FECALYSIS Flashcards
Normal amount of excreted stool
100-200g
Normal stool color is caused by
Urobilin/Stercobilin
Upper GI bleeding, iron, charcoal bismuth stool color
Black
Lower GI bleeding, beets, food coloring, rifampin stool color
Red
Bile duct obstruction, barium sulfates stool color
Pale yellow, white, gray (acholic)
Biliverdin, oral antibiotics, green vegetable stool color
Green
Prussian blue, grape, soda stool color
Blue
Porphyria stool color
Violet/Purple
Bile duct obstruction, pancreatic disorders, steatorrhea stool appearance
Bulky/Frothy
Cystic fibrosis stool appearance
Butter-like
Colitis, dysentery, malignancy, constipation stool appearance
Mucus-streaked, blood-streaked
Slender, ribbon/noodle-like stool is seen in
Intestinal obstruction or constriction
Rice watery stool is seen in
Cholera
Typhoid stool color
Pea soup
Constipation stool appearance
Hard/Scybalous (goat droppings)
Bristol stool chart: watery, no solid pieces
Type 7
Bristol stool chart: fluffy pieces with ragged edges, mushy stool
Type 6
Bristol stool chart: soft blobs with clear-cut edges
Type 5
Bristol stool chart: most common stool type
Type 4
Neutral fat stain value for steatorrhea
≥60 droplets/HPF
Reagents for neutral fat stain
95% ethanol + Sudan III
Reagents for split fat stain
36% acetic acid + Sudan III
Gold standard for steatorrhea
Van de Kamer titration
Van de Kamer sample collection duration
3 days (72 hours)
Normal value for fat excretion in stool
1-6 g fats/day
Abnormal fat excretion in stool (Van de Kamer test)
> 6 g fats/day
Rapid test for fat excretion similar to microhematocrit
Acid steatocrit (quantitative fecal fats)
Test using microwaved stool for analysis
Hydrogen nuclear magnetic resonance spectroscopy
Abnormal muscle fiber secretion in stool is called
Creatorrhea
Reagent for muscle fiber detection in stool
10% Eosin
Appearance of undigested muscle fibers
Striations in both directions
Undigested muscle fibers are seen in
Biliary obstruction, cystic fibrosis
Abnormal value for undigested muscle fibers
> 10
Neutrophils in feces indicating invasive condition
≥3/HPF
Diarrhea with WBCs in stool indicates
Salmonella, Shigella, Yersinia, enteroinvasive E. coli, Campylobacter
Diarrhea without WBCs in stool indicates
Toxin-producing organisms, parasites, viruses
Screening test for colorectal cancer
Guaiac Fecal Occult Blood Test (gFOBT)
Principle of gFOBT
Pseudoperoxidase activity of hemoglobin
Chromogen used in gFOBT
Guaiac
False positive gFOBT interference
3 days (food-related), 7 days (aspirin, NSAIDs)
False negative gFOBT interference
3 days (Vitamin C, iron with Vitamin C)
Immunochemical FOBT detects
Globin using anti-HGB antibodies
Porphyrin-based FOBT detects
Fluorescent porphyrins from heme
APT Downey test pink solution indicates
Fetal blood (alkaline-resistant)
APT Downey test yellow-brown solution indicates
Maternal blood (denatured by alkali)
X-ray film test detects pancreatic enzyme
Trypsin
Absence of trypsin is seen in
Cystic fibrosis
Fecal carbohydrate test assesses
Lactose intolerance
Clinitest result >0.5 g/dL indicates
Carbohydrate intolerance
Sensitive indicator of pancreatic insufficiency
Elastase-1
Test to differentiate malabsorption and maldigestion
D-xylose test
Low urine D-xylose indicates
Malabsorption
Normal urine D-xylose indicates
Maldigestion
Acute diarrhea duration
<4 weeks
Major mechanisms of diarrhea
Secretory, osmotic, altered motility
Normal fecal osmolarity
290 mOsm/kg
Normal fecal Na level
30 mmol/L
Normal fecal K level
75 mmol/L
Secretory diarrhea fecal osmotic gap
<50 mOsm/kg
Osmotic diarrhea mechanism
Retention of water and electrolytes in large intestine
Causes of osmotic diarrhea
Maldigestion, malabsorption, lactose intolerance, laxatives, antacids
Diarrhea caused by altered motility
IBS, rapid gastric emptying, dumping syndrome