specimen handling and processing Flashcards
what are the 3 phases of laboratory process
Pre-examination / Pre-analytical
- prior to testing
Examination / Analytical
- during testing
Post-examination / Post-analytical
- after testing
who use the term “examination” instead of “analytical” when referring to the process of testing clinical samples.
the CLSI Quality Management System, QMS
where does most laboratory errors occur
pre examination phase
- begins when a patient is assessed and test is ordered
- 50-70% lab errors
true or false:
storage after testing is part of the post examination phase but can become part of the pre examination phase
true - when repeat testing or additional tests are ordered on a specimen, sometimes hours or even days later
what are the possible source of preexamination/ preanalytical error before collection
altitude
dehydrated patients
duplicate test orders
exercise/ strenuous exercise
treatments (intravenous medicine etc)
inadequate fast
incomplete requisition
medications
stress
pregnancy
smoking
wrong test ordered
what are the possible source of preexamination/ preanalytical error at time of collection
misidentified patient
antiseptic not dry
expired tube
failure to invert additive tubes properly
faulty technique
improper vein selection
inadequate vol. of lood
inappropriate use of PST or SST
incorrect
- collection tube
- needle position
- needle size
mislabeled tube
mixing tubes too vigorously
nonsterile site preparation
patient position
prolonged tourniquet application
underfilled tube
wrong collection time
what are the possible source of preexamination/ preanalytical error during specimen transport
agitation-induced hemolysis
delay in transporting
exposure to light
failure to follow temp requirements
transport method (hand vs pneumatic tube)
what are the possible source of preexamination/ preanalytical error during specimen processing
contamination (dust or glove powder etc)
delay in processing or testing
delay in fluid separation from cells
evaporation
failure to centrifuge specimen according to test requirements
failure to separate fluid from cells
what are the possible source of preexamination/ preanalytical error during specimen storage
exposure to light
temp change outside defined limits
what is specimen handing
refers to the processed involved in the:
collection
transport
processing
storage of biological specimens
what are the collection procedures
Specimens must be collected using aseptic techniques to prevent contamination.
The choice of collection tubes (e.g. anticoagulants) should align with the type of test being performed.
Timely collection is essential; specimens should be drawn at specific times as required by certain tests.
according to CLSI, what type of tubes should be placed in an upright/ vertical with the stopper up position as soon as they have been mixed and why
Nonanticoaugulant gel tube
to prevent agitation-induced hemolysis: (RBC damage and activate platelets )
what happens if there is a delay in separating the blood cells from the plasma or serum
can reult in metabolic changes in the sample (pertaining to metabolism)
according to CLSI, why should tubes be transported vertically with stopper up
upright position:
- reduce agitation that can cause RBC damage - lead to hemolysis in the specimen
- allows blood too drain away from the tube stopper to minimize the chance od aerosol (a fine mist of specimen) release when the stopper is removed
- aids clot formation in serum tubes
- prevent the clot from sticking to the stopper
what are the CLSI and OSHA guideline to place the blood specimen tubes
biohazard bag or container with a biohazard logo, liquid tight closure and slip pocket for requisition.
- The size of the bag is not standard. Depends on the order of the laboratory.
what are the CLSI and OSHA guideline to place nonblood specimens
should be leak proof containers with secure lids.
- should be tightly sealed in a cooler box.
Most common means of transporting specimens to the lab from other areas of the hospital.
Pneumatic Tube System (PTS)/ Vertical Track System
- aka PTS/ p-tube
(Automated Internal Transportation Systems)
Consists of a network of long tubes that connect to sending and receiving stations in certain lab arrears to various sections of hospitals.
Pneumatic Tube System (PTS)/ Vertical Track System
- aka PTS/ p-tube
For example:
Will be passed from sending station (e.g.nurse station) to receiving station (e.g microbiology, hematology lab)
- considered biohazard & require strict protocol to prevent potential contamination issues
-packed in leak-resistant containers and sealed in zipper-type plastic bags to contain spills
who hand delivered the blood specimens on onsite transportation of specimens
By the phlebotomist or other healthcare worker who collected blood specimens.
- Post graduate intern
- Nurses
what are the test tat are negatively affected and not affected by the PTS transport
negatively:
potassium
acid phosphate
plasma hemoglobin
lactate dehydrogenase
maintain at room temp - cryoglobulin & cold agglutinin
not affected:
albumin
alkaline phosphatase
AST
chloride
creatinine
glucose
sodium
total bilirubin
total protein
BUN
uric acid
thrombin time
WBC conc.
Involved an autonomous mobile robots (AMR)
Robot system
- Able to navigate through the facility to transport the lab specimen
what are some off-site transportation of specimens
physician offices
clinics
patient services centers
private homes
those locations^ or healthcare facility laboratories to local or regional reference laboratories
in Local Courier or Mobile Phlebotomist, how should the specimen be transported
in a leakproof of primary container/ blood tube and put it in a zip-closure plastic bag with an absorbent material (paper towels etc) and placed it in a secondary container using a plastic or metal cooler transport box. (can use Styrofoam box too)
- placed upright in a rack that sits on top of the absorbent material in the bottom of the transport box (shld be closed to avoid spills n contamination)
Out-of-Area Transportation
diagnostic specimens (blood, urine, tissue samples) that are transported out of the area by public transportation (commercial airlines, buses, trains)
what are the safety rules that must be followed in Out-of-Area Transportation
Covered by U.S
Department of Transportation (DOT)
International Air Transport Association (IATA)
regulations for transportation of infectious substances.
what are the 2 categories of infectious substances
Biological Substance Category A
- Capable of causing permanent disability or life-threatening or fatal disease in normally healthy humans
- normally healthy humans: UN 2814
- animals: UN2900
Biological Substance Category B
- Infectious substances DOES NOT meet the criteria for Category A
- UN 3373
- Lab specimens for transported for diagnostic purposes
what are the category B regulations require triple packaging requirements
what are the minimum required markings for the outer packaging container
UN 3373 label with the words “Biological Substances Category B”
Serum or plasma should be physically separated from the cells as soon as possible unless evidence is conclusive that a longer contact time will not contribute to error in test results.
CLSI Guideline GP44-A4
- on time limits
this recommends a time limit of less than 2 hours for separating serum or plasma from the cells for the following
[These specific tests MUST have the blood separated within 2 hours of collection]
Catecholamines (stress hormones)
Homocysteine (amino acid)
Lactic acid (muscle byproduc)
HIV-1 assay
LDH (enzyme test)
HBV assay
Glucose (blood sugar)
Ionized calcium
Potassium
[If blood sits too long before separation, the cells can affect the test results
This can lead to false high or low readings
Some substances in blood change quickly over time if not properly processed]
according to a 2013 article in the journal environmental and public health, how does the results of community outreach studies found that glycolysis by erythrocytes and leukocytes in blood specimen
falsely lower glucose values from 5 to 7% per hr
what is the recommended time for separating serum and plasma from the cells
a time limit of less than 2 hours
Special care is needed when handling blood specimens to protect its condition and quality.
special handling
what are the types of special handling
Body temperature specimens:
- cold agglutinin, cryofibrinogen, cryoglobulin
Chilled specimens:
- Chilling slows down the blood cell metabolite process
- Protects thermolabile (breaks down or becomes unstable when exposed to heat) analytes.
Specimens that must not be chilled:
1. coagulation specimen
Can activate clotting factors
Disrupt platelet function
- potassium
Inhibit glycolysis - pumps potassium to the cells. Hence, the potassium levels will elevate.
Light-sensitive specimens:
- Photosensitive analytes result in falsely decreased results.
- wrapped in aluminum foil to protect it from light and an amber of aliquot or transport tube
body temp:
room temp:
refrigerated temp:
frozen temp:
body temp:
36.4 to 37.6°C (37°C average)
96.8 to 99.7°F (98.6°F average)
room temp:
20 to 30°C (25°C average)
68 to 86°F (77°F average)
refrigerated temp:
2 to 10°C
35.6 to 50°F
frozen temp:
-20°C or lower (some specimens require -70°C or lower)
-4°F or lower (some specimens require -94°F or lower)
expression “on ice”
describe how a specimen shld be transported
what it rlly means is the specimen requires chilling and shld be transported in an ice slurry or cooling rack
examples of speciimens that require special handling
ACTH, adrenocorticotropic hormone
ammonia
catecholamines
gastrin
homocysteine (red top): ice slurry OK
homocysteine (gel tube): cooler rack only
lactic acid
metanephrines, plasma
PTH, parathyroid hormone
pyruvate
examples of specimens that require special handling: protect from light
beta-carotene
bilirubin
folate
Vitamin A, B2, B6, C
urine porphobilinogen
urine porphyrins
CLSI Standard C46-A2
recommends that ABG samples should NOT be placed on ice if analyzed within 30 minutes.
true or false:
if a potassium test is ordered with other analytes that require chilling, it should be collected in a separate tube
true
STAT or medical emergency specimens should be transported, processed and tested immediately.
Time Limit Exceptions
- ammonia specimens
- coagulation specimens
- glucose specimens in sodium fluoride tubes
- pediatric glucose specimens
- hematology specimens
- molecular test specimens
- microbiology specimens
- urine specimens
at what temperature does the ammonia increases
at room temperature
hence, must immediately placed in an ice slurry or cooling tray after collection.
* transported STAT
* separate from cells by centrifugation within 15min of collection
what test are processed ASAP afer collection
plasma-based coagulation test (coagulation test)
prothrombin time, PT vs PTT
glucose specimens in sodium fluoride tubes
room temp: up to 24hrs
refrigerated (4-8°C): up to 48hrs
Complete inhibition of glycolysis can take as long as 4 hours.
[It takes up to 4 hours for the sodium fluoride (preservative) to fully stop glycolysis
Glycolysis = the process where glucose gets broken down in the blood sample]
If more than 4 hours before testing - glucose levels can fall as much as 10 mg per deciliter.
whose specimens are difficult to inhibit glycolysis.
Newborns and pediatric
- Small tubes (microcollection tubes) are used because babies and children have less blood to give
- These tubes contain chemicals (antiglycolytic agents) to stop glucose from breaking down
why is Inhibition of glycolysis may be inadequate with patients with abnormally high platelets, RBC or WBC count.
as there are too many cells in the blood (hungry ppl) that breaks down glucose (sugar) in the blood
= glucose readings might be falsely loe - too many cells ate up the glucose before the test could be done, even with preservative present
hematology specimens
EDTA tubes (blood smear):
CBC:
ESR:
Reticulocyte count:
EDTA tubes (blood smear):
must be prepared within 1 hr after collection
to preserve integrity of RBCs (keep rbc looking normal)
prevent artifact formation (false formation in cells that cld lead to wrong diagnosis)
CBC:
EDTA blood specimens shld be analyzed within 6 hrs
generally stable for 24 hrs at room temp. afterwards, cells might start changing shape/ breaking down
ESR:
room temp: test within 4hrs
- test how fast rbc settle
- if refrigerated: up to 12 hrs
Reticulocyte count:
room temp: stable up to 6hrs
refrigerated: up to 72 hrs
what type of tubes does molecular test specimen use
Use plasma preparation tubes
- designed to keep RNA stable
*molecular test like Hepatitis C
why do we need to be careful when collecting for molecular test specimen
as the RNA materials are extremely unstable.
storage of molecular test specimens
short term:
4°C (refrigerated) - up to 48 hours
long term:
-80°C (freeze, ultra-cold freezer) - beyond 48 hrs
must move plasma to a different tube (aliquot tube)
types of culture specimens in microbiology specimens
Blood cultures
Urine cultures
Throat swabs
Wound swabs
- shld be transported to the lab immediately
why should we transport the microbiology specimens immediely
We’re trying to find what germs (bacteria) are making someone sick
Some germs die quickly if not handled properly
Other germs might grow too much
Either way, this can lead to wrong results
what are the source of error in urne test results
Cellular Elements decompose.
-cell in the urine start falling apart
Bilirubin breaks down to biliverdin.
Bacteria multiply.
- it multiply quickly inn warm urine
storage of urine specimen
room temp (short term) : 2hrs, keep away from bright light
refrigerated (long term): good for both regular urine tests
For longer storage, refrigerate the urine sample for urinalysis and culture and sensitivity testing.
- good for culture test
urine cytology
looking for cancer cells
hence, must be checked immediately
OR
add ethanol (special preservative)
Refers to a series of procedures that are performed on biological specimens (e.g blood, urine) after they have been collected and before they are analyzed in a laboratory.
specimen processing
- this is where the specimens are identified and logged/ accession
- time of processing that is required must be evaluated if it is suitable/ acceptable for testing.
this is where specimens are received and prepared for testing
Central/ Specimen Processing Area
(Aka lab control, triage )
A screening and prioritizing area
Prioritizing: it will screen the specimen to see whether it is a STAT
true or false:
STAT test are performed before any other
true
after processing STAT test is completed, where are they usually placed
in a special rack marked “STAT” in the testing area
- anyone delivering a STAT specimen to the testing area must notify the personnel that the STAT specimen is there and receive verbal acknowledgment from the person who will preform the testing that he or she is aware a STAT specimen has been delivered.
STAT
Short turn a round time/ immediately
*fee of a STAT test is much higher that a regular test
Involves evaluation of whether a given specimen type is appropriate for specific testing procedures
Specimen suitability
What happens if the specimen is unsuitable
Must be rejected for testing and new specimens must be obtained
*if inadequate of excess = rejected
Who should if not be inadequate of excess of specimen
As if should be in equal proportion b a of the blood to additive ratio
Reasons why specimens are rejected for
Chemistry specimen:
Hematology:
Chemistry specimen:
Hemolysis - may not be identified until specimen processing has already begun
QNS - quantity not sufficient
Hematology:
Hemolysis - may not be noticed until testing is complete
Clotting - edta is an anticoagulant to prevent blood from clotting
Overfilled/underfilled - affect the proportion/ ratio of the blood to additive
Example a of specimen rejection criteria
Transes
Are rejected specimens discarded?
No! Unless the ordering physician or nurse have been notified
Need to advice for recollection
What are some test that are seriously affected by
Hemolysis -
Test negatively affected by micro clots-
Hemolysis -
Potassium
Plasma-free hemoglobin
Troponin I and T
LDH
Test negatively affected by micro clots -
Hemoglobin
Hematocrtit
Platelet counts
Red and white blood cell counts
Examples of specimens that do not require further processing
Transes
What test which must be centrifuged
serum or plasma
What are the 3 phases involved in centrifugation
Pre centrifugation:
After specimen is collected and be fore centrifugation
Centrifugation:
When the specimen is centrifuge
Post centrifugation:
After centrifugation and before removal of serum or plasma
*test must continue to be kept in an upright position with stoppers in throughout the 3 centrifugation phases as is may cause
- loss of CO2
- increase of specimen pH
What are the tubes required for complete clotting in pre centrifugation
Non additive
Clotting activator
Gel containing tubes
- usually clot with in 30min, must be mixed adequately immediately after collection
Which tubes that clots within 5 minute a
Becton Dickinson (BD) Rapid Serum Tube (RST)
That contain thrombin
What is the usual time and temperature for a specimen to clot
30 to 60 in at 22 to 25 degree celcius
* tilt or invert to check for solid clot
Why is rimming the tube with an applicator stick not allowed
As is is used to release clots from the walls of the tube or the stopper before centrifugation and is is a potential source of hemolysis and contamination
What are some reasons of the delayed/ in complete clotting of blood
Anticoagulant medications (heparin, warfarin therapy)
High wbc count
Chilled specimen
Coagulopathies - bleeding disorder
The process of spinning specimen tubes in a centrifug
Centrifugation
a machine that spins blood and other types of specimens at a high number of revolutions per min (rpm)
Centrifuge
Expression of a speed of rotation
Revolutions per minute
What part of the centrifuge holds the tubes and spins
Rotor
Why do specimens not be centrifuge more that once
Hemolysis
An lyre deformation
After test results
What tube is collected for STAT chemistry
Green-top heparin tubes
To save time simply bcs plasma specimens can be centrifuged rightly t a way as opposed to serum specimens that must clot first
Rpm vs Rcf
Rpm, revolutions pre minute
- not fast the rot or is spinning
Rcf, relative centrifugation force
Has are the types of centrifuge
Small bench top centrifuge
Large bench top centrifuge
Large floor-standing centrifuge
Why does a centrifuge have enough space around it
To allow adequate ventilation
What happens if the centrifuge is balanced
May break test tube
Blood contents will must be a waste and may from aerosols which is harmful to the technologist
What happens if the centrifuge shakes, vibrates or is noisier than usual while it is turned on
Mean a that there is something unbalanced
- turn off immediately
Where should the specimens that require chilling should be processed
Temperature-controlled refrigerated centrifuge
As centrifuge generates heat during operation
What happens if the centrifuge time is to long or speed that is too high or too short/ speed that is too slow
Too long :
Hemolyze the specimens
Too short :
In complete separation of the specimen
Maintainance and calibrations of centrifuge must be done ?
Routinely
* clean the interior of the centrifuge with soap and water followed by bleach solutions
Regular maintainence of the ff :
Routine,y checked the ff :
Regular maintainence of the ff : (manufacturer/ supplier)
Balance
Brake mechanism
Speed and timer
Routine,y checked the ff : (medical technologist)
Gasket
Cover latch
Brushes
A strobe light instrument designed for measuring rpm
Tachometer
While the centrifuge is andar but no specimen shld be inside
After centrifugation has come to a complete stop, why should we be careful not to bump them
Can cause resispension of specimen s in tubes without separator gel
In post centrifugation, why do we have to visually inspect the gel tubes for barrier integrity
As the gel forms at a 45 degree angle in a fixed angle centrifugation
stopper must be removed to obtain the serum or plasma needed for testing using
Use of robotics
Commercially available stopper removal devices
Why do we have to wear a full-length face shield, holding the tube behind a bench-top splash shield, or working in a safety cabinet
To prevent exposure of aerosol, spills or splashes
- cover the stopper with gauze or tissue to catch blood drops or aerosol that may be released as it is removed
Pull it straight up and off: do not “pop” it off using a thumb roll technique
Where is the serum or plasma placed after removal from centrifuged specimen
Plastic sec tubes (aka transport tubes/ aliquot tube)
Portion of specimen taken for analysis
Aliquot
How do u transfer specimen into an aliquot tube
By using a pipette then cover or cap each aliquot tube as soon as it is filled
Do not pour as it increases the possibility of formation aerosol or splashing
What is the serum or plasma aliquots storage
Room tem -up to 8 hrs
2-8 degree celcius - more than 8 but not more than 48 hrs
Below -20 degree celcius - beyond 48hrs
- frozen samples should be thawed at room temp and inverted 10 to 20 times after thawing before testing
