2. Stool Analysis
What is the stool or
feces?
1. Waste residue of indigestible material
(cellulose during the previous 4 days)
2. Bile pigments and salts
3. Intestinal secretions, including mucus
4. Leukocytes that migrate from the
bloodstream
5. Epithelial cells that have been shade
6. Bacteria and Inorganic material(10-20%)
chiefly calcium and phosphates. Undigested
and unabsorbed food.
3. Random Collection
1. Universal precaution
2. Collect stool in a dry,clean container
3. uncontaminated with urine or other body
secretions, such as menstrual blood
4. Collect the stool with a clean tongue
blade or similar object.
5. Deliver immediately after collection
4. Ova and parasites
collection
1. Warm stools are best for detecting ova or parasites.
Do not refrigerate specimen for ova or parasites.
2. If the stool should be collect in 10 % formalin or PVA
fixative, storage temperature is not critical.
3. Because of the cyclic life cycle of parasites, three
separate random stool specimens are
recommended.
5. Enteric pathogen collection
1. Some coliform bacilli produce antibiotic substances that
destroy enteric pathogen.Refrigerate specimen
immediately.
2. A diarrheal stool will usually give accurate results.
3. A freshly passed stool is the specimen of choice.
4. Stool specimen should be collected before antibiotic
therapy, or
as early in the course of the disease.
5. If blood or mucous is present, it should be included in the
specimen
6. Interfering factors
1. Patients receiving tetracyclines, anti-diarrheal drugs,
barium, bismuth, oil, iron , or magnesium may not yield
accurate results.
2. Bismuth found in toilet tissue interferes with the results.
3. Do not collect stool from the toilet bowl.A clean, dry
bedpan is the best.
4. Lifestyle, personal habbits, environments may interfere
with proper sample procurement.
7. Normal values in stool Analysis
Macroscopic examination Normal
value
Amount 100-200 g / day
Colour Brown
Odour Varies with pH of stool
and depend on bact-
erial fermentation
Consistency Plastic, not unusual to
see fiber, vegetable skins.
Size and shape Formed
Gross blood,Mucous,Pus, Parasites None
8. Normal values in stool
analysis
Microscopic examination Normal values
Fat (Colorless,
neutral fat (18%)and fatty acid
crystals and soaps)
Undigested food None to small amount
Meat fibers, Starch, Trypsin None
Eggs and segments of parasites None
Yeasts None
Leukocytes None
9. Normal values in stool analysis
Chemical examination Normal values
Water Up to 75 %
pH 6.5-7.5
Occult blood Negative
Urobilinogen 50-300 µg/24hr
Porphyrins Coporphyrins:400-1200µg/24hr
Uroporphyrins:10-40 mg/24hr
Nitrogen <2.5 g/24hr
10. Normal values in stool analysis
Chemical examination Normal values
Bile Negative in adults:positive in
children
Trypsin 20-950 units/g( positive in
small amounts in adults; present in
greater amounts in normal children.
Osmolarity used 200-250 mOsm with
serum osmol- arity to calculate
osmotic gap
Sodium 5.8-9.8 mEq / 24hr
11. Normal values in stool analysis
Chemical examination Normal values
Chloride 2.5-3.9 mEq / 24 hr
Potassium 15.7-20.7 mEq /24 hr
Lipids ( fatty acid) 0-6 g / 24 hr
12. Clinical Implications
1. Fecal consistency may be altered in various
disease states
a. Diarrhea mixed with mucous and red blood cells is
associated with
1. Typhus 2. Typhoid 3.Cholera
4. Amebiasis 5. Large bowel cancer
13. Clinical Implications
b. Diarrhea mixed with mucus and white blood
cells is associated with
1. Ulcerative colitis 2. Regional enteritis
3. Shigellosis 4. Salmonellosis
5. Intestinal tuberculosis
14. Clinical Implications
C. ”Pasty” stool is associated with a high fat content
in the stool:
1. A significant increase of fat is usually detected on gross
examination
2. With common bile duct obstruction, the fat gives the
stool a putty- like appearance.
3. In cystic fibrosis, the increase of neutral fat gives a
greasy, “butter stool” appearance.
15. Stool Odor
Normal value Varies with pH of stool and diet.
Indole and sketole are the substances that
produce normal odor formed by intestinal bacteria
putrefaction and fermentation.
Clinical implication.
1. A foul odor is caused by degradation of
undigested protein.
2. A foul odor is produced by excessive carbohydrate
ingestion.
3. A sickly sweet odor is produced by volatile fatty
acids and undigested lactose
