frozen section and decalcification Flashcards
what is the CAP accreditation standard time for frozen section
20 mins
4 application for frozen section
Intra-operative consultations
Enzyme histochemistry
Immunofluorescent techniques
Lipid stains
benefits for enzymes in frozen sections
Enzymes are labile and rapidly degrade when removed from blood and fixed
Freezing tissue = best to preserve enzymes (especially in muscles)
benefits from immunofluorescnt techniques in frozen sections
Fixation will degrade Ab
Aldehyde fixatives create autofluorescence
benefits from lipid stains in frozen sections
Fixations will dissolve lipids
Neutral lipids (fat) can be visualized
what is freezing artifact
ice crystals in muscle that leaves holes in tissue
how to minimize freezing artifact
freeze rapidly using heat extractors, dry ice, or liquid nitrogen
what temp for sectioning at -7C to -13C
brain
liver
thyroid
what temp for sectioning at -13 to -16C
skin
liver
muscle
what temp for sectioning at -20 to -30C
breast
fatty tissue
what is used to freeze tissue in place
FSC
T/F frozen sections form ribbons
F
when tissue is on slide, what is used to fix
formalin or alcohol before staining with H&E
how is quality assurance demonstrated in frozen sectioning
comparison of frozen slide and paraffin slide to confirm
cause and resolution of chatter
Block being too cold or loose component
All levers tight and increase temperature of cryostat / warm block
cause and resolution of shattering
Cryostat is too cold (seen most in lymph nodes)
Increase temperature or heat from gloves
cause and resolution to compression
Block is too warm or Blade is too dull
Cool the block or new blade
cause and resolution to lines/scores
Defect in blade or Calcification (notify path)
New blade
cause and resolution to debris in cryostat
Static electricity
Humidify room or wipe down cryotome with alcohol
what disinfectant used at end of day
70% ethanol
how should Oxivir/Cavicide be used
when cryostat is defrosted and decontaminated
what method of disinfectant is dangerous for cryostat
heating chambers to vaporize formalin or gluteraldehyde
cons of UV light disinfectant
cannot pentrate dirt so it has to be clear before use
what causes the cryostat to overheat
dusty coils
what pH is calcium soluble at
4.5 or less
what solutions are used to routinly used to decal
formic acid with formalin (3-10 days)
HCL or nitric acid when more rapid is needed (<2 days)
T/F tissues can be decalcified whenever
F - tissues must be fixed before decal
what hazard can occur when decal with HCl
must be washed after HCl as mixing with formalin = bis-chloromethyl ether (carcinogen)
what 3 methods are used in decal
simple acid
ion exchange resins
EDTA
how does simple acid decal work
submerge in solution with agitation to prevent calcium ion surrounding the tissue, then replace solution
how does ion exchange resins decal work
resins exchange ammonium for calcium ions to prevent saturating solution = quicker decal and less replacement
how does EDTA decal work
binding metal ions without affecting other tissue components = good to use where acids may destroy labile tissue.
BUT takes weeks to complete
what 3 methods are used to detect endpoint
chemical
radiography
physical
how does chemical endpoint detection work
decal solution is neutralized with ammonium hydroxide then ammonium oxalate to form calcium oxalate (white precipitate)
white precipitate = calcium present and more decal needed
how does radiography endpoint detection work
Ca2+ is solid white on X rays
how does physical endpoint detection work
bending the tissue to determine if fully decal (unreliable and not recommended as bending creates artifacts)
after decal, what is used to neutralize the residual acid
lithium carbonate
how is overdecal recognized
poor nuclear staining
pale red nuclei = loss of basephilia
how to correct for over decal
sodium bicarbonate overnight and restain
