practice.


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*These errors can occur prior to the test analysis and if they manifest, they are called preanalytical errors or variables.

*If the error occurs during the testing process, then it become an analytical error.

*If the error appears after the test is performed and reported, then it is known as a post-analytical error.

*The preanalytical error occurs before the test is performed. This error source can occur at the beginning of test ordering and filling out the requisition.


Type Of Error

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*type of error based on the time

*Pre-Analytical Error:(specimen collection and transport)

01- duplicate or missing requisitions

02- tests omitted from the requisition 03- incorrect ordering of tests 04- patient identification error 05- incorrect blood collection 06- specimen transport error 07- specimen handling/processing in the lab *Analytical errors: (specimen processing in the lab)

occur during the testing process.

01- deteriorated or wrong reagents 02- any instrument malfunction 03- laboratorial error 04- incorrect recording of test results


* Post Analytical Error:(reporting and interpretation of results)

* Examples of these are: 01- failure to notify the physician of critical values: (Critical values may imply a life-threatening situation for the patient and are brought to the immediate attention of the physician and/or the patient care area responsible for the patient ). 02- failure to report test results in a timely manner. 03- placement of report in the chart of the wrong patient 04- miscommunications that are detrimental to the patient regarding the tests performed.


Pre-Analytical Error

Specimens and Requests


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1- Request forms:

Request forms should include:

Organization name and full address and telephone ,fax number & E.mail.

Referring doctor name and telephone number.

Patient details.(age,sex,race,resedance)

Specimen details .(type,preservatie,time of collection)

Clinical Remarks .(spleenomegaly,hepatomegly,fever,join pain)

Treatment history (any type of medication e.g asprine,sulfanomide;ect).

Tests ordering.(CBC,Urine general,lipid profile ………….. Ect)

Signture of cliniciant order the test.

2- Primary sample collection:

• 1- Patient Preparation:

*Avoiding stress and exercise witch increase

Cell concentration, coagulation factors(v111),tissue

plasminogen activator(T-PA) with increase fibrinolytic

activity).

*Avoid prolonged use of tourniquet. and patient

position (lying or standing to avoid

haemoconcentration) also position of the arm witch

cause fluctuation of about 5-10% in the blood count .

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2-Containers selection and type of anticoagulant:

e.g the most suitable one for haematology is K₂EDTA in concentration of 1.2-2.2mg/ml witch cause less cellular

change(recommended by ICSH).

K₃EDTA also can used but it cause significant shrinking of the

red call with decrease of about 1-2%in the MCV.

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*other Example is the amount of sodium citrate when the amount of citrate is high and the amount of blood is low the excess sodium citrate consume ca²+ present in the reagent.

& this prolong the PT&APTT. the opposite case lead to microclot as a matter this Couse shortness of APTT

3-BloodCollection:

way of collecting the sample (venous blood or capillary

blood)

in capillary blood improper technique can cause (presence

of micro clots or platelets clumps low platelets count

reported by cell counter.

Also delay sample lead to factor deterioration witch lead to

prolongation of PT & APTT(in coagulation)


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•*Avoid dilution and or contamination from flushing solution while drawing the blood from indwelling line or catheter.

•*(Contamination with heparin couse prolongation of APTT (in coagulation)) * When intravenous solution is being administrate in patient arm the blood drawing should be from the opposite arm

The recommended order of draw is:

• Blood culture tube

• Coagulation tube

• Serum tube with or without clot activator, and with or without

gel separator

• Heparin tube, with or without gel separator

• EDTA tube

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6-Specimen storage and Transportation:

*for sample transport : (tray should have protective cover ,

suitable environment require preventing deterioration of the

sample , person carrying the sample should be follow the

universal safety regulation.


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: mislabeling of sample is very serious labeling of the sample-4error witch can result as:( collecting from wrong patient , subsequent specimen mix –up , transcription error)

Plasma Preparation:-5 spaciely in case of coagulation the preparation of the plasma is very critical.

•The accepted goal of centrifugation of coagulation specimens is to produce platelet-poor plasma with a platelet count < 10×10⁹ /L< 10×10³/L1.

•* This may be accomplished by centrifuging specimens at 1500 g for 15 minutes or longer at room temperature.



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3- Samples acceptance criteria:

Complete request form.

Patient identification.

Suitable container selected.

Sufficient amount of blood collected.

Sample labeled properly.

Sample prepared properly.

Sample separated and store properly.



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4- Samples Rejection Criteria:

Incomplete request form.

Rung Patient identification.

Unsuitable container selected.

Unlabelled or incorrectly labeled sample.

Haemolysed sample.

Sample changes due to :

concentration changes

compostion changes.

bacterail changes.

and enzymatic changes.

Analytical errors

METHOD VALIDATION

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Validation refers to establishing documented evidence that a process or

system, when operating within established parameters, can perform

effectively and reproducibly to produce a result meeting its

predetermined specifications and quality attributes.

“Method validation” is a term used for the suite of procedures to which

an analytical method is subjected.

to provide objective evidence that the method, if used in the manner

specified, will produce results that conform to the statement of the

method validation parameters.

ISO Definition

1. The process of establishing the performance characteristics

and limitations of a method and the identification of the

influences which may change these characteristics and to

what extent.

* Which analytes can it determine in which matrices in the

presence of which interferences? Within these conditions

what levels of precision and accuracy can be achieved?

2. The process of verifying that a method is fit for purpose,

i.e. for use for solving a particular analytical problem.


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Continue: Method validation

Method validation involves the evaluation of the fitness of

analytical methods for their purpose.

The process of proving that an analytical method is

acceptable for its intended purpose.

the concept of fitness for purpose, a method is validated for

a particular use under particular circumstances. If those

circumstances vary, then the method would need to be re-

validated at least for the differences.


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METHOD VALIDATION


Error assessment is what method validation is about.

However, before getting to the assessment of errors, you

have to first select the method to be validated.

Method selection is a different process that needs to be

understood in relation to the validation process that will

follow.

Importance of Method Validation Practices


Laboratory regulations require that method performance for any new method be "verified" prior to reporting patient test results.

Precision and accuracy are specifically identified, along with analytical sensitivity, analytical specificity, reportable range, reference values, and any other applicable characteristic.

Types of Errors to be assessed by

method validation


Errors based on the stage

imprecision or random errors,

inaccuracy, bias, or systematic errors, which can be of two

types

*constant systematic error or

*proportional systematic error.

All these errors can be recognized when a group of

measurements are compared to the correct or true values.

Verification

Verification refers to the ability to make sure that the test

method you are using conforms to manufacturer

specifications.

Much of the work of method validation is done by

international organizations that publish standard methods. The

reason such methods appear to be written in a kind of legalese

is that there must be no doubt as to what the method is and

how it should be implemented.

* When accuracy and precision data are published from

interlaboratory trials, there is some confidence that the

method has undergone extreme scrutiny and testing.


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Verification

A laboratory that uses a method for the first time should spend

some time in going through the analysis with standard materials

so that when used with field samples, the method will yield

satisfactory results.

This is verification and must be done to an appropriate level

before any method is used. By its nature, (verification comes

under the heading of Single Laboratory Validation).


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Method performance parameters assessed

in a method validation study

Identity: Measurement correctly applies to the stated measurand.

Selectivity Specificity: Determination of the extent of the effects

of interfering substances and the ability of the method to measure

the measurand; analysis in different matrices covered by the scope

of the validation.

Limit of detection: Minimum value of the measurand at which the

presence of the analyte can be determined with a given probability

of a false negative, and in the absence of the analyte, at a given

probability of a false positive.

[Limit of determination] Minimum value that can be obtained

with a specified measurement uncertainty


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Calibration [linearity] Model parameters [sensitivity] :Adequacy

of the calibration model; parameters with uncertainties.

Calibration range [linear range] Range of values of the

measurand in which the validation holds

Bias and recovery [accuracy] :Demonstration of the absence of

significant systematic error after corrections have been made for

bias and/or recovery


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Robustness or ruggedness: Ability of method to remain

unaffected by small variations in method parameters (some

authors make the distinction bebetween the property

robustness and a ruggedness test in which deliberate changes

are made in a method to assess the robustness)


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Method Selection


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1. General Characteristics:

Made in ,Expire date, Package Content, Accessories, Package size ,Stability after open, and Reagent storage considerations.

2. Application Characteristics:

Specimen type, Sample volume, Turnaround Time, Stability of reaction product, Cost-per-test, Filter used, and Safety considerations

3. Methodology Characteristics:

Type of Reaction, Reaction Principle, Measurement reaction, Temperature, and Time period of measurement.

Experiments for estimating analytical errors


METHOD COMPARISSION FOR HBG

ESTIMATION BETWEEN TOW DIFFERENT

INSTRUMENT


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0

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HBG

HBG

METHOD COMPARISSION FOR HBG ESTIMATION

BETWEEN TOW DIFFERENT INSTRUMENT


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

medonic HBG

mindrays HBG

METHOD COMPARISSION FOR HBG ESTIMATION

BETWEEN TOW DIFFERENT INSTRUMENT


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

medonic HBG

mindrays HBG

Micropipettes Calibration


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Gravimetric method (Distilled water weighing method) (Recommended method)

Work Requirement:

1. Calibration tools

2. Double distilled water.

3. New compatible tip

4. Analytical electronic balance(3-5 digits)

5. Temperature controlled atmosphere

6. Small plastic beaker.

Checking Micropipettes Calibration


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Weighing Should takes place at 20-25ċ constant to ± 0.5ċ.

Set the desire testing volume of your pipette.

Carefully fit the tip onto the tip cone.

Aspirate the distilled water 5 times( Humidity equilibrium

Carefully aspirate the fluid, keeping the pipette vertical.

Pipette distilled water into a tred container and read the weight in mgs.

Repeat at least five times (ten times )and record each result in mgs.

Checking Micropipettes Calibration


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Convert the recoded weight to volume (V1) either

by divide the weight of the water by its density ( at

20ċ : 0.9982 ) or by multiply the weight by the Z

correction factor (= 1.002899 µl/mg at 20Ċ ).

Calculate the mean volume (V1)

Calculate the standard d deviation SD.

Calculate the Coefficient of Variation.

Calculate the Inaccuracy and Imprecision .

Calculate the F max value.


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Standard Operating Procedures


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SOPs are written , up to date instructions and information

which cover in details how to perform individual tests to

insure the correct use , availability , reliability , timeliness,

and reporting of blood tests and correct interpretation of the

test result

01.06.2011/Syllabus of 5 years/طريقة كتابة اجراء قياسى (SOP).doc

*Quality control (QC) encompasses quality assurance as it focuses on analytical activities that are associated with the testing process. QC consists of: A. running control samples with patient samples, B. using established statistical methods to determine reliability of test procedures and test results, C. monitoring instrument and laboratorial performance.


Quality control

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Quantitative QC Materials


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Calibrator: a solution which has a known amount of analyte weighed in or has a value determined by repetitive testing using a reference or definitive test method

Control: material or preparation used to monitor the stability of the test system within predetermined limits

Sources for Control Materials


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Commercial product.

Diagnostic samples (qualitative QC).

“Homemade” or “In-house”.

Obtained from:

Another laboratory .

EQA provider.


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Parallel Testing.-Validation of new controls

*Whenever possible, new lots of control material must be assayed in parallel alongside the current in use lot. *This is to enable the calculation of laboratory QC ranges and to demonstrate that the QC material is performing as expected.


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Controls for Quantitative Assays:

a. In order to validate new controls, the new lot of controls will be run in parallel with the old lot of controls 2-3 times a day for 5-10 days, to give a minimum of 20 values to enable the calculation of laboratory specific QC ranges. The mean and QC ranges for the new lot of controls will be reviewed and signed off by the laboratory supervisor or director before being put into use.


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b. For hematology the new lot of controls should be

run in parallel with the old lot of controls to give a

minimum of 10 values over a period 5 days if possible.

The mean and ranges for the new lot of controls will

be reviewed and signed off by the laboratory

supervisor or director before being put into use.


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Controls for Qualitative Assays: . 2

Each new lot of QC for qualitative assays must be run and give an expected response. The lot of controls will

be reviewed and signed off by the laboratory

supervisor or director before being put into use.


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Types of Control Materials

Assayed mean calculated by the manufacturer must verify in the laboratory

Unassayed less expensive must perform data analysis

“Homemade” or “In-house” pooled sera collected in the laboratory characterized preserved in small quantities for daily use

Levey-Jennings Chart


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o A graphical method for displaying control results and

evaluating whether a procedure is in-control or out-of-control

o Control values are plotted versus time

o Lines are drawn from point to point to accent any trends,

shifts, or random excursions

Levey-Jennings Chart

control sample included in each assay run

data plotted graphically (assay value verses time

of day)

control (or confidence) limits

mean

standard deviation (usually + 2 SD)

if control limits are not met, then no patient

samples run in that batch can be reported.

if control limits are met, then patient samples run

in that batch can be reported


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QC changes detectable with Levey-

Jennings plots

Drift: control value moves progressively in one

direction from the mean for at least 3 days e.g

deterioration of reagent or control

Dispersion :increase in random errors e.g

inconsistency in technique

Shift: sudden problem develops e.g instrument

malfunction or technique change


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Findings Over Time


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Ideally should have control values clustered about the mean

(+/-2 SD) with little variation in the upward or downward

direction

Imprecision = large amount of scatter about the mean.

Usually caused by errors in technique

Inaccuracy = may see as a trend or a shift, usually caused by

change in the testing process

Random error = no pattern. Usually poor technique,

malfunctioning equipment

Levey-Jennings Chart - Record and Evaluate the Control Values


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80

85

90

95

100

105

110

115

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Mean

Day

+1SD

+2SD

+3SD

-1SD

-2SD

-3SD

What are the "Westgard rules”


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They are different combination of rules depending on the number

of control being used, the total allowable error, and your work

environment.

rules That are used as conjunction with each other to provide a

high level of errors detection, while reducing the incidence of

false rejection.

Typical rules combination


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For control run in multiples of 2 “ typical chemistry”

13s / 22s / R4s / 41s / 10 x

For control run in multiples of 3“ typical

haematology,coagulation, and immunoassays”.

13s / 2 of 32s / R4s / 31s / 12 x

Westgard Rules

(Generally used where 2 levels of control

material are analyzed per run)


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12S rule

13S rule

22S rule

R4S rule

41S rule

10X rule

Westgard – 12S Rule


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“warning rule”

One of two control results falls outside

±2SD

Alerts tech to possible problems

Not cause for rejecting a run

Must then evaluate the 13S rule

12S Rule = A warning to trigger careful inspection of

the control data


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Mean

Day

+1SD

+2SD

+3SD

-1SD

-2SD

-3SD

12S rule

violation



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If either of the two control results

falls outside of ±3SD, rule is

violated

Run must be rejected

If 13S not violated, check 22S

13S Rule = Reject the run when a single control

measurement exceeds the +3SD or -3SD control limit


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Mean

Day

+1SD

+2SD

+3SD

-1SD

-2SD

-3SD

13S rule

violation



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2 consecutive control values for the same level fall outside

of ±2SD in the same direction, or

Both controls in the same run exceed ±2SD

Patient results cannot be reported

Requires corrective action

22S Rule = Reject the run when 2 consecutive control

measurements exceed the same

+2SD or -2SD control limit


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Mean

Day

+1SD

+2SD

+3SD

-1SD

-2SD

-3SD

22S rule

violation

Westgard – R4S Rule


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One control exceeds the mean by –2SD, and the other

control exceeds the mean by +2SD

The range between the two results will therefore exceed 4

SD

Random error has occurred, test run must be rejected

R4S Rule = Reject the run when 1 control

measurement exceed the +2SD and the other exceeds

the -2SD control limit


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Mean

Day

+1SD

+2SD

+3SD

-1SD

-2SD

-3SD

R4S rule

violation



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o Requires control data from previous runs

o Four consecutive QC results for one level of control are

outside ±1SD, or

o Both levels of control have consecutive results that are outside

±1SD

41S - reject when 4 consecutive

control measurements exceed the

same mean ± 1s limit.


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http://www.westgard.com/images/mrf6.gif

Westgard – 10X Rule


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Requires control data from previous runs

Ten consecutive QC results for one level of control are on

one side of the mean, or

Both levels of control have five consecutive results that are on

the same side of the mean

10x Rule = Reject the run when 10 consecutive control

measurements fall on one side of the mean


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Mean

Day

+1SD

+2SD

+3SD

-1SD

-2SD

-3SD

10x rule

violation

Moving Averages (Bull’s method)

large laboratories (built into blood analysers) assumes the

population sampled each day remains constant

therefore the calculated indices (MCV, MCH and MCHC)

remain stable

determine mean indice values for each batch of 20 patients,

plot on control chart

any change: instrument or technical fault


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Moving Averages (Bull’s method)

For the interpretation of Bull’s charts two rules have been

proposed

13%. Bull’s moving average exceeds the limit ± 3%.

32% . The mean value of three successive Bulls’ moving

averages exceeds the limit ± 2%.


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Moving Averages

MCV = Hct

RCC

MCH = Hb

RCC

MCHC = Hb

Hct

Changes in the moving

averages graphs indicate

where the problem

might be in the system.

eg. If the light source

for Hb is becoming

weak, then the

calculated MCH and

MCHC values will fall


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Moving averages

CAUSE MCV MCH MCHC

LowHb no change low low

High Hb no chang high high

Low RCC high high no change

High RCC low low no change

Low Hct low no change high

High Hct high no change low


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Duplicate tests on patient samples

tests precision

will not detect incorrect calibration

(accuracy)

smaller laboratories

METHOD

test 10 samples

repeat the tests

calculate the difference between pairs of results

and derive a standard deviation

SD should always be < 2SD


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Check tests on patient samples

monitors day-to-day precision (small lab)

detects deterioration within apparatus and

reagents

METHOD

» select 3-5 normals in the afternoon, record and

average values (WCC, RCC, Hb). Store at 4oC.

» re-assay same samples next morning

» tests should agree within 2SD

Must ensure there has been no change in samples


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Delta check method

Delta check is the difference between the current value of one person and

the previous one.

Delta check = Current value – Previous value

Delta check% = (Current value – Previous value) 100/Current

value .

Delta check detect random errors using previous values of

individual patient.


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Delta check

reasons of delta differences:

1. The “intra-individual” biological variation of the analyte

2. The analytical variation ,

3. The pre-analytical variation .

4. The improvement or deterioration of the patient’s health.

5. Errors and mistakes in the pre-analytical, analytical and

post-analytical stage.


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Corrective action

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Errors assessment and management:

Change Old Habits - Recognize Problems.

Bad habit Repeat the control .

Inspect the control charts or rules violated to determine type of error.

Relate the type of error to potential causes.

Consider factors in common on multitest systems

Relate causes to recent changes

Verify the solution and document the remedy

POST ANALYTICAL 1- Written of the report in satnder format :

2- Delta check :the blood count parameters should not differ from

recent test in the previous 2-3 weeks by more than a certain amount.

assuming that the patient clinical condition has not altered

significantly.

-For HBG & RBC 10%.

-For WBC 20-25%.

-For Platelets 50%.

3-Alert the clinician the critical values:

HBG ˂ 6 , Platelets ˂ 1000cell/cumm ,INR ˃ 2 ,APTT ratio ˃ 2

Peripheral blood picture: presence of malaria & or blast cells


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4- Turn around Times (TATs):


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Laboratory test turnaround times (TATs) In contrast to laboratorians, the majority of clinicians defined a TAT start time as test ordering, and a TAT ending time as result reporting.

Timely reporting of patient tests can increase efficiency of care and improve customer satisfaction.

In study done 2008 found that postanalytical phase accounted

for 64-88% of total tumround time, the pre-analytical phase

for 7-17%, and the analytical phase for 2-29%.


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Sample post analytical

Sample retention:

If needs to repeat the examination.

In case of requested other infestigatione.

Sample diposale: the sample dispose according to

specification.


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Documentations

Definitions


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*Forms: Blank form design to special work to be fill by data at time of use.

*Records: worksheets, forms, charts, labels, Used to capture information, activities, or results when performing a procedure

*Documents: written policies, process descriptions, procedures, and forms Used to communicate information

May be paper or electronic

Documents and Records • Document control policy

– Creation, review, and modifying documents and records and forms

• Procedures, processes, and policies

– Format,

– Approval process

– Flowcharts

• Records retention and disposition

– How long to retain records

– How to dispose of records


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External quality control (EQC)

External quality control or external assessment scheme

(EQAS) or proficiency testing program (PT):

refer to the process of controlling the accuracy of an analytical

method by interlaboratory comparisons.


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BASIC IDEA OF EQAS

1. The EQAS coordinator prepares and sends to the

participants of the scheme one or two samples from the same

pool.

2. The samples are assayed by the laboratories using the same

equipment and reagents as they do in routine for the patients’

determinations.

3. The EQAS coordinator gathers all the results and it groups

them (peer groups) according the laboratories analytical

methods, analyzers or any other criteria.


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BASIC IDEA OF EQAS

4. The EQAS coordinator calculates the target value

(consensus mean) and its total variation (expressed as

standard deviation) of the laboratories results.

5. If any of the laboratories has values outside of the control

limits (target value ± allowable variation) then this laboratory

is considered “out of control”.

6. The “out of control” laboratories have to correct their

analytical procedures.


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EQAS has its own charts and statistics.

One of the most important statistics is the “Standard

Deviation Index” (SDI).

SDI shows the distance of the laboratory results from the

consensus mean. It quantifies the inaccuracy of the analytical

method.

It is similar to Z-score (equation ) and it is calculated by the

formula:

SDI = laboratory result -Mean value of peer group

Strandard deviation of peer group


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Four rules are usually employed for SDI evaluation

1- 2/51SDI. Two from five successive control limits exceed

1 SDI. It is a warning rule.

2- X1.5 SDI . The mean value of five SDI values exceeds the

limits ±1.5 SDI. It reveals a lasting systematic error.

3-13SDI. One value exceeds the limits ±3 SDI.

4- R4SDI. The range (R) between the lower and higher SDI

values is over ±4 SDI.


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Precision Index and Coefficient of Variation

Ratio (CVR) External quality assessment schemes quite often use two

different statistics for the measurement of precision, the

Precision Index (PI) and the Coefficient of Variation Ratio

(CVR).

PI = Standard deviation of laboratory

Strandard deviation of peer group

The control limits of PI are < 2.

CVR = CV of laboratory /month

CV of peer group/ month

The combined SDI/CVR chart has the ability to evaluate the

total analyte’s performance(precision and accuracy).

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ANY QUESTION?

SUMMARY


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Pateint preparation, and good specimen collection,

preparation , handling, and storage of specimen.

Clinical Laboratory instruments daily, weekly, and monthly

maintenance and calibration done regular.

Micropipettes recalibration takes place monthly .

Good clinical method selected, and Reagents storage

condition verified by monitoring of refrigerators

temperature.

SUMMARY


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SOPs written, approved ,and followed carefully, then Sops critical point check list used daily.

MORE than one levels of control sera at least should used in all batches with patient samples.

Results of control sera register in quality book and blotted in levey Jennings chart.

Westgard rules used as guidance for acceptability or rejection of patient results applied.

Errors assessment and management takes place, and corrective action documented.

Turn a round time to all investigation verify monthly.

Documentation (to all lab activities)


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internal quality control in clinical laboratories hematology(2)

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