Fecal Analysis Flashcards
is it okay find yeast in the stool
yes as long as it is not predominant
normal things to find in stool
cells, not WBC
electrolytes
undigested food and fat- amount can find certain disease states
normal color of stool
brown- due to sterco bilinogen
white or chalky stool meaning
blockage
if true blockage
-urobilinogen levels will be decreased
-increase in ALP
-conjugated bili= increased
other possible reasons for chalky stool
barium edema
laxatives
meaning of black stool
GI bled- upper
iron pills
red stool meaning
lower GI bled
after eating beats
increases in undigested blood can raise
BUN, but not creatinine
WBC found in stool mean
shigella- bacilli dysentery
could also be E.coli 0157 or C. diff
test for looking for undigested fat
fecal fat testing
fecal fat test
looks for steatorrhea-excess excretion of fat
> 7 indication
means malabsorption
macro observation of fecal fat
slimy, mucous= bad
micro tests done for fecal fat
neutral fat stain
split fat stain
neutral fat stain
-looks for triglycerides
-add 95% ethyl alcohol
-sudan 3 oil stain
> 60 large droplets =steatorrhea
split fat stain
looks for total fat content (fat acids and fatty acid salts)
add acetic acid and sudan 3
gently heat until bubbling
> 100 large droplets = steatorrhea
if you see a lot of fat order a
quantitative fecal fat to confirm
requires 3 day specimen of stool
restrictive to 100 grams of fat per day
gold standard for fecal fat
Van de Kamer
what happens in Van de Kamer
titration and extraction procedure
fat is extracted and lipids converted to fatty acids and titrated to a neutral end point with NaOH
fat measures- reported grams of fat for 24 hrs
normal <7 per day
occult blood testing
1 reason is for colon cancer: screen
occult- blood thats not visible
guaiac based testing
most common
main reagent: guaiac
-not most sensitive
-false negatives
blue=+
reaction for guaiac based on
pseudo peroaxidase activity of hgb
false reactions for guaiac
false + e.coli - contains some peroxidase
false - not enough blood and presence of ascorbic acid
IFOBT
immunochemical fecal occult blood test
principle= immunoassay that uses anti-human Hgb antibodies to globin portion of human Hgb in feces
precipitation
IFOBT detection
only detects blood in lower GI bled
less false + and -
not as much drug interaction
test for fetal Hgb in feces
Apt-Downey test
determine origin
Apt- downey based on
alkaline resistance of fetal Hgb
Apt- downey procedure
mix with emesis to release Hgb
centrifuge and divide into 2 tubes
-1control
-1 add NaOH
sit for 2 min
fetal= pink; resistant denaturation
adult= brown or yellow
