introduction of clinical laboratory science
TRANSCRIPT
TAPESHWAR YADAV(LECTURER)BMLT, DNHE,
M.SC. MEDICAL BIOCHEMISTRY
Clinical or Medical Laboratory
A – A good student is liked by teacher
G – Greets everyone with smileO – ObedientO – On time for collegeD – Dresses neatly
S – Studies with interestT – Treats everyone with smileU – Understands everythingD – Does daily home workE – Eager to know new thingsN – Never misbehavesT – Talks little in class
Introduction
Laboratory is a place that is equipped with different instruments, equipments and chemicals (reagents) etc., for performing experimental works, research activities and investigative procedures.
Medical laboratory is one part of the laboratory that is equipped with various biomedical instruments, equipments, materials and reagents (chemicals) for performing different laboratory investigative activities by using biological specimens (whole blood, serum, plasma, urine, stool, etc).
Medical laboratory science
Medical laboratory science is a complex field embracing a number of different disciplines such as:
Microbiology, Hematology, Clinical Chemistry, Urinalysis, Immunology, Serology,
Histopathology, Immunohematology and Molecular biology and others.
Contd…
Immunology, Serology, Histopathology, Immunohematology and Molecular biology and others.
Medical Laboratory Technology
The practice of modern medicine would be impossible without the tests performed in the clinical laboratory.
A medical team of pathologists, specialists, scientists, technologists, and technicians work together to determine the presence, extent, or absence of disease and provide data needed to evaluate the effectiveness of treatment.
Clinical or Medical Laboratory
Laboratories that perform chemical and microscopic tests on:
bloodother body fluidstissues
Clinical Laboratories
Play a major role in patient care Variety of settings Two types of Clinical.Laboratory
Hospital lab. Non hospital lab.
POLs Reference laboratories(LABCORP/QUEST D.) Government laboratories - federal
Center for Disease control and Prevention(CDC) Epidemiology labs Laboratory Response Network
Government Laboratories- state Premarital blood testing PKU testing in newborns Fungi,virus, and mycobacteria culture
Regulations of Clinical Laboratory
All laboratories, but research labs.are regulated by Federal and State agencies
CLIA’88- Clinical Laboratory Improvement Amendments of 1988:
Is a revision to the original CLIA of 1967, specifies the minimum performance standards for all Clinical Laboratories
Objectives of CLIA’88
To ensure quality Laboratory Testing, amendments are continually revised, updated, clarified and refined
CMS:Center for Medicare and Medicaid Services,agency within the Department of Health and Human Services responsible for implementing CLIA’88
CMS
Any Laboratory performing Lab. tests in humans ,except for research Labs. Must obtain a certificate from CMS (center for medicare-medicaid services) to be allowed to operate
Laboratory Personnel
Director of the Lab.- Pathologist, MD, DO, or hold a doctorate in a related clinical field. Hold certification and have supervisory and clinical laboratory experience
Technical supervisor/Lab.Manager-someone educated in the clinical laboratory sciences who has additional business experience
Laboratory personnel
General supervisor for each area Testing personnel:
Medical Technologists(MT/CLS) Medical Lab.Technicians(MLT/CLT) Medical assistants/nursing staff(POLs)
Departments of the Clinical Laboratory
Clinical Chemistry Hematology Microbiology Blood Bank Supports Services (Phlebotomy/Specimen
Processing)
Clinical Chemistry
Tests perform in serum, plasma, urine and other body fluids such as spinal fluid, or joint fluid
Largest department in the Lab. Toxicology Special chemistry
Hematology
Studying of the cellular components of the blood
Quantitative or Qualitative Coagulation Urinalysis Special hematology
Microbiology
Culture/identification microorganisms From sputum, wounds, blood, urine and other
body fluids Inoculated in culture media Organisms are identified and susceptibility
test are performed Bacteriology, virology, serology, parasitology
Blood Bank
Also called immunohematology or transfusion services
ABO group and Rh typing Antibody testing Storage of packed cells units Processing of some components like platelets
and cryoprecipitate
Support Services
Phlebotomists Accessioning
POCT
Point of care testing brings the laboratory to the patient, also called bed-side testing
Use small simple analyzers Portable instruments Hgb, glucose, electrolytes,and cholesterol
Quality Assessment System
QA.is incorporated to each department’s procedure manuals and day to day operation
Standardized material are analyzed on each instrument to document precision, and reproducibility
Calibration, maintenance and repair of the instruments is recorded
Participate in proficiency testing programs
Health care agencies have very specific standards, rules and regulations governing the education and job responsibilities of the laboratory personnel
Lab. professionals are required to complete an authorized program and certification
Lab. Personnel need to observe/protect patient privacy
Safety Occupational Safety and Health
Administration(OSHA) began in 1970 as a legislation and subsequent rules that mandate increased attention to safety in workplaces
The Clinical laboratory has, physical, chemical and biological hazards
PPE
Employees in the clinical lab are required to use personal protective equipment:
Gloves Mask Gowns
Biohazards
In 1980 clinical laboratory safety training concentrated in protection from chemical, physical,and contagious diseases such as tuberculosis
The discovery of AIDS, increased in Hepatitis B virus(HBV) and Hepatitis C virus(HCV) brought an emphasis on biological safety
The term Biohazard came into use A Biohazard symbol was adopted that
indicates the presence of biological hazard or biohazardous condition
Evolution on Biological safety
By 1960 infectious patients were placed in ISOLATION rooms
1970-CDC outlined isolation guidelines and listed isolation categories
1985-in response to the increasing AIDS/HIV epidemic CDC adopted Universal Blood and Body fluids precautions, to be applied in all patients regardless of their infectious status
1987- Body substance Isolation, included all body fluid even if not visibly contaminated with blood
Evolution on Biological safety
1991-OSHA issued “Bloodborne pathogens standard”, not included on previous regulation
1996- CDC implemented “Standard Precautions” that includes a comprehensive set of safety guidelines for Health care workers rendering care to patients, this is the current terminology
To control nosocomial (inst. acquired) infections Transmission-based precautions(additional practices for pathogens
that spread by air, droplets, and contact 2001-OSHA revised the BBP(blood borne pathogen)
standard to prevent accidental needle-sticks in the workplace
Standard PrecautionsRequires that every patient and every body
fluid, body substance, organ, or unfixed tissue be regarded as potentially infectious Hands wash(plain soap)
After touching body fluids and contaminated items, after removing gloves and between patient contact
Wear gloves When touching blood/body fluids/secretions, wear clean
gloves when touching mucous membranes and nonintact skin
Wear mask/eye protection/face shield Activities that could generate splashes, spray of blood,
body fluids , or secretions
Standard Precautions, cont.Patient care equipment
should be handled to prevent transfer of microorganisms to other patients and environment
Linen Handle, transport,and process in a manner to avoid
contamination of clothing and other patients or environment
Occupational health and blood-borne pathogens Prevent injuries when using, handling, cleaning and
disposing sharps NEVER RECAP A USED NEEDLE Do not removed used needle from syringe by hand Disposed used sharps on puncture resistant
containers
Standard Precautions,cont.
Use resuscitation devices as an alternative to mouth to mouth resuscitation
Patient placement Use a private room for patients who can be a
source of contamination or patients who are not expected to maintain hygiene or environmental control
Environmental control Follow hospital procedures for routine care and
cleaning/desinfection of any soiled device, equipment or environmental surface
General laboratory equipment
Centrifuges- spin samples at high speeds forcing the heavier particles to the bottom of the container,e.g..separating plasma and blood cells Safety tips
Use Standard Precautions/PPE Load must be balanced Tubes must be capped during operation Do not open the centrifuge while rotor is moving Clean spills immediately with surface disinfectants
General laboratory equipment
Autoclaves- use steam under pressure to sterilize medical/surgical instruments, or contaminated materials before disposal Never open unless the chamber pressure reads
zero Use heat-proof gloves to remove items When sterilizing liquids use loosely capped, heat
resistant containers, no more than half full Use an autoclave tray to prevent liquids from
spilling
General laboratory equipment
Laboratory balances Used to measure chemicals Use PPE and chemical safety precautions Be gentle, Balances are delicate equipment
General laboratory equipment
Other equipments Refrigerators Water baths PH meters Incubators Thermometers freezer
The Microscope
Is a delicate and expensive instrument , special care must be taken in its use
Various types of microscopes, two categories based on type of illumination Light microscopes
Bright-field- stained specimens Phase-contrast-unstained cells,urine sediment Epi-fluorescence microscope,specimens treated with
fluorescent dyes, syphilis, mycobacteria Electron microscopes:provides greater
magnification in medical research
Light microscope images
A-stained cell seen with bright field microscopeB-phase contrast imageC-epi-fluorescence microscopy,Borrelia burgdorferi
Parts of the Microscope
Parts of the Microscope
Oculars: monocular or binocularObjective lenses: attached to the revolving
nose piece, at least 3 present: low, high dry, and oil immersion lenses
Light condenser which focuses and directs light to the objectives, iris diaphragm that regulates the amount of light that strikes the object observed
Field diaphragm:help align the lightCoarse and fine adjustments:focusing knobsStage:support for the object been viewed
Microscope safety Safety
observe electrical safety rules Glass slide handle with care to avoid breaking Unfixed specimens should be treated with standard
precautions,disinfect stage after use QA
Scheduled maintenance should be performed and documented
Care and cleaning of lenses Use only lens paper, clean lenses before and after
each use Do not allowed immersion oil to touch the low and
high dry lenses Transporting and storing
Transporting the Microscope
Using the Microscope
Use low power objective to locate and to view large objects
With the coarse adjustment knob bring the objective and the slide as close together as possible
While looking through the oculars, move the coarse adjustment knob to bring the objective and slide apart until the object on the slide comes into focus
Use the fine adj.knob to bring the image into sharp focus
Using the Microscope If you need to use the high power(40x), to see
cells and sediments, after initial focusing with the low power(20x), rotate the high power into position
Never use the coarse adjustment knob with high power, the distance between the objective and slide is very small and the slide could break.
Oil immersion lenses(100x) give the highest magnification of the bright field objectives
Using oil immersion lenses After initially focusing with the low power,
rotate the objective to the side and place a small drop of immersion oil on the slide
The oil immersion objective is rotated into the drop of oil been careful no other objective touch the oil
use only fine adjustment knob with oil Condenser should be all the way up Maximum light source Open the iris diaphragm to the
maximum
After using the Microscope
Always switch to the low magnification objective
With lens paper clean the oil immersion objective, stage and condenser if oil has become in contact with it
Turn the light source off Unplug the microscope Store in proper location or cover as
appropriate
Calculate Magnification
Degree of magnification on the ocular multiplied by the degree of magnification on the objectives
Example:10x(ocular) x 100x(oil immersion)= 1000x
The object viewed would be magnified 1000 times its original size Resolving power: the ability of a microscope
to produce separate images of closely spaced details in the object being viewed
Blood collection
Capillary puncture: small amount of blood collected for glucose, K, electrolytes, Hgb, Htc, Plt count, or when a larger sample is difficult to obtain as in newborns
Routine venipuncture: most common method of obtaining blood, a superficial vein is punctured with a hypodermic needle and blood is collected into a syringe or vacuum tube
Capillary Puncture Safe Quick Small amount of blood Increased use
Point-of-care testing (POCT) Physician Office Laboratories
Capillary Puncture Sites
Fingertip Great toe Heel
Capillary Puncture Sites
Lancets
Sterile Single-use Different lengths
Collection Containers
Procedure
Routine Venipuncture
Phlebotomy Superficial vein Large sample of blood Skill and experience
Preserve vein integrity
Venipuncture Supplies
Needles Various safety designs 21 ga, 1 inch
Needle holders Phlebotomy tray
Venipuncture Supplies
Venipuncture Supplies
Vacuum tubes and anticoagulants Sizes Stopper color:
Red: no anticoagulant, to collect serum for blood chemistries and serology tests
Lavender: containing EDTA for hematologycal and blood typing tests(ethylenediaminetetraacetic acid )
Green: contains heparin, for lymphocytes studies and special chemistry
Light blue: sodium citrate for coagulation studies Gray :potasium oxalate, for glucose and legal alcohol Black: for westergren ESR
Draw exact amount
Safety Precautions
Observe standard precautions Wear gloves and other PPE Never recap needles Use proper technique
Avoid Hemoconcentration: do not leave tourniquet in
place for more than 1-2 minutes Hemolysis: do not shake tubes, mix by gently
inverting a few times
Select Equipment
Patient Preparation
Patient I.D. Explain procedure Support patient and arm Be prepared! for any sudden reaction from
the patient, or occasional patient who may faint
Patient Preparation
Apply Tourniquet
•3-4 inches above elbow•Use quick release tie
Identify Suitable Vein Veins commonly used
Median cubital Basilic Cephalic
Palpate vein: carefully inspect both arms to find the better site
Perform Venipuncture Alcohol-cleanse site, let air dry, do not
touch the site after cleaning Observe bevel up Anchor vein with thumb 1inch below the
puncture site Enter vein in the same direction of it, in
a15-25 degree angle, in a smooth motion Insert vacuum tube
Clot tube first Invert anticoagulant tubes softly 5-7 times
Perform Venipuncture
Adverse situations In case of patient developing a large hematoma
while venipuncture procedure is being done, withdraw the needle, apply pressure, and intent the procedure in a different site
In case of failure to obtain the blood, ask the patient permission for a second intent, if he agrees try in a different site
After the second non-productive intent,inform the patient and find another person to draw the specimen
Complete Procedure
Activate safety feature Immediate disposal Label tubes before leaving the room Patient care
Patient care
The tourniquet is always release before needle is withdraw
Gauze should be applied over the puncture site and pressure maintained for 1-3 minutes or until bleeding stops
Ask patient to keep arm extended Offer a small bandage if necessary
In Case of Accident
Immediately clean exposed area Flood with water Clean with antiseptic soap
Report immediately to supervisor Seek medical attention
Label the samples
Must contain patient information Name Date of birth
Date and time of collection And initials of the person drawing the blood Tubes should never be prelabeled to avoid using
the prelabeled tube in the wrong patient Make sure the tubes are clean and no blood has
contaminated the outer part of the tubes Place specimen in a biohazard labeled bag and
proceed as required by the institution
selecting tests to use:
Test selections are based on : subjective clinical judgment, national recommendations, and evidence-based health care. Often diagnostic tests or procedures are used as
predictors of surgical risk or morbidity and mortality rates because, in some cases, the risk may outweigh the benefit.
selecting tests to use:
1.Basic screening (frequently used with wellness groups and case finding)
2. Establishing (initial) diagnoses3. Differential diagnosis4. Evaluating current medical case
management and outcomes 5. Evaluating disease severity
6. Monitoring course of illness and response to treatment
7. Group and panel testing 8. Regularly scheduled screening tests as part
of ongoing care 9. Testing related to specific events, certain
signs and symptoms, or other exceptional situations (eg, infection and inflammation , sexual assault, drug screening, postmortem tests, to name a few)
Basic screening (frequently used with wellness groups and case finding)
Cervical Papanicolaou (Pap) test Yearly for all women 18 years of age; more
often with high-risk factors (eg, dysplasia, human immunodeficiency virus [HIV], herpes simplex); check for human papillomavirus (HPV), chlamydia, and gonorrhea using DNA
Establishing (initial) diagnoses
Serum amylase In the presence of abdominal pain, suspect
pancreatitis Thyroid-stimulating hormone (TSH) test
Suspicion of hypothyroidism, hyperthyroidism, or thyroid dysfunction in patients 50 years of age
Differential diagnosis
Chlamydia and gonorrhea In sexually active persons with multiple partners;
monitor for pelvic inflammatory disease
Evaluating current medical case management and outcomes
Tuberculosis (TB) blood test QuantiFERON Gold TB Blood test to assess TB exposure in risk population
Syphilis serum fluorescent treponemal antibody (FTA) test Positive rapid plasma reagin (RPR) test result
Grading Guidelines for Scientific Evidence
A. Clear evidence from all appropriately conducted trials Measure plasma glucose through an accredited lab to
diagnose or screen for diabetes B.Supportive evidence from well-conducted
studies or registries Draw fasting blood plasma specimens for glucose
analysis
C.No published evidence; or only case, observational, or historical evidence • Self-monitoring of blood glucose may help to
achieve better control E.Expert consensus or clinical experience
or Internet polls Measure ketones in urine or blood to monitor and
diagnose diabetic ketoacidosis (DKA) (in home or clinic)
The diagnostic testing model
incorporates three phases: pretest,
emphasis on appropriate test selection, obtaining proper consent, proper patient preparation, individualized patient education, emotional support, and effective communication. These interventions are key to achieving the desired
outcomes and preventing misunderstandings and errors.
Intratest Phase: Elements of Safe, Effective, Informed Care
Posttest Phase: Elements of Safe, Effective, Informed Care
The clinical value of a test is related to
sensitivity, specificity, and the incidence of the disease in the population tested.
Sensitivity and specificity do not change with different populations of ill and healthy patients
The predictive value of the same test can vary significantly with age, gender, and geographic location.
Specificity refers to the ability of a test to identify correctly those individuals who do not have the disease.
The division formula for specificity is as follows:
Specificity%=persons w/o dis.who test neg./total # of persons w/o dis. X 100
Sensitivity refers to the ability of a test to correctly identify those individuals who truly have the disease.
The division formula for sensitivity is as follows:
Sensitivity% = persons with dis.who test positive/ total # persons tested with disease x 100
Incidence refers to the number of new cases of a disease, during a specified period of time, in a specified population or community.
Prevalence refers to the number of existing cases of a disease, at a specific period of time, in a given population.
Predictive values
Predictive values refer to the ability of a screening test result to correctly identify the disease state.
The predictive value of the same test can be very different when applied to people of differing ages, gender, geographic locations, and cultures.
test outcome deviations
Minimize test outcome deviations following proper test protocols. Make certain the patient and his or her significant
others know what is expected of them. Written instructions are very helpful.
Reasons for deviations may include the following
Incorrect specimen collection, handling, storage, or labeling
Wrong preservative or lack of preservative Delayed specimen deliver
Reasons for deviations may include the following
Incorrect or incomplete patient preparation Hemolyzed blood samples Incomplete sample collection, especially of
timed samples Old or deteriorating specimens
Patient factors that can alter test results may include the following
Incorrect pretest diet Current drug therapy Type of illness. Dehydration Position or activity at time of specimen
collection
Patient factors that can alter test results may include the following
Postprandial status (ie, time patient last ate)
Time of day Pregnancy Age and Gender
Patient factors that can alter test results may include the following
Level of patient knowledge and understanding of testing process
Stress Nonadherence or noncompliance with
instructions and pretest preparation Undisclosed drug or alcohol use
avoid costly mistakes
Communication errors account for more incorrect results than do technical errors.
Properly identify and label every specimen as soon as it is obtained.
Educate the patient and family
Educate regarding the testing process and what will be expected
Record the date, time, type of teaching, information given, and person to whom the information was given.
Educate the patient and family
Giving sensory and objective information that relates to what the patient will likely physically feel and the equipment that will be used is important so that patients can envision a realistic representation of what will occur.
Educate the patient and family
Avoid technical and medical jargon and adapt information to the patient's level of
understanding. Slang terms may be necessary to get a point
across.
Educate the patient and family
Encourage questions and verbalization of feelings, fears, and concerns
Do not dismiss, minimize, or invalidate the patient's anxiety
Develop listening skills, and be aware of nonverbal signals (ie, body language)
Educate the patient and family
Above all, be nonjudgmental. Emphasize that there is usually a waiting
period (ie, turn-around time) before test results are relayed back to the clinicians and nursing unit.
Offer listening, presence, and support during this time of great concern and anxiety
Educate the patient and family
Because of factors such as anxiety, language barriers, and physical or emotional impairments, the patient may not fully understand and assimilate instructions and explanations
Educate the patient and family
To validate the patient's understanding of what is presented, ask the patient to repeat instructions given to evaluate assimilation and understanding of presented information.
normal or reference values
Normal values are those that fall within 2 standard deviations (ie, random variation) of the mean value for the normal population.
Normal ranges can vary to some degree from laboratory to laboratory. Frequently, this is because of the particular type of equipment used
normal or reference values
The reported reference range for a test can vary according to the laboratory used, the method employed, the population tested, and methods of specimen collection and preservation.
normal or reference values
Interpretation of laboratory results must always be in the context of the patient's state of being.
Circumstances such as hydration, nutrition, fasting state, mental status, or compliance with test protocols are only a few of the situations that can influence test outcomes.
clinical laboratory data values
may be reported in conventional units, SI units(Systéme International (SI) units), or both
The SI system uses seven dimensionally independent units of measurement to provide logical and consistent measurements
clinical laboratory data values
SI concentrations are written as amount per volume (moles or millimoles per liter)
rather than as mass per volume (grams, milligrams, or milliequivalents per deciliter, 100 milliliters, or liter)
Numerical values may differ between systems or may be the same.
For example, chloride is the same in both systems: 95 to 105 mEq/L (conventional)
and 95 to 105 mmol/L (SI).
Recognize margins of error
possibility exists that some tests will be abnormal owing purely to chance
because a significant margin of error arises from the arbitrary setting of limits.
Moreover, if a laboratory test is considered normal up to the 95th percentile, then 5 times out of 100, the test will show an abnormality even though a patient is not ill
Cultural Sensitivity
Many cultures have diverse beliefs about diagnostic testing that requires blood sampling
Preserving the cultural well-being of any individual or group promotes compliance with testing and easier recovery from routine as well as more invasive and complex procedures
END