Internal Quality control in Clinical Laboratories.pptx

04/17/2023Nazar Ahmed Mohamed Abd-

Alla(Sangoor)1

سبحان خلق منشئ كل

بقدر

Internal Quality control in Clinical Laboratoreis


Alla(Sangoor)2

NAZAR AHMED MOHAMED ABD-ALLA

Topics


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Quality definition.Quality Activity.Type of error in clinical laboratory.Specimens and Requests .Method selection, and Reagents

storage condition .Laboratory instruments.instruments and equipment calibration.SOPs.Use of calibrators and control material .

Topics


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Implementation of quality programsInterpretation 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 pathologist.

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, PPE, quality control, and turnaround time .


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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.Nazar Ahmed Mohamed Abd-

Alla(Sangoor)

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.

Nazar Ahmed Mohamed Abd-Alla(Sangoor) 04/17/202313

*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 *Pre-Analytical Error: 01- duplicate or missing requisitions 02- tests omitted from the requisition

03- incorrect ordering of tests04- patient identification error05- incorrect blood collection 06- specimen transport error07- specimen handling/processing in the lab

*Analytical errors: occur during the testing process. 01- deteriorated or wrong reagents

02- any instrument malfunction03- laboratorial error04- incorrect recording of test results


* Post Analytical Error:* 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.


Specimens and Requests


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1- Request forms. Request forms should include: Patient details.(age,sex,race,resedance) Specimen details .(type,preservatie,time of collection) Clinical Remarks .(spleenomegaly,hepatomegly,fever,join

pain)

2- Primary sample collection.• Patient Preparation• Containers selection• Blood Collection• Plasma Preparation• Specimen storage and Transportation



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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 CriteriaIncomplete 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.

METHOD VALIDATION

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“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. 04/17/2023

Nazar Ahmed Mohamed Abd-Alla(Sangoor)21

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


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

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

studyIdentity: 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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study

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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study

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

INSTRUMENT04/17/2023


6 8 10 12 14 16 180

2

4

6

8

10

12

14

16

18

HBG

HBG

Clinical laboratory instruments example


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Spectrophotometers .Water bath.Vortex.Hematology analyzer.Microplate reader & washer.Centrifuge.Flame photometers or ISE.Coagulometer.Hot air oven.

Maintenance and calibration of Photometers


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Includes checking for:Wavelength accuracyLinearity of instrumentStray lightBase line stabilityPhotometric accuracyShort circuitsCheck 0% TTemperature


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Micropipettes Calibration


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Gravimetric method (Distilled water

weighing method) (Recommended method)

Work Requirement:1. Calibration tools2. Double distilled water. 3. New compatible tip4. Analytical electronic balance(3-5 digits)5. Temperature controlled atmosphere6. 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 equilibriumCarefully 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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Systematic Error and Random Error


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Compare the Systematic Error

( Inaccuracy), Random Error

( Imprecision ) and F max with the values in the performance specification .

If the results fall within the specifications, the pipette is ready for use .

Otherwise check both Systematic Error and Random Error and when necessary recalibrate the pipette.

Table Shows The Maximum Permitted Errors( F Max )

PipettesType

Nominal volume

M.P.E (F Max )

Nominal volume

M.P.E (F Max )

Single channel pipettes

5 µl ±0.3 µl 200 µl ±2 µl

10 µl ±0.3 µl 250 µl ±2.5 µl

20 µl ±0.4 µl 500 µl ±5 µl

25 µl ±0.5 µl 1000 µl ±10 µl

50 µl ±0.8 µl 2000 µl ±20 µl

100 µl ±1.5 µl 5000 µl ±50 µl

Multi- channel pipettes

10 µl ±0.6 µl 250 µl ±5.0 µl

50 µl ±1.6 µl 300 µl ±6.0 µl04/17/2023


Table Shows The Recommended Specification

Nominal volume

Inaccuracy Imprecision Nominal

volume

Inaccuracy Imprecision

±≤%

(A) µl % ≤ µl %±≤ (A) µl % ≤ µl

5 µl 1.0 O.05 0.8 0.04 200 µl 0.5 1 0.2 0.410 µl 1.0 0.1 0.8 0.08 250 µl 0.5 1.25 0.2 0.5

20 µl 0.7 0.14 0.4 0.08 500 µl 0.5 2.5 0.2 1.0

25 µl 0.7 0.175 0.4 0.1 1000 µl 0.5 5 0.2 2.0

50 µl 0.7 0.35 0.4 0.2 10-100 µl 0.5 0.5 0.2 0.2

100 µl 0.5 0.5 0.2 0.2 20-200 µl 0.5 1 0.2 0.4

0.5-10 µl 1.0 0.1 0.8 0.08 25-250

µl 0.5 1.25 0.2 0.5

5-50 µl0.7 0.35 0.4 0.2 100-

1000 µl 0.5 5 0.2 2.004/17/2023


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

*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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2 .Controls for Qualitative Assays :

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

Assayedmean calculated by the

manufacturermust verify in the laboratory

Unassayedless expensivemust perform data analysis

“Homemade” or “In-house” pooled sera collected in the

laboratorycharacterizedpreserved in small quantities for

daily use


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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 Chartcontrol sample included in each assay

rundata plotted graphically (assay value

verses timeof 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 runMust 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 rejectedIf 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 reportedRequires 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 runso Four consecutive QC results for one level of

control are outside ±1SD, oro 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 runsTen consecutive QC results for one level of

control are on one side of the mean, orBoth 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

as accurate as 4C preparations 04/17/2023Nazar Ahmed Mohamed Abd-

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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 precisionwill 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 04/17/2023



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 04/17/2023Nazar Ahmed Mohamed Abd-

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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


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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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


Hierarchy of Documents


Policies

Processes

Procedures / Work Instructions

“what to do”

“how it happens”

“how to do it” - (SOPs)

Document Control


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Advantages:Assures that the most current version is used

Ensures availability when neededOrganizational tool


Summary: Document Preparation and Control Process


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Approval

Issue / Distribution

Review

Revision

Preparation

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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