EXAMINATION OF STOOL

STOOL ANALYSIS
A stool analysis is a series of tests done on a stool (feces) sample to help diagnose certain
conditions affecting the digestive tract

• These conditions can include infection (such as from parasites, viruses, or bacteria),
poor nutrient absorption, or cancer. Laboratory analysis includes macroscopic,
microscopic examination, chemical tests, and microbiologic tests.

• The stool will be checked for color, consistency, weight (volume), shape, oduor, and
the presence of mucus and parasites stages.

• The stool may be examined for hidden (occult) blood, fat, meat fibers, bile, white
blood cells, and sugars called reducing substances.

• The pH of the stool also may be measured.

• A stool culture is done to find out if bacteria may be causing an infection.

Macroscopic Examination

• abnormal features

• adult or segment

• Color

• Consistency

Microscopic Examination

• WCB, RBC, Mucus, Yeast, Trophozoite, Cyst, Egg, Larvae, Adult worm

Chemical Examination

• Fecal PH test

• Fecal fatty acid testing

• Testing feces for Occult Blood

MACROSCOPIC EXAMINATION

1. Color:
 Brown is normal color, results from the intestinal oxidation of stercobilinogen to
urobilin.
 Bright red to dark red to black stools occur when iron or bismuth is taken or when
there is intestinal hemorrhage.
 Pale yellow stools indicate the biliary obstruction, steatorrea, and also associated with
diagnostic procedures that use barium sulfate
 White stools occur when there is obstructive jaundice.
 Green stool may be observed in patient taking oral antibiotic, because of oxidation of
bilirubin to biliverdin
2. Consistency:
 Degree of moisture, will be a guide as to whether the trophozoite stage or the cyst
stage of protozoa is likely to present.
• Formed, write “F”

• Soft , write “S”

• Loose , write “L”

• Watery , write “W”

3. Abnormal features:
• If mucus is present write “M”, and “B” if blood is present.
 • The presence of mucus coated stool is indicative for intestinal inflammation or
irritation.

4. Adult worm or segments

• The feces may have adult helminthes or segments present such as Ascaris
lumbricoides, Entrobius vermicularis, or Taenia spp. Gravid segment, these
can be seen by naked eye.

• And frequently motile for several days and may migrate to the top of the
container If several specimens are received at the same time; those containing
blood and mucus should be examined first, followed by liquid specimens.
These specimens are the most likely to contain amoebic trophozoites ( which
die soon after being passed), and must be examined within 1 hour after
passage.

• Formed specimens may be examined at any time during the first day, but
should not be left overnight ( cyst may disintegrate).

• Excessive bulky stools may indicate conditions such as giardiasis.

MICROSCOPIC EXAMINATION

Wet mount is the simplest and easiest technique for the examination of feces, and this
method should be performed in all laboratories at peripheral level.

A wet mount can be prepared directly from fecal material or from concentrated
specimens.

The basic types of wet mount that should be used for each fecal examination are
normal saline (0.85% NaCl), iodine, and buffered methylene blue.

1. The Saline Wet Mount

 Is used for the initial microscopic examination of stool specimens.

 It is employed primarily to demonstrate worms eggs, larvae. Protozoan

trophozoites, and cysts.

 This type of mount can also reveal the presence of red blood cells and white
blood cells.

 If the presence of amoebic trophozoites is suspected, warm saline (37˚C)

should be us

2. The Iodine Wet Mount

 Is used mainly to stain glycogen and the nuclei of cysts, if present.

 Cysts can usually be specifically identified in this mount.

  Trophozoite can not be revealed by this type of wet mount, because iodine kill
trophozoite.

3. The Buffered Methylene Blue Wet Mount (BMB)

-Should be prepared each time amoebic trophozoites are seen in a saline wet mount, or
when their presence is suspected.

-BMB stains amoebic trophozoites, but not stain amoebic cysts, flagellate trophozoites
or flagellate cysts.

-BMB stain is appropriate only for fresh unpreserved specimens.

-BMB stain live organism only, it isn’t used on preserved samples in which the organism
have been killed

-Wait for five minutes to allow the stain to penetrate the trophozoites. It will overstrain
the trophozoites in 30 minutes.

 Formed stool: take the portion of stool from an area to include inside and
outside parts of the specimen.

 Stool with mucus: if mucus is present, label a second slide with the patient’s
name or number. Put a drop of saline on the slide, pick up a small portion of
mucus and mix with the saline. Trophozoites, if present, are sometimes more
readily found in mucus than in the solid parts of the stool.

 Loose watery stool: if mucus is not present, pick up a small portion of the
stool (any part) and mix with the saline.

Materials and reagents:

 Microscopic slides.

 Cover slips.

 Applicator sticks.

 Marker or pen for labeling.

 Reagents: Saline solution(isotonic)

 Lugols iodine(1% solution)

 BMB
  Wet mount procedures

EXAMINATION AND RESULTS INTERPRETATION

If no parasites are found: -“No ova, cysts or parasites seen”, and specify whether this result
was obtained by direct examination or by a concentration method (name method used).

-Never state categorically: “No parasites”

-If any parasites are seen, write the scientific name of the parasite with stages Example:
Giardia lambilia cyst