Stool analysis:

A stool analysis is a series of tests done on a stool (feces)

sample for differential diagnosis of certain diseases of

digestive system.

Stool analysis procedure is divided into:

1-Physical Examination.

2-Chemical Examination.

3-Microscopic Examination.

Clinical significance of stool analysis:

1-Diagnosis of digestive system infectious diseases:

Bacteria, parasites, virus, and fungi.

2-Diagnosis of pancreas disorders (inflammation); which

associated with malabsorption of nutrients.

3-Primary screening test for some types of digestive

system malignancy such as: Colon cancer.

4-Primary screening test for peptic ulcer disease, and

some types of anemia.

For whom Stool analysis is urgently required?

1-Patients with abdominal pain.

2-Patients with diarrhea.

3-Patients with anemia.

Other situations by which Stool analysis is non-urgently

required:

1-Patients who is too thin or do not grow well.

2-Patient with stool color that is changed to abnormal color.

Stool analysis:1-Physical Examination: A-Color: Normal feces has a dark brown color.

(Bilirubin in the presence of bacteria will be

oxidized to urobilinogen which give stool its color).

Abnormal color: 1- Black color indicates blood of upper GIT origin(melena).

2- Red color indicates blood of lower GIT origin.

3- White color indicates yeast fermentation (Candida). -Very pale color indicates biliary obstruction or barium enema.

N

Physical Examination:B-Consistency:

-Normal feces is solid to semi-solid depending on diet.

-A ribbon like fecal specimen could indicate irritable bowl

syndrome or GIT obstruction.

-Liquid stool indicates diarrhea (Gastroenteritis).

-80-170 gm/day.

Chemical Examination:

1-The pH: The pH of the stool is 7.0-7.5.2-Suger contents:

The stool contains less than 0.25 grams per deciliter (g/dL) or

less than 13.9 millimoles per liter (mmol/L) of sugars.

-Elevated Suger indicates (more than 0.5g/dl):

-Lactose intolerance.

3-Fat contents:

The stool contains 2-7 grams of fat per 24 hours (g/24h).

N

- High levels of fat(steatorrhea) in the stool may be caused

by diseases such as pancreatitis, celiac disease(allergy to

Gluten protein in wheat) ,or cystic fibrosis.

4-Occult blood: (The stool guaiac test): -Occult blood can be detected chemically : 1- Paper surface with phenolic compound alpha-guaiaconic acid. 2- Stool applied to the paper. 3-Hydrogen peroxide oxidizes alpha-guaiaconic acid to dark- blue color within two seconds.

4-Heme is a catalyst of this reaction.

N

Patients should be instructed to avoid red meat, horse

raddish, Asprin, Vitamin C as they interfere with the test by

their catalases and peroxidases .

Clinical significance of the test:

1-Diagnosis of Colorectal cancer.

2-Diagnosis of ulcer hemorrhoids.

3-Invasive Gastroenteritis.

Microscopic Examination: -Fecal leukocytes, especially neutrophils are associated with dysentery. -They can be detected by dried smears of the stool stained with gram stain.-Wet-mount smear(0.9% Saline) or Iodine stained smear should be prepared for parasites identification. 1-Wet-mount smear : Show the motility of active Protozoa. 2-Iodine smear: Show the nucleus and karyosome of protozoa.

Amoebic dysentery: Entamoeba histolytica (Rhizopoda):

-Offensive stool.-Faecal matter mixed with blood and mucus.-RBCs, pus, mucus, and Entamoeba histolytica cyst or/and trophozoite (central karyosome).-Trophozoite show motility in one direction.

Giardia intestinalis :- Gastrointestinal Mastigophora.- Habitat: Small intestine especially in duodenum.- Disease: Fatty diarrhea especially in children. - Morphology: Trophozoite: four pairs of flagella.

Giardia cyst (infective and diagnostic) Giardia trophozoite (diagnostic stage).

Balantidial dysentery: Balantidium coli:

-Ciliophora. -Kidney-shaped Macronucleus. -Small micronucleus.-Ingestion of Contaminated pork meat.

Helminthes: Schistosoma mansoni:- Trematoda.- Intestinal bilharziasis.- Diagnosis: finding of ova in stool.

Ova with Lateral spine (diagnostic stage)

Cysticercosis: Taenia (Cestoda) infection:1- Taenia saginata (beef tapeworm). 2- Taenia solium (pork tapeworm).

Diagnostic stages:1-Gravid segments. 2-Hexacantho- embryonated ova.

N

Ascaris lumbricoides: -Nematoda.-Diagnostic stage: 1-Fertilized, un-fertilized ova. 2-Embryonated ova. 3-Adult stage.

N

Hook worms: - Ancylostoma duodenale.- Nematoda. - Diagnostic stage: 4-8 cell stage Embryonated ova.

N

Enterobius vermicularis: -Nematoda.-Diagnostic stage: D-shaped ova.

D-Shaped Ova.

N

• "Scotch tape test"

It is best done at night during the characteristic intense itching or early in the morning before any bathing or washing. 

Wrap a piece of cellophane tape around a tongue depressor, sticky side out, and press it to the skin around the anus to collect any eggs. 

Take the tape to a doctor, who will put it under a microscope to look for pinworm eggs.– The doctor may ask the person to use several pieces of tape to increase the

likelihood of seeing the eggs. A single specimen will detect approximately 50% of cases; 90% of cases will be detected if the test is repeated three times. 

– Blood tests are not necessary to establish the diagnosis of pinworm infection.

• The doctor may decide based upon the patient's symptoms that pinworms are present and may treat with medication without doing any tests. 

N

Strongyloides stercoralis: -Free-living Nematoda.-Diagnostic stage: Rhabditiform larvae in stool.