Specimen Collection and Processing Flashcards
the most common procedure performed in the area of parasitology is the examination of a stool specimen for _
ova and parasites (abbreviated as O&P)
ova refers to the _ stage of parasite
egg
When present, the protozoan forms known as _ may be recovered from these samples.
trophozoites and cysts
_ stages, such as eggs, larvae, proglottids, and adult worms, may also be found.
Helminth
The typical stool collection protocol con- sists of three specimens, one specimen collected every other day or a total of _ collected in _.
3; 10 days
Stool samples from patients whose therapy includes _ oil should be col- lected prior to therapy or not until 5 to 7 days after the completion of therapy.
barium, bismuth, or mineral
Collection of speci- mens from patients who have taken antibiotics or antimalarial medications should be delayed for _ following therapy.
2 weeks
Amount of stool required for parasite study
2-5 g; “walnut size”
t/f. Urine should not be allowed to con- taminate the stool specimen because it has been known to destroy some parasites.
true
Stool should not be retrieved from toilet bowl water because _ may be con- fused with human parasites.
free-living protozoa and nematodes
To demonstrate the motil- ity of protozoan trophozoites, a _ specimen is required.
fresh
liquid stool must be examined within _
30 minutes
usually found in liquid stool
trophozoites
semiformed specimen should be evaluated within
1 hour
usually seen in semiformed specimen
protozoan cysts and trophozoites
formed specimens can be held for _
24 hours
substances that preserve the morphology of protozoa and prevent further development of certain helminth eggs and larvae
fixatives
recommended part of fixative and stool
3:1
The specimen must be fixed in the preservative for at least _ minutes before processing begins.
30
all-purpose fixative for the recovery of protozoa and helminths
formalin
5% formalin concentration ideally preserves
protozoan cysts
10% formalin concentration ideally preserves
helminth eggs and larvae
does not preserve parasite morphology adequately for permanent smears (-)
formalin
a plastic powder that acts as an adhesive for the stool specimen when preparing slides for staining
polyvinyl alcohol
PVA combined with Schaudinn solution has _ chloride base which can cause potential health problem.
mercuric
viable alternative to the use of PVA and Schaudinn fixative
SAF (sodium acetate formalin)
requires a single vial and it is mercury-free
SAF
SAF is easy to prepare, has a long shelf life, and can be used for preparing smears for staining with the modified acid-fast stain to detect _
coccidian oocysts
t/f
SAF-preserved specimens is not as clear in permanent stains as when mercury-containing preservatives are used.
true
SAF for permanent stains with _ provide better results
iron hematoxylin
Other alternatives to mercury-based PVA are the use of sub- stitute compounds containing copper sulfate or zinc sulfate
modified polyvinyl alcohol