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Clinical Chemistry > Method Evaluation and Quality Control > Flashcards

Method Evaluation and Quality Control Flashcards

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1
Q

Identify source of analytic variability:

(1) experiments must be redone when blackout happens

A

power surges

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2
Q

Identify source of analytic variability:
(2) temperature and humidity being kept constant as to why specimens and experiments are in a very controlled environment

A

environmental conditons

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3
Q

Identify source of analytic variability:

(3) presence or absence of staining in 0.1 antibody may be caused by contaminated buffer solution

A

contamination

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4
Q

Identify source of analytic variability:

(4) the medical technologist used the wrong speciment on the CBC test machine

A

operator technique

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5
Q

Identify source of analytic variability:

(5) 3 Tesla MRI produces clearer image and abnormalities are detected faster than 0.3 Tesla MRI

A

Instrument differences

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6
Q

Identify source of analytic variability:
(6) external features causing abnormal findings due to hemolysis, lipemia, serum proteins, specimen sitting too long or not properly centrifuged.

A

Matrix effects

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7
Q

Identify source of analytic variability:
(7) two operators reading the EEG on different time scale in same instrument, one may look at it differently than the other.

A

Operator technique

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8
Q

Other sources of analytic variability:

A

Reagents

Test accessories

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9
Q

An all-inclusive, comprehensive system monitoring the accuracy of test results where all steps before, during and after the testing process are considered which includes pre-analytic, analytic and post-analytic factors

A

Quality Assurance/Assessment

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10
Q

Essentials for quality assurance

A

Commitment to quality
facilities, resources, competent staff
reliable procedures, methods, instrumentation

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11
Q

Quality assurance provides what?

A

a structure for achieving lab and hospital quality goals

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12
Q

These systems monitor the analytical process, detects and minimize errors during analysis thus preventing reporting of erroneous test results

A

Quality Control

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13
Q

Quality control requires following published rules such as?

A

Westgard rules (accompanied by Levy-Jennings chart)

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14
Q

Type of QC done daily and serves as establishment of reference ranges and validation of new reagent lot and/or shipment. It is done following instrument repair

A

Internal

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15
Q

type of QC which involves proficiency testing wherein laboratory testing performances are determined via interlaboratory comparisons

A

external

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16
Q

It is integrated within routine workload and analyzed by personnel who are running the test. It is an ongoing evaluation of results to correct unacceptable results and assess employee competency

A

Proficiency testing

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17
Q

Pre-Analytical and Analytical causes of error

A

samples
operators
reagents (degradation, QC material degrad., calibrator d.)
laboratory environment (atmospheric environment: dust, temp., humidity; utility e.: electircal, H20 quality, pressure)
measuring system (instrument failure: software, optics drift, electronic instability)

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18
Q

Some post-analytical sources of error

A

incorrect reference values
physician not notified of a panic or critical value
incorrect interpretation of lab results by physician
incorrect data entry of lab results

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19
Q

some errors involved in sample presentation and integrity

A

integrity: lipemia, hemolysis, interfering substances, clotting factors, incorrect tube
presentation: bubbles and inadequate volume

20
Q

some errors involved in operator capacity and staffing

A

capacity: training, competency (wrong use of machines +insufficient reagents)
staffing: short staffing, correct staffing

21
Q

A statistical analysis of lab test data helps define:

A

Reference ranges for patients

Acceptable ranges for control specimens

22
Q

statistical concept wherein all values are symmetrically distributed around the mean and has the characteristic bell-shaped curve. It is also assumed for all quality control statistics

A

Gaussian/Normal Distribution

23
Q

What determines accuracy and precision in Gaussian distribution?

A

accuracy: mean of curve at center of curve
precision: data is grouped together as represented by a well-rounded bell curve

24
Q

What does a curve signify if its center is off the mean?

A

Low accuracy due to systematic error

25
Q

What does a curve signify if it is spread out resulting in a flatter curve?

A

low precision due to random errors

26
Q

What is an error?

A

difference between test and reference method results

27
Q

type of error which is:

  • present in all measurements
  • can be either positive or negative
  • can be a result of many factors including instrument, operator dependence, reagent and environmental variations
  • an imprecision of the test system causing scattered control values around the mean
A

Random error

28
Q

What are the causes of random error?

A 
air bubbles in reagent
improperly mixed reagents
reagent lines, sampling, reagent syringes
improperly fitting pipette tips
clogged or imprecise pipettor
fluctuations in power supply
29
Q

type of error which:

  • influences observation consistently in one direction
  • can be further broken down into constant and proportional
  • displacement of mean from original value
  • predictable and causes shifts or trends in contorl charts
A

systemic error

30
Q

What are the causes of systemic error?

A
  • change in reagent or calibrator lot numbers
  • wrong calibrator values
  • improperly prepared reagents
  • deterioration of reagents or calibrators
  • inappropriate storage of reagents or calibrators
  • variation in sample or reagent volumes due to pipetter misalignments
  • variation in temperature or reaction chambers
  • deterioration of photometric light source
  • variation in procedure between technologists
31
Q

It is the amount by which an analysis varies from the correct result (ie: expected: 50, result: 47, bias =3)

A

bias

32
Q

it is a mathematical expression of a group of data around a mean

A

standard deviation

33
Q

It indicates what percentage of the mean is represented by the standard deviation. It is also a reliable means for comparing the precision or SD at different units or concentration levels expressed as %.

A

coefficient of variation

34
Q

T or F: the larger the CV, the less reproducible the results are (less values closer to mean)

A

True

35
Q

How many levels of control material are used to establish a QC system?

A

2-3

36
Q

It is the material or preparation used to monitor the stability of the test system, within predetermined limits

A

Control

37
Q

the purpose of establishing a QC system is ??

A

to verify the analytic measurement range of the instrument for a specific analyte

38
Q

It is when QC data results are distributed on one side of the mean for 6-7 consecutive days

A

shift

39
Q

It is when there is consistent increase or decrease of QC data points over a period of 6-7 days

A

trend

40
Q

What is the corrective action for technical errors?

A

identify error and repeat test

41
Q

It is the range of analyte values that a method can directly measure on the specimen without any dilution, concentration or other pretreatment

A

Analytical Measurement Range

42
Q

It is the range of analyte values that a method can report as a quantitative result, allowing for specimen dilution, concentration, or another pretreatment used to expand the direct AMR

A

Clinical reportable range

43
Q

system flag for comparison of individual patient results throughout the day or week with computer detection of changes from earlier individual patienr results and helpful to identify pre-analytic errors

A

Delta check (see trans)

44
Q

It is the normal or expected value for patients defined as being within +/- 2SD from the mean (based on local population by lab)

A

Reference ranges (see factors affecting this)

45
Q

values that indicate a life-threatening situation for the patient. They require notification of the value to nurse or physician which must read back results to technician

A

critical values and read back of results (see trans)

Clinical Chemistry (9 decks)

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