ch 12: laboratory informatics and specimen handling and processing

13 examples of possible sources of preexamination error

• altitude

• dehydrated patient

• duplicate test orders

• exercise

• inadequate fast

• incomplete requisition

• medications

• patient stress

• pregnancy

• smoking

• strenuous exercise

• treatments (e.g., intravenous medications, radioisotopes)

• wrong test ordered

18 possible sources of examination/pre-analytical error

• misidentified patient

• antiseptic not dry

• expired tube

• failure to invert additive tubes properly

• faulty technique

• improper vein selection

• inadequate volume of blood

• inappropriate use of plasma separator tube (PST) or serum separator tube (SST)

• incorrect collection tube

• incorrect needle position

• incorrect needle size

• mislabeled tube

• mixing tubes too vigorously

• nonsterile site preparation

• patient position

• prolonged tourniquet application

• underfilled tube

• wrong collection time

5 possible sources of error during specimen transport

• agitation-induced hemolysis

• delay in transporting

• exposure to light

• failure to follow temperature requirements

• transport method (e.g., hand carried vs. pneumatic tube)

10 possible sources of error during specimen processing

• contamination (e.g., dust or glove powder)

• 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

• incomplete centrifugation

• mislabeled aliquot

• multiple centrifugations

• rimming of clots

2 possible sources of error during specimen storage

• exposure to light

• temperature change outside defined limits

measurand

quantity being measured

what kinds of tubes should be placed in an upright position IMMEDIATELY AFTER they have been mixed?

nonanticoagulant gel tubes, but remember that All tubes should be transported vertically w the stopper up

pneumatic tube system (PTS or P-tube)

a type of delivery system which consists of a network of long tubes that connect to sending and receiving stations in certain laboratory areas to stations located in various areas of the hospital, usually near a nurses’ station

13 tests unaffected by PTS transport

• albumin

• alkaline phosphatase

• AST

• chloride

• creatinine

• glucose

• sodium

• total bilirubin

• total protein

• BUN

• uric acid

• thrombin time

• WBC concentration

2 categories of infectious substances according to DOT and IATA + definitions

1. biological substance category A: an infectious substance capable of causing permanent disability or life-threatening or fatal disease in normally healthy humans or animals

2. biological substance category B: an infectious substance that does not meet the criteria for category A

what is the max time limit for separating all specimens as a general rule?

2 hours

how fast should specimens be transported to the laboratory?

asap

thermolabile

altered or destroyed by heat

3 specimens you need to keep at 37 deg C

• cold agglutinin

• cryofibrinogen

• cryoglobulin

10 specimens that need to be chilled in ice slurry or cooling rack

• adrenocorticotropic hormone (ACTH)

• ammonia

• catecholamines

• gastrin

• homocysteine (red top): ice slurry

• homocysteine (gel tube): cooler rack only

• lactic acid

• metanephrines, plasma

• parathyroid hormone (PTH)

• pyruvate

9 substances that need to be protected from light

• beta-carotene

• bilirubin

• folate

• vitamin A

• vitamin B₂

• vitamin B₆

• vitamin C

• urine porphobilinogen

• urine porphyrins

photosensitive

sensitive to light

QNS

quantity not sufficient

has plasma/serum been removed during postcentrifugation?

no. postcentrifugation means after centrifugation and before removal of serum or plasma

when should nonadditive, clot activator, and gel-containing tubes used for serum tests (e.g., SSTs) be centrifuged?

after clotting is complete, which is usually btwn 30-60 min

tubes that contain thrombin normally clot in

5 minutes

can plasma tests collected in anticoagulant tubes be centrifuged right away?

yes

aliquot

a portion of a specimen used for testing

biobank

a repository or storage facility where human biological samples such as blood, saliva, plasma, skin cells, and organ tissues can be stored, preserved, and cataloged for use in research for personalized medicine, for example

panic (critical) value

lab results considered life-threatening and thus require immediate intervention by a healthcare provider

read-back

a strategy where you get someone to read back the results you told them to write down over the phone to confirm the accuracy of what was written