Laboratory Activity 2 – Concepts of Quality Control and Safety in Serologic Testing Flashcards
The [?] of serologic test results are important in the correct diagnosis of diseases.
accuracy and reliability
There are various factors in the laboratory function that affect the outcome of serologic testing; these include
specimen collection and processing, methodology, test reagents/kits, instrumentation, technologist’s skills, and others.
To ensure the reliability of results, these factors must subscribe to the
standards of quality.
The exposure of the technologist to disease causing agents in the laboratory is of [?] concern.
primary health and safety
Possible [?] must, therefore, be known and well understood
risk factors
Refers to the overall process of guaranteeing quality patient care and is regulated throughout the total testing system
QUALITY ASSESSMENT or QUALITY ASSURANCE (QA)
are the variables that occur before the actual testing of the specimen
Pre-analytical factors
are the processes that directly affect the testing of specimens.
Analytical factors
Pre-analytical factors
• Test request
• Patient preparation
• Specimen collection, handling, and storage
Analytical factors
• Reagents
• Instrumentation and equipment: instrument calibration and maintenance
• Testing procedure
• Preventive maintenance
• Access to procedure manuals
• Competency of personnel performing the tests
Refers to the materials, procedures, and techniques that monitor the accuracy, precision, and reliability of a laboratory test
Quality Control (QC)
are performed to ensure that acceptable standards are met during the process of patient testing
QC procedures
Used to verify the accuracy and precision of a test and are exposed to the same conditions as the patient samples.
. External quality controls
(ability to obtain the expected result)
accuracy
(ability to obtain the same result on the same specimen)
precision
is the ability to maintain both precision and accuracy.
Reliability
consists of internal monitoring systems built into the test system
Internal quality control
monitor the correct addition of a patient specimen or reagent, the instruments/reagents interaction, and test completion
Internal or procedural controls
monitor a test system’s electronic or electric components
Electronic controls
• The testing of unknown samples received from an outside agency
• It provides unbiased validation of the quality of patient test results
Proficiency testing
are processes that affect the reporting of results and correct interpretation of data.
Post-analytical factors
How close measurement is to the true value
Accuracy
How close results are when the same sample is tested multiple times
Precision
Range of values over which laboratory can verify accuracy of a test system
Reportable range
Formerly called a normal value
Reference interval
Lowest concentration of a substance that can be detected by a test method
Analytical sensitivity
Ability of method to measure the only analyte it is supposed to measure and not other related substances
Analytical specificity
Process of testing and adjusting analyzer’s readout to establish a correlation between measured and actual concentrations
Calibration
Reference material with a known concentration of analyte
Calibrator
Testing materials of known concentrations (calibrators, controls, proficiency testing samples, patient specimens with known values) to ensure accuracy of results throughout reportable range
Calibration verification
Calibration verification
• Test three (3) levels:
high, midpoint, and low
Calibration verification
• Required every [?], when a lot number of reagents changes, following preventive maintenance or repair, and when controls are out of range
six months
Positive result in a patient who has the disease
o True Positive (TP)
Positive result in a patient who does not have the disease
o False Positive (FP)
Negative result in a patient who does not have
the disease
o True Negative (TN)
Negative result in a patient who has the disease
o False Negative (FN)
% of the population with the disease that tests positive
o Diagnostic sensitivity
% of the population without the disease that tests negative
o Diagnostic specificity
% of the time that a positive result is correct
o Positive predictive value (PPV)
% of the time that a negative result is correct
o Negative predictive value (NPV)
Other Components of the QA Program
o Correlation study
o Preventive maintenance
o Function checks
o Delta checks
Study to verify the accuracy of a new method
o Correlation study:
Schedule of maintenance to keep equipment in peak operating condition
o Preventive maintenance:
Procedures specified by the manufacturer to evaluate critical operating characteristics of a test system
o Function checks:
Comparison of patient data with previous results
o Delta checks:
Source: Infectious agents
Biological
Source: Needles, lancets, and broken glass
Sharp
Source: Preservatives and reagents
Chemical
Source: Equipment and radioisotopes
Radioactive
Source: Ungrounded or wet equipment and frayed cords
Electrical
Source: Bunsen burners and organic chemicals
Fire/explosive
Source: Slippery floors, heavy boxes, and patients
Physical
Possible Injury: Bacterial, fungal, viral or parasitic infections
Biological
Possible Injury: Cuts, punctures, or bloodborne pathogen exposure
Sharp
Possible Injury: Exposure to toxic carcinogenic or caustic agents
Chemical
Possible Injury: Radiation exposure
Radioactive
Possible Injury: Burns or shock
Electrical
Possible Injury: Burns or dismemberment
Fire/explosive
Possible Injury: Falls, sprains, and strains
Physical
Denotes infectious materials or agents that present a potential health risk
BIOHAZARD/Biological Health Hazard
Chain of infection and safety practices related to the biohazard symbol
BIOHAZARD/Biological Health Hazard
Concern over exposure to blood-borne pathogens resulted in the drafting of guidelines and regulations by the [?] and the [?] to prevent exposure.
Centers for Disease Control and Prevention (CDC)
Occupational Safety and Health Administration (OSHA)
The [?] describe four levels of biosafety depending upon the biological agents isolated or studied.
National Institutes of Health guidelines
The Biosafety levels are based on the [?] of the agents and the availability of effective [?]
virulence
treatments and vaccines
laboratories handle agents that have no known potential for infecting healthy people.
Biosafety Level 1
laboratories are those laboratories that work with microorganisms associated with human diseases that are rarely serious and for which preventive or therapeutic interventions are often available.
Biosafety Level 2
is recommended for materials that may contain viruses not normally encountered in a clinical laboratory and for the cultivation of mycobacteria. Working with mycobacteria requires the use of N95 HEPA filter respirators.
Biosafety Level 3
is required for work with dangerous and exotic agents that pose a high risk of aerosol-transmitted laboratory infections and life threatening disease for which effective treatments are limited.
Biosafety Level 4
Exposure risks
• Accidental punctures with needles
• Spraying (aerosols) or spilling infectious materials onto desktop or floor
• Cuts or scratches from a contaminated object
• Centrifuge accidents: aerosols, broken tubes, etc
all patients are considered to be possible carriers of blood-borne pathogens
Universal Precautions (UP)
The Universal Precautions (UP) recommends wearing [?] when collecting or handling blood and body fluids contaminated with blood and wearing [?] when there is a danger of blood splashing on mucous membranes and when disposing of all needles and sharp objects in puncture-resistant containers
gloves
face shields
The CDC excluded [?] not visibly contaminated by blood from UP, although many specimens can contain a considerable amount of blood before it becomes visible
urine and body fluids
guidelines are not limited to bloodborne pathogens; they consider all body fluids and moist body substances to be potentially infectious
Body Substance Isolation (BSI)
According to BSI guidelines, personnel should wear gloves at all times when encountering
moist body substances.
A significant disadvantage of BSI guidelines is that they do not recommend [?] following [?] unless visual contamination is present
handwashing
removal of gloves
Assume that everyone is potentially infected or colonized with an organism that can be transmitted in the healthcare setting
Standard Precaution
Includes guidelines describing personnel protective practices
Standard Precaution
- Requiring all employees to practice [?]
- UP/Standard Precautions
- Providing laboratory coats, gowns, face and respiratory protection, and gloves to employees and laundry facilities for[?]
- non-disposable protective clothing
- Providing sharps disposal containers and prohibiting [?] of needles
recapping
- Prohibiting eating, drinking, smoking, and applying cosmetics, lip balm, and contact lens in the
work area
- Labeling all [?] material and containers
biohazardous
- Providing free immunization for
HBV
- Establishing a [?] for work surfaces; an appropriate disinfectant for bloodborne pathogens is ____________________
daily disinfection protocol
- Providing [?] for employees who have been accidentally exposed to bloodborne pathogens
medical follow-up
- Documenting [?] in safety standards for employees
regular training
Any [?] to a possible blood-borne pathogen must be immediately reported
accidental exposure
Evaluation of the incident must begin right away to ensure appropriate
post-exposure prophylaxis (PEP)
Preventive measures are taken when a person is exposed to infectious disease
Post-exposure prophylaxis
Post-exposure prophylaxis Procedure:
1. Draw a baseline blood sample from the employee and test it for [?]
2. If possible, identify the source patient, collect a blood sample, and test it for HBV, HCV, and HIV. Patients must usually, give [?] for these tests, and they do not become part of the patient’s record.
3. Testing must be completed within [?] for maximum benefit from PEP.
- HBV, HCV, and HIV.
- informed consent
- 24 hours
General procedures/ policies that mandate measures to reduce or eliminate exposure to hazard
Work practice controls
Safety features built into the overall design of a product
Engineering controls
Work practice controls
o Hand washing after each patient contact
o Cleaning surfaces with disinfectants
o Avoiding unnecessary use of needles and sharps and not recapping
o Red bag waste disposal
o Immunization for hepatitis
o Job rotation to minimize repetitive tasks
o Orientation, training, and continuing education
o No eating, drinking, or smoking in the laboratory
o Warning signage
Engineering controls
o Puncture-resistant containers for disposal and transport of needles and sharps
o Safety needles that automatically retract after removal
o Biohazard bags
o Splash guards
o Volatile liquid carriers
o Centrifuge safety buckets
o Biological safety cabinets and fume hoods
o Mechanical pipetting devices
o Computer wrist/arm pads
o Sensor-controlled sinks or foot/knee/elbow-controlled faucets
Barriers that physically separate the user from a hazard
Personal protective equipment (PPE)
Personal protective equipment (PPE)
o Non-latex gloves
o Gowns and laboratory coats
o Masks, including particulate respirators
o Face shields
o Protective eyewear (goggles, safety glasses)
o Eyewash station
o Chemical-resistant gloves; subzero (freezer) gloves; thermal gloves
All biological waste, except urine, must be placed in appropriate containers labeled with the
biohazard symbol.
This includes both specimens and the materials with which the specimens come in contact
biological waste
The waste is then decontaminated following institutional policy:
incineration, autoclaving, or pickup by a certified hazardous waste company.
Disinfection of the countertops and sink using a [?] of sodium hypochlorite should be performed daily.
1:5 or 1:10 dilution
can be divided into three phases (i.e., pre-analytical, analytical, and post-analytical). These phases of the total testing process can be targeted individually for improving quality.
Laboratory practice
However, presence of [?] adversely affects the quality of the testing process.
laboratory errors
• Guideline describing personnel protective practices
Standard Precaution
o Present a serious biological hazard, particularly for the transmission of blood-borne pathogens
SHARP HAZARDS
Specimens that are POTENTIALLY infectious
o Blood
o Pus and purulent fluids
o Semen
o Vaginal secretions
o Cerebrospinal fluid
o Pleural fluid
o Peritoneal fluid
o Pericardial fluid
o Amniotic fluid
o Breast milk
Specimens that are usually NOT infectious (unless visibly bloody)
o Feces
o Nasal secretions
o Sputum
o Sweat
o Tears
o Urine
o Vomitus
is a law monitored and enforced by OSHA.
Occupational Exposure to Blood-Borne Pathogens Standard
Focus: Process; Defect Prevention
Quality Assessment
A pro-active process – avoiding errors before the actual process; prevention
Quality Assessment
o Should be appropriate and error free
o Job for the management
Quality Assessment
ALL THINGS ABOUT SAMPLE
PREPARATION
Pre-analytical factors
Test request
Patient preparation
Specimen collection, handling, and storage
Pre-analytical factors
indicating the days of testing for markers after exposure
Test kits with specifications
o Folded papers inside test kits; instructions
o Primary reference – from manufacturers
Package inserts
o Contains calibrating procedures
Package inserts
indicates a certain time before the detection of ABs and AGs
Package inserts
Reagents
Instrumentation and equipment: instrument calibration and maintenance
Testing procedure
Preventive maintenance
Access to procedure manuals
Competency of personnel performing the tests
Analytical factors
– detection of presence or absence of marker
Qualitative Tests
– determining concentrations of unknown; positive or reactive patients
Quantitative Tests
– Test for Analytical Sensitivity
Screening Tests
– Test for Analytical Specificity
Confirmatory Tests
Focus: Product or Results; Defect identification
Quality Control (QC)
A reactive process – defects identified are corrected
Quality Control (QC)
Should be high in order to avoid false negative reactions
Analytical sensitivity
Should be high in order to avoid false positive reactions
Analytical specificity
Formerly known as the STANDARD
Calibrator
– techniques or tests
Analytical
– results
Diagnostic
Delta checks are used for checking:
- Mixed up samples – wrong sample tested
- Technical errors – human or machine error; duplication of test to rule out problem
- Patient response to therapy – expected response is not achieved; may be due to changes on patient condition
most common biological agent among lab workers
Hepa B virus
viruses can survive in blood spills for
10 to 14 days
Establishing a daily disinfection protocol for work surfaces; an appropriate disinfectant for blood-borne pathogens is
5.25% NaCl in H2O (1:10)
10% common household bleach inactivates
o HBV for
o HIV for
o HBV for
o HIV for
10% common household bleach inactivates
o HBV for
o HIV for
o HBV for
o HIV for
10% common household bleach inactivates
o HBV for
o HIV for
o HBV for 10 mins
o HIV for 2 mins
