Quality control of the automated analysers used in hematology.

1. QUALITY CONTROL IN
HEMATOLOGY
DR YOGEETA TANTY

2. WHAT IS QUALITY?
• A measure of excellence .
• A state of being free from defects,
deficiencies, and significant variations .
• Brought about by strict and consistent
adherence to measurable and verifiable
standards.

3. QUALITY ASSURANCE
• Quality assurance(QA) in a laboratory is intended to
ensure reliability of the laboratory tests.
• A QA program should include standardization of tests
and of instruments in order to achieve acceptable
levels of precision and accuracy.

4. QUALITY CONTROL
Quality control (QC) is a procedure designed to detect,
reduce and correct deficiencies in the lab’s internal
analytical process.
It should be done prior to the release of patient results
and to improve the quality of the results reported by
the laboratory.

5. Important aspects of QC in hematology
are-
• Calibration of automated instruments.
• Monitoring of accuracy and precision of
instruments and procedures.
• Verifying the reliability of test results.

6. CALIBRATION
• It is a primary process to standardize the instrument
for accuracy.
• It is done to compare the measurement values
delivered by a device with those of calibration
standard of known accuracy.
• According to NABL 112 , all instruments should be
calibrated according to maufacturer’s guidelines
atleast once a year..
• And periodic calibration verification should be carried
out after preventive maintenance.

7. Pre analytical Post
analytical
Analytical
QUALITY CONTROL

8. PRE-ANALYTICAL
• Factors that affect the lab results due to
handling of specimen sample prior to
analysis.
• Misidentification of patient
• Mislabeling of specimen
• Fasting state
• Alcohol consumption
• Dehydration

9. • Prolonged use of tourniquet
• K2 EDTA causes less cellular damage and is
recommended by The International Council For
Standardisation In Hematology (ICSH).
• Improper techniques like squeezing can cause microclots
or platelet clumps.
• Smear preparation
• Ensuring proper drying of the smear

10. QUALITY CONTROL IN
ANALYTICAL PHASE
INTERNAL QC EXTERNAL QC
• Process that monitors accuracy It compares one’s lab
results to
and reproducibility of test results other labs.
through the use of controls. Serves to evaluate internal
• It is helpful for making immediate QC.
decisions. Maintains long term
accuracy
Ensures the lab is
performing to external standards.

11. • Accuracy: Reflects how close a measurement is to
the correct or accepted value.
• Precision : (reproducibility) is the closeness of values
when a test is repeated a number of times.

13. INTERNAL OR INTRA-
LABORATORY QUALITY
CONTROL
• Internal assessment of Analytical quality by regular
measurement of known/ assigned value samples.
• Analysis of control samples is done daily using
multilevel controls
i.e Low, normal and high level or using normal and
abnormal samples.

14. HEMATOLOGY ANALYSER –
SYSMEX
XN -1000

15. • XN CHECK is used as control blood for the quality
control of Sysmex X series instrument system.
• It includes stabilized human RBCs, human WBCs ,
platelet and nucleated red blood cell component in a
preservative medium.
• Once opened ,shelf life is 7 days. Storage – 2 -8 º C
• It provides parameters –
• Complete blood count
• White blood cell differentials
• Reticulocyte
• Nucleated RBCs

17. COAGULATION ANALYSER-
DESTINY PLUS

20. Control 2 is a lyophilized human plasma in which factors
2,7,9, and 10 have been selectively and partially removed
to get abnormal control in coagulation.

24. STATISTICAL METHODS FOR
ASSESSMENT
• Mean ( Target Value)
• Standard deviation (SD)
• Coefficient of Variation (CV)
• Levey Jennings chart
• Westgard rules
• Z Score

26. STANDARD DEVIATION
• It is an absolute measure of
dispersion.
• It measures how far a data point
lies from its mean .
• It is calculated for a single data
set.

28. • For example, sample – 2,3,4,5,6
• Mean = 2+3+4+5+6 =20/5 = 4
5
2-4=2 4 4+1+0+1+4=10
=√10/4
3-4=-1 1 5-1=4
4-4=0 0 SD= 1.58
~1.5
5-4=1 1
6-4=2 4

29. • 4+1SD 4+1X1.5= 5.5
• 4-1SD 4 -1X 1.5= 2.5
• 4+2SD 4+2X1.5 = 4+3= 7
• 4- 2SD 4- 2X1.5= 4-3=1

30. 1 2.5 4 5.5 7

31. LEVEY JENNINGS CHARTS
• These are statistics based control
charts to monitor quality control.
• The control values are plotted on
Y axis.
• The days of the month are plotted
on X axis.

38. WESTGARD RULES
• Westgard Rules are multiple QC rules to help
analyze whether or not an analytical run is in-
control or out-of-control.

39. SIX COMMONLY USED
WESTGARD RULES
• 12s
• One control measurement exceeding 2
standard deviations of control limits either
above or below the mean.
• This rule is used a warning rule to trigger
careful inspection of the control data.

41. • 13s
• A run is rejected when a single control
measurement exceeds the mean +3 control
limits.

43. • 22s
• The control run is rejected with 2 consecutive
control measurements ,2 standard deviations
on the same side of mean with this rule.

45. • R4s
• This rule rejects a run if two control
measurements in a group exceed the mean
with a 4 standard deviation difference
between the 2 controls.

47. • 41s
• This rule rejects a run with the 4th
consecutive control measurement exceeding
1 standard deviation on the same side of the
mean.

49. • 10x
• This rule rejects a control run when there are
10 consecutive controls on the same side of
the mean.

52. ERRORS ON L- J CHARTS
• Systematic errors
• Random errors
• Shifts
• Trends
• Dispersion

53. SYSTEMATIC ERRORS
• Errors that detect every test in a
constant, predictable manner.
For example –
• change in reagent lot number
• improper reagent preparation
• Incorrect storage conditions

54. RANDOM ERRORS
• Sudden control value of more than 2 SD
among acceptable control values.
• May occur 1 in every 20 analyses
• Precision is affected
• Causes –Temperature variation
• Bubbles in reagent
• Pipetting error
• Operator error

55. RANDOM ERROR

56. SHIFT
• Abrupt change in control values.
• Sudden fall on one side of the mean.
• Causes-
• Outdated controls and reagents
• Wrong controls,

58. TREND
• Change that occurs slowly over time.
• Progressive drifting from the mean.
• Causes- deteriorating agents.

60. DISPERSION
• Random control results.
• Wide scattering of values.
• Causes-
• Systemic failure
• Operator error

64. HEMATOLOGY ANALYSER
CLEANING AGENT

67. • According to NABL 112 , alternate methods of quality
control procedures are-
• Review of daily mean
• Delta check
• Clinical correlation
• Correlation with other laboratories ( Exchange of
samples with other accredited laboratories with
one functioning as reference laboratory.)

68. Storage of examined specimens according to
NABL 112
The examined specimens can be stored for re-examination for period
and temperature as specified below
• Complete Blood Counts: <24 hours at 2-80C
• Coagulation test: <4 hours at room temperature
The storage requirements for the samples which are retained for longer
period are as follows:
• i) Plasma can be stored at or below -20ºC for 1 week and -80ºC for
up to 1 year.
• ii) For PT up to 24 hours if samples are maintained between 18 -
24ºC and for heparin monitoring it shall be within an hour.
• Bone Marrow aspiration slides: 5 years
• Bone Marrow biopsy: 10 years

69. EXTERNAL OR INTER-
LABORATORY QUALITY CONTROL
• External quality assessment scheme (EQAS) or Proficiency
Test.
• Its based on analysis of control samples periodically by an
outside agency in order to compare accuracy levels of different
laboratories .
• Labs using the same reagents (peer group) are compared and
performance is reported in terms of Deviation index or Z Score.
• EQAS complements internal quality control and is a basic
requirement for laboratory certification and accreditation.

70. QUALITY CONTROL SAMPLES
Quality control samples obtained from the
manufacturer are usually manipulated to lengthen the
shelf life.
Therefore, direct comparison with patient results is not
possible.
Moreover, EQAS material should not be used for
calibration purposes.
There should be at least two specimens for every test.

71. PROFICIENCY TEST ITEMS
The programme must ensure that the items are:
• stable , safe and according to all relevant national
safety standards.
• negative for infectious agents (e.g. hepatitis B and C,
HIV in the case of human blood products)

72. • Agents such as antibiotics and antifungals or
preservative (sodium azide) can be used in
some specimens to reduce contamination.
•Vials should be leak-proof and made of
material usually plastic or glass, so that it does
not react .

73. • Those to whom delivery is expected to take longest,
should receive two or more panels .
• To return one panel unopened to the organizing centre
is requested .
• They then test the panel again to ensure that the
specimens have remained stable in twice the normal
period of transport.

74. HOMOGENEITY TEST
• Prior to preparation for distribution,
specimens should be tested to demonstrate
they have a consistent value within the
tolerance limits .
• And If specimens can be analysed in a
manner that will not destroy them during
testing.

75. Z SCORE
Z Score or standard score indicates how much
a given value differs from the standard
deviation.
It is the number of standard deviations a
given value is from the mean.
Z = x-µ ,where Z = standard or Z score
δ x= observed value
µ= mean of the sample
δ = standard deviation

77. • Z score 0: It happens rarely even with the most
competent lab .
• Z score between -2 to +2: is designated ‘acceptable’ or
‘satisfactory’.
• Z score outside range -3 to +3 regarded as
‘unsatisfactory’ or ‘not acceptable’.
• Z score between -2 to -3 and +2 to +3 of isolated event
are regarded as ‘questionable’.
• These criteria are stated in ISO/IEC standard
17043:2010

78. ISHTM-AIIMS-EQAP
• External quality control Programme is
organized by the Department of
Hematology, AIIMS New Delhi and Indian
Society of Hematology & Transfusion
Medicine (ISHTM).
• It is accredited by NABL (National
accreditation board for testing and
calibration laboratories.)

93. YOUDEN (XY) PLOT
• Two samples analysed and the results sample A
plotted on x axis and B on y axis.
• Lines then drawn demarcating the SD (or 2SD). The
results in the central block are satisfactory. Results in
top R (B) and bottom L blocks (A) indicate consistent
over or under readings . Results elsewhere indicate
random errors.

94. RESPONSE TO EQA REPORTS
• NABL 112 provides a simple approach –
• Clerical error – transcription error ( pre or post
analytical)
• Methodological problem
• Instrument function checks (e.g.,temperatures)
• Incorrect instrument calibration.
• Carry-over from previous specimen.
• QC material not run within expiration date
• Technical problem
• Sample not placed in proper order on instrument.

95. • Problem with proficiency testing materials
• Matrix effects: The performance of some
instrument may be affected by the matrix of the PT
sample. This can be overcome by assessing
participants in peer groups – to be done by the PT
provider.
• Problem with evaluation of results by the PT provider
• Incorrect data entry by PT provider.
No explanation after investigation – can be considered
random error.