AUBF Fecalysis

normal stool output

100-200g per day

composition of feces

¾ water ¼ solid

30% nonpathogenic bacteria

Escherichia coli  (anaerobic)

Bacteroides fragilis (aerobic - produce gas)

trypsin

protein metabolism

chymotrypsin

protein metabolism

amino peptidase

lipids metabolism

lipase

lipids metabolism

bile salts

lipids metabolism

cholesterol breakdown

acts surfactant/detergent to degrade chole

production of enzymes

most are from pancreas

bile salts from gall bladder in liver

Causes of stool odor

skatole

indole

butyric acid

product of bacterial fermentation

stool pH

near neutral/ slightly alkaline/slightly acidic/ neutral

6.0-6.5

Acidic feces

carbohydrate fermentation

= organic acids: lactic acid, pyruvic acid, formic acid

Alkaline feces

protein fermentation

= ammonia, sulfides, amines

consistency of stool

normal: not too soft, not too hard, not too watery

trace amount presence of mucus

large intestine

abundant mucus

small intestine

presence of mucus in stool

shigellosis and salmonellosis

reason for fecalysis: early detection of GI bleeding

associated with colorectal cancer

reason for fecalysis: steatorrhea

lipids in stool

reason for fecalysis: detect pathogenic bacteria & parasites

hard to culture, presence of normal microbiota

gold standard for fecal fat analysis

2-3 day fecal collection (72 hrs) for quantitative tests

stool preservation

refrigerate (never in freezer)

dry ice

formalin

alcohol

methiolate (iodine formaldehyde - iodine toxic for tropohozoites)

polyvinyl alcohol fixative

Light to dark brown

normal (stercobilin)

black

upper GIT bleeding (oxidized blood) - melena

iron therapy

charcoal 

bismuth (antacids)

melena

black tarry stool

red

lower GIT bleeding (hematochezia)

beets and food color

rifampin

pale0yellow, white, gray

bile obstruction - no urobilin

barium sulfate

green

biliverdin

oral antibiotics

green veggies

green food coloring

butter-like (shiny and very soft)

cystic fibrosis (no enzymes, no breaking down of lipids = lipid increase in stool)

bulky or frothy

proteins/lipids present

bile duct obstruction

pancreatic disorders

steatorrhea

mucus, blood-streaked mucus

inflammation and infection

colitis

dysentery

malignancy

constipation (severe dehydration)

GIT lining damage

ribbon-like /flattened/ pencil-like

narrow intestinal lumen

spastic colitis

lower colon obstruction

syphilis

rice watery

cholera

pea soup

typhoid

scybalous (goat droppings)

constipation

spastic colitis

decrease fluid intake

small caliber

cancer

tumor

ulcer

large caliber

hirschsprung’s disease - enlargement of colon, no ganglion cells, shrunken rectum

Bristol stool chart: type 1

separate hard lumps, hard to pass

Bristol stool chart: type 2

sausage-shaped but lumpy

Bristol stool chart: type 3

sausage-like, with cracks on surface (normal)

Bristol stool chart: type 4

sausage/snake-like, smooth and soft

Bristol stool chart: type 5

soft blobs with clear cut edges

Bristol stool chart: type 6

fluffy pieces with ragged edges, mushy stool

Bristol stool chart: type 7

watery, no solid

normal fats per day

5g/day fatty diet

1-4g/day free fat diet

steatorrhea deficiency

lipase = fibrocystic disease of pancreas'

lymphatic obstruction in TB

screening and definitive test for steatorrhea

screening: microscopic exam of free fat globules

definitive: fecal fat determination

qualitative test

maldigestion and malabsorption

maldigestion - undigested triglyceride present

malabsorption - fatty acid in stool present

neutral fat stain

detect triglyceride

suspension + 95% ETOH + Sudan III

orange droplets > 60/hpf = steatorrhea

split fat stain

detect fatty acid

emulsified stool + 36% acetic acid + Sudan III

100 orange droplets (6-75 um) = increased fatty acid = malabsorption = steatorrhea

Van De Kamer Titration

quantitative test confirmatory for steatorrhea

gold standard for fecal fats

titration with NaOH

sample: 3 day stool

normal = 1-6g fats/day

steatorrhea = >6g fats/day

Acid steatocrit

for pediatric population

not exact quantification of amount of fats

HCl

creatorrhea

abnormal excretion of muscle fibers in feces

malabsorption of fibers

emulsified stool +10% eosin (stand for 3 minutes)

abnormal = >10 undigested muscle fibers

digestion of muscle fibers striations

no striations - completely digested

unidirectional striations - partially digested

two directional striations - undigested

undigested striated muscle fiber indicate:

biliary obstruction, gastrocolic fistulas, pancreatic insufficiency (cystic fibrosis)

diarrhea with WBC

salmonella

shigella

yersinia

EIEC (e. coli)

campylobacter

• watery  diarrhea

diarrhea without WBC

enterotoxin producing bacteria: s. aureus and vibrio cholerae

virus

parasites

fecal leukocyte determination

wet preparation: loeffler’s methylene blue (better visibility of WBC)

dry preparation: Wright’s/Giemsa stain

Lactoferrin Latex agglutination test

from neutrophil secondary granules (WBC not normal in stool)

(+) agglutination = invasive bacterial pathogen

three mechanisms of diarrhea

osmotic - low fecal electrolytes, high fecal osmolality, acidic pH

secretory - high fecal electrolytes, low fecal osmolality, neutral pH

Altered motility - 

osmotic diarrhea conditions associated

maldigestion/malabsorption

disaccharide deficiency (lactose intolerance)

celiac sprue

poorly absorbed sugars

laxatives

magnesium-containing antacids

amoebiasis

antibiotic administration

secretory diarrhea conditions associated

crohn’s disease

stimulant laxatives

hormones

inflammatory bowell disease

endocrine disorders

• cohn’s disease

• ulcerative colitis

• lymphocytic colitis

• dicerticulitits

neoplasm

altered motility

peristalsis wave

irritable bowel syndrome

cramping

bloating

flatus

diarrhea

constipation

early dumping syndrome (10-30 mins after meal)

• normal = 35-100 minutes

late dumping syndrome (2-3hrs after meal)

fecal occult blood test FOBT positive result

blue

FOBT principle and substrate

pseudoperoxidase activity of hemoglobin

sodium hydroxide

FOBT chromogens

benzidine (most sensitive, toxic and carcinogenic)

guaiac (preferred)

O-toluidine

false positive FOBT

dietary pseudoperoxidase

red meat (3days)

melon, broccoli, cauliflower, horseradish (3 days)

aspirin and antiinflammatory drugs (7 days)

false negative FOBT

reducing agents

ascorbic acid and iron therapy

APT Test or Downy test

for fetal hemoglobin differentiation using NaOH

apt test positive result

pink solution = fetal blood

yellow brown = maternal blood

false positive apt result

thalassemia major patients 

fecal carbohydrates (lactose intolerance)

clinitest - for reducing sugar (lactose)

pH - <5.5 because of bacterial