Stool examination is a part of routine and important laboratory examination of a patient

1. What is the stool or feces?
• Waste residue of indigestible material.
• Bile pigments and salts.
• Intestinal secretions, including mucus.
• Leukocytes that migrate from the bloodstream
• Epithelial cells that have been shredded from gut
lining.
• Bacteria and Inorganic material(10-20%) chiefly
calcium and phosphates. Undigested and
unabsorbed food.

2. Collection
 Collect stool in a dry and clean container
 uncontaminated with urine or other body
secretions, such as menstrual blood
 Collect the stool with a clean spatula or similar
object.
 Deliver immediately after collection
 Warm stools are best for detecting ova or
parasites.

3.  Do not refrigerate specimen for ova or
parasites.
A freshly passed stool is the specimen of
choice.
 If blood or mucous is present, it should be
included in the specimen.
 Because of the cyclic life cycle of parasites,
three separate random stool specimens are
recommended.

4. Stool Examination
 It is done for the identification of parasitic
infections which include.
 Protozoa and Helminths
 Protozoa exist in form of
 Trophozoites
 Cysts
 Helminths can be detected as
 Ova
 Larvae

5. Two methods of examination
 Macroscopic examination of stool
 Microscopic examination of stool

6. Macroscopic examination
Amount 100-200 g /day
Colour Yellow
Odour varies with PH of
stool and bacterial
fermentation
Consistency Solid to semisolid
Size and shape Formed
Gross blood, Mucous, Pus
Parasites and ova None

7. Microscopic examination
 Neutral fats 18%
 Undigested food None to small amounts
 Meat fibers, Starch None
 Eggs and segments None
of parasites
 Yeasts None
 Leukocytes None

8.  Microscopic examination is done by
examining smear.
 Two type of smears are used:
 Direct smear (unstained)
 Indirect smear (stained)
 Direct smear:
 Fresh stool + 0.1% NaCL sol = emulsion.
 Done for detection of Protozoa & their motility ;
 Entamoeba histolytica
 Giardia lamblia

9.  Indirect smear:
 Stool-saline emulsion + lugol’s iodine
 Background field - yellow
 Cysts are clearly visible
 Motile organisms - killed

10. Chemical examination
 PH 6.5-7.5
 Occult blood Negative
• Bile Negative in adults:
positive in children

11. Abnormalities in stool
 Stool odour:
 Normal odour is produced due to indole and
skatole.
 Varies with PH and bacterial fermentation and
decomposition
 Becomes foul smelling in amoebic dysentry
 Stool colour:
 Normal colour is due to stercobilinogen produced
by bacteria due to bile decomposition.
 In air turns brown due to formation of stercobilin

12.  Green: Becomes green in diarrohea.
 Black: resulting from bleeding into the upper
gastrointestinal tract ( malena).
 Red: In lower GIT bleeding.
 Clay coloured : Blockage of the common bile duct
 Blood in stool
 Presence of occult blood indicates
a. Carcinoma of colon b. Ulcerative colitis
 c. Adenoma d. Gastric carcinoma
 e. Diverticulitis f. Ulcers

13. Mucous in Stool
 Translucent gelatinous mucous clinging to the
surface of formed stool occurs in
a. Spastic constipation b. Mucous colitis
c. Emotionally disturbed patients
d. Excessive straining at stool
 Bloody mucous clinging to the surface suggests
a. Neoplasm b. Inflammation of the rectal
canal

14.  Mucous with pus and blood is associated with
 a. Ulcerative colitis b. Bacillary dysentery
 c. Ulcerating cancer of colon d.
 d. Intestinal tuberculosis
 Bile in Stool
1. Bile may be present in diarroheal stools.
2. Increased bile levels occur in Hemolytic
anaemia

15. Leukocytes in Stool
 Leukocytes found in different inflammatory and
infective conditions of the lower GI tract e.g.
Chronic ulcerative colitis, Chronic bacilliary
dysentery, Typhoid, shigellosis etc.
 Protozoa, Helminths and their Ova