Stool analysis:

1. 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.

2. 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.

3. 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.

4. Stool analysis: 1-Physical Examination: A-Color:Normal feces hasa 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.

5. 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.

6. 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).

7. N High levels of fat(steatorrhea) in the stool may be caused by diseases such as pancreatitis, celiacdisease(allergy to Gluten protein in wheat) ,or cysticfibrosis. 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-Hydrogenperoxide oxidizes alpha-guaiaconic acid to dark- blue color within two seconds. 4-Heme is a catalyst of this reaction.

8. 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.

9. 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.

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

11. 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).

12. Balantidial dysentery: Balantidiumcoli: -Ciliophora. -Kidney-shaped Macronucleus. -Small micronucleus. -Ingestion of Contaminated pork meat.

13. Helminthes: Schistosoma mansoni: Trematoda. Intestinal bilharziasis. Diagnosis: finding of ova in stool. Ova with Lateral spine (diagnostic stage)

14. Cysticercosis: Taenia(Cestoda) infection: 1-Taeniasaginata(beef tapeworm). 2- Taeniasolium(pork tapeworm). Diagnostic stages: 1-Gravid segments. 2-Hexacantho- embryonated ova.

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

16. N Hook worms: Ancylostomaduodenale. Nematoda. Diagnostic stage: 4-8 cell stage Embryonated ova.

17. N Enterobius vermicularis: -Nematoda. -Diagnostic stage: D-shaped ova. D-Shaped Ova.

18. 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. 

19. N Strongyloidesstercoralis: -Free-living Nematoda. -Diagnostic stage: Rhabditiform larvae in stool.