DIAGNOSTIC PROCEDURES (STOOL AND BLOOD) Flashcards
clearance period of antacids, antidiarrheals, barium, bismuth, laxatives (leaves crystalline residues)
7-10 days
clearance period of antimicrobial agents (decrease the number of protozoans)
2-3 weeks
clearance period of gallbladder dyes
3 weeks
sufficient quantity of stool for routine O & P (Oval and Parasite)
2-5 um (thumbsize/3-5 tablespoon)
possible contaminants of stool
soil, water, urine
true or false:
place the specimen in a dry, clean, leak proof, tupperware
dry, clean, leak proof, waxed container with a screw cap (1/2 pint)
what should the label of the container include?
patient’s name, age, sex, date, and time of collection
number of specimens examined
3 specimens collected in different days within 10 days
purpose of 3 specimens collected in different days within 10 days
to recover parasites that shed diagnostic form intermittently
maximum time between collection and examination of liquid specimens
30 mins after collection
maximum time between collection and examination of soft/semi-formed specimens
1 hour
maximum time between collection and examination of formed specimens
up to 24 hours
what should not be done with the stool specimen
- leave at room temp
- incubate
- freeze
beyond one hour, stool must be ______ for up to 24 hrs
refrigerated
what should be done for longer periods of preservation
2 vial system (10% formalin and PVA/Polyvinyl Alcohoi)
ratio of stool to preservative
1:3
all purpose fixative
10% formalin
used to fix and stain
merthiolate-iodine formalin
can be used for permanent stains
sodium acetate acetic acid formalin
contain mercuric chloride
Schaudinn’s fluid & Polyvinyl alcohol
toxic to man
mercuric chloride
Schaudinn’s fluid with PVA
Polyvinyl Alchohol
contain zinc sulfate/copper sulfate
modified PVA
can be used for molecular testing
Modified PVA
formalin based preservative
- 10% formalin
- Merthiolate-iodine-formalin (MIF)
- Sodium acetate-acetic acid formalin (SAF)
PVA preservative
- Schaudinn’s fluid
- Polyvinyl alcohol
- Modified alcohol
purpose of 2 vials of stool spx is needed
for formalin based and PVA preservative
tests that use 10% formalin
- Wet mount
- Concentration Technique
- Immunoassay
tests that use Merthiolate iodine formalin
- Wet Mount
- Concentration technique
tests that use sodium acetate acetic acid
- Wet Mount
- Concentration technique
- Permanent stain
- Immunoassay
tests that use Schaudinn’s fluid
permanent stain
tests that use Polyvinyl Alcohol (PVA)
permanent stain
tests that use modified PVA
permanent stain
true or false
Permanent stain usually uses PVA
TRUE
lateral flow assay/immunochromatographic assay is used for coproantigens of:
- G. lamblia
- E. histolytica
- C. parvum
cysts are present the highest in ____
formed stool
trophozoites are present the highest in ________
watery stools
mixture of cyst and trophozoites are present in _____
soft and loose stool
true or false
the drier the stool, the higher the amount of trophozoite
false; the drier the stool, the higher the amount of cysts
normal color of stool
brown
brown color of stool is due to
urobilin/stercobilin
black/tarry discoloration of stool is due to
upper GI tract bleeding
mucoid and bloody stool is due to
dysentery
normal consistency of the stool
soft to well-formed
consistency gives clues on _______ present in abundance
parasite (protozoans) stage
consistency determines sensitivity of ________
egg counting techniques
macroscopic structures
adult worms, scolices, proglottids
necessary for identification of solium and saginata
gravid proglottids
microscopic examination for O&P examination
- Wet Mount
- Concentration technique
- Permanent stain
has poor sensitivity and prone to false negative
wet mount
wet mount aka
direct fecal smear
wet mount preparation
~ 2 mg of stool an a drop of 0.85% saline (NSS)
useful in detection of motile protozoans trophozoites, helminth eggs, and larvae
wet mount/direct fecal smear
wet mount may be stained by ________ to enhance the visibility of nuclear structures in protozoal cysts and aid in detecting glycogen inclusions
iodine (lugol’s & D’ Antoni’s)
use _____________ for trophozoites
Mair’s Buffered Methylene Blue
sedimentation procedures
- formalin ether (or ethyl acetate) concentration technique
- acid-ether concentration technique (AECT)
fixative for formalin ether concentration technique
formaline
used to remove fats in formalin ether concentration technique
ether/ethyl acetate
can be used for specimens preserved in formalin, MIF, SAF
formalin ether (ethyl acetate) concentration technique
formalin ether (ethyl acetate) concentration technique is efficient in recovering most ________ and __________ including ______
protozoan cysts; helminths eggs and larvae; operculated eggs
formalin ether (ethyl acetate) concentration technique is moderately effective to
schistosome eggs
true or false
formalin ether (ethyl acetate) concentration technique has more distortion of protozoal cysts compared to zinc sulfate floatation
false
- it has less distortion
this removes/precipitates albuminous/mucoidal substances in AECT
40% HCl
example of albuminous/mucoidal substance that is removed or precipitated by 40% HCl
proteins
AECT is recommended for
- animal parasites
- Trichuris
- Capillaria
- Schistosoma eggs
loss of parasite to the plug of debris and possible destruction of protozoan cysts is due to ________
acidity of medium
top to bottom of the tube in sedimentation techniques
- Ether/Ethyl Acetate (TOP)
- plug of debris
- sedimentation medium (formalin/hydrochloric acid)
- sediment (parasites) (BOTTOM)
where is the parasite located in sedimentation technique?
sediments
sedimentation medium
formalin/hydrochloric acid
which is decanted in sedimentation technique
ether/ethyl acetate, plug of debris, sedimentation medium
what should be done to loosen the plug of debris
wring the stick
Flotation procedures
- zinc sulfate flotation
- brine’s flotation
- sheather’s flotation
Zinc Sulfate Flotation is not used in ff
- operculated eggs
- heavy eggs/larvae
- thin shelled eggs (hookworm eggs)
SG for 33% ZnSO4 for processing fresh feces in Zinc Sulfate flotation
1.18
SG is adjusted to ___ if specimen is formalinized
1.2
Zinc Sulfate flotation is unreliable for the recovery of the ff:
- nematode larvae
- infertile eggs of Ascaris
- eggs of Taenia
- eggs of Schistosomes
- Cestode and Trematode eggs
if thin shelled eggs are put into hypertonic solution it will _____, causing ____ SG
shrink; increased
Brine’s flotation uses __________ with a SG of 1.2
saturated salt solution
is centrifugation required for Brine’s flotation
no
brine’s flotation is not applicable for the following
operculated and thin shelled eggs
Sheather’s flotaion uses ___________
boiled sugar solution preserved with phenol
Sheather’s flotation is preferred to use for concentrating _____
coccidian oocysts
SG for Sheather’s flotation
1.25 - 1.27
SG of medium (<,>,=) SG of parasite
> (parasite will float)
stains used in permanent staining
- iron hematoxylin
- wheatley’s trichrome
- modified trichrome
- modified acid-fast stain
more commonly used in permanent staining
iron hematoxylin and Wheatley’s trichrome
shades of gray-blue to black w/ pertinent nuclear structures in darker shades
iron hematoxylin
cytoplasm color in Wheatley’s trichrome
blue green
color of nucleus, cytoplasmic inclusions, Charcot Leyden crystals in Wheatley’s trichrome
red/red purple
10x the Wheatley’s Trichrome dye content
modified trichrome
color of microsporidians in Modified Trichrome
pink to red
weaker acid decolorizer
modified acid-fast stain
used in modifies acid fast stain
1-3% HsSO4 (Sulfuric Acid)
is used to demonstrate Cryptosporidium, Cytoisospora, Cyclospora oocysts
modified acid-fast stain
acid fast variables
Cytoisospora and Cyclospora
artifact that resembles mature Entamoeba histolytica cysts
Neutrophil
macrophage, squamous, and columnar epithelial cells resembles:
amebic trophozoites
yeast, fungal conidia, mushroom spores, diatoms
Protozoan cysts or helminth eggs
mite eggs resemble
hookworm
what differentiate mite eggs from hookworms eggs
4-8 packets
pollen grains
Taenia and Ascaris eggs
what differentiates pollen grains from Taenia eggs
Taenia eggs have 6 hooklets inside
amount of stool used in Kato thick smear
~50-60 mg
contents of the mixture where cellophane is soaked
glycerin and malachite green
clearing agent used in kato thick smear
glycerin
provides green background
malachite green
process of kato thick smearn
~50-60 mg of stool is placed over a glass slide and covered with cellophane that has been soaked in a mixture of glycerin and malachite green
useful in mass stool examination and surveilance studies
kato thick smear
useful for assessing worm burden and monitoring the efficacy of antihelminthics especially in cases of soil transmitted helminths and schistosomiasis
egg counting techniques
STH
Soil Transmitted Helminths
technique that does not dry out easily
kato thick smear
modification of the kato thick smear which uses a measured amount of stool which has been sieved through a wire mesh
kato katz
formula for kato katz
eggs per gram feces (epg) = number of eggs counted x factor (depends on template used)
standard template from CDC
1.5 mm thick with a 6 mm hole
amount of feces delivered and factor in 1.5 mm thick with a 6 mm hole template
41.7 mg; factor 24
amount of feces delivered and factor in 1mm thick with a 9mm hole
50 mg; 20
amount of feces delivered and factor in 0.5 mm thick with a 6.5 mm hole
20 mg; 20
makes use of calibrated flask and stoll pipettes
stoll dilution
diluent used in stoll dilution
0.1 normal sodium hydroxide
saponifying agent
0.1 normal sodium hydroxide
used to determine severity of Schistosoma infection
Faust Maloney egg hatching technique
Faust Maloney egg hatching technique involves counting of _______
Schistosoma miracidia
uses moistened soil or granulated charcoal
copro culture
larvae is harvested using _____ in copro culture
Baerman technique
involves applying positive stool to a filter paper strip and placing it into a test tube with distilled water
harada-mori or test tube culture method
days and temp harada mori is done (ewan HAHA)
10 days at 25-30 degree Celsius
used to detect eggs of E. vermicularis
perianal swab
best time to collect specimen for E. vermicularis
Early morning before bath
what is added to improve visualization of eggs
xylene/toluene
for the diagnosis of amoebiasis (E. histolytica infection)
Sigmoidoscopy
also known as scotch tape/cellulose tape method
perianal swab
entero test is useful for the recovery of the ff
- G. lamblia
- C. parvum
- S. stercoralis
- rhabditiform larva in stool
true or false
eggs of S. stercoralis is seen in feces
false; it is never seen in feces
other terms for entero test
duodenal capsule test , string test
contact time of entero test
4 hrs
collected material must be analyzed within
1 hr
preferred specimen especially for malaria to avoid distortion of parasite morphology
fresh, non anticoagulated
non anticoagulated blood
directly from skin/capillary puncture
anticoagulated blood must be delivered to the laboratory within ___ and must be processed within ____
30 mins; 1hr
preferred time of collection for patient with malaria
before the next anticipated fever spike (theoretically; in reality, at the height of fever)
preferred time of collection for filariasis
depends on the periodicity
preferred time of collection for elephantiasis (W. bancrofti)
nocurnal periodicity (10pm to 2am)
gold standard for malaria
examination of stained smears
uses 2-3 drops of blood which are mixed to form a circular smear
thick blood smear
used to dehemoglobinize the blood before making thick blood smear
distilled water
used for rapid diagnosis or screening of malaria and for demonstrating trypomastigote and microfilariae
thick blood smear
prepared in a way that the smear is thick at one end, thin and feathery at the other end
thin blood smear
used for species identification
thin blood smear
thick smear
2-3 drops (6uL); 1.5 cm diameter
thin smear
1 drop (2-3 uL)
stain recommended for detection and identification of blood parasites; buffer pH: 7-7.2
giemsa stain
best stain to use for blood parasites
giemsa stain
allows visualization of stipplings
giemsa stain
not optimal for blood parasites; buffer pH: <6.8
wright’s stain
used to demonstrate the detailed structures of microfilariae
delafield hematoxylin
delafield hematoxylin requires dehemoglobinization of thick films with ________
2% formalin in 1% acetic acid
romanowsky stains
giemsa stain and wright’s stain
blood smears are stained with acridine orange
kawamoto technique
color of nuclear DNA and cytoplasmic RNA in kawamoto technique
nuclear DNA: green
cytoplasmic RNA: red
STAT specimen for Parasitology
CSF and blood specimen for Malaria