Fecalysis

• FECES


  • contains bacteria, cellulose, and other un-digested foodstuffs, GIsecretions, bile pigments, cells, electrolytes, and water.
  • Around 100-200g of stool is passed per day
  • • Human Feces contains around 75% water and 25% solids.
• Fecal specimen analysis


  is seen as a necessary task in laboratories despite being considered unpleasant. However, it provides important diagnostic information about various health conditions related to the gastrointestinal system. This analysis involves examining the feces for signs of bleeding, liver issues, digestion problems, pancreatic diseases, inflammation, and causes of diarrhea. It's also important for detecting harmful bacteria, viruses, and parasites, although those procedures are typically covered in microbiology textbooks and not discussed here.
• Stool specimen collection


  Clean, leak-proof, screw-capped container with a spoon attached to the cap.

  • Patients should be instructed to collect the specimen in a clean container, such as a bedpan or disposable container, and transfer the specimen to the laboratory container.

  • The stool sample must not be contaminated with urine or paper towel which may contain chemical disinfectants or deodorizers that can interfere with the result.
• Stool specimen collection

  QUALITATIVE TESTING- A random specimen is suitable for qualitative testing for blood and microscopic examination of leukocytes muscle fibers, and fecal fats are usually collected in plastic or glass containers with screw-tops similar to those used for urine specimens

  •Material collected on a physician’s glove and samples applied to filter paper in occult blood testing kits are also received
• Macroscopic stool characteristics: Brown


  Normal

  urobilin or stercobilin - cause of the normal color
• Macroscopic stool characteristics: Black or Melena


  Upper GI bleeding, Iron Therapy, Charcoal, Bismuth
• Fecal Sample Size

  Pea-sized only
• Macroscopic stool characteristics: Red or Hematochezia


  Lower GI bleeding, beets and food coloring, rifampin
• Macroscopic stool characteristics: Pale yellow, white, gray


  Bile duct obstruction, Barium sulfate
• Macroscopic stool characteristics: Green 


  Oral antibiotics, green vegetables
• Macroscopic stool characteristics: Blue


  Prussian blue, grape soda
• Macroscopic stool characteristics: Violet/Purple


  Porphyria
• Macroscopic stool characteristics: Bulky/Frothy


  Bile duct obstruction, pancreatic d/o, steatorrhea
• Macroscopic stool characteristics: Butter-like


  Cystic fibrosis (Inc. mucus)
• Macroscopic stool characteristics: Mucus, blood-streaked mucus 


  Colitis, dysentery, malignancy, constipation
• Macroscopic stool characteristics: Ribbon-like 


  Intestinal constriction
• Macroscopic stool characteristics: Rice watery 


  Cholera
• Macroscopic stool characteristics: Pea-soup


  Typhoid fever
• Macroscopic stool characteristics: Scybalous (Goat droppings) 


  Constipations
• Fecal Leukocytes


  Neutrophils seen in the feces in conditions that affect the intestinal mucosa, such as ulcerative colitis and bacterial dysentery
• Fecal Leukocytes


  • Used as a preliminary test to determine whether diarrhea is being caused by invasive bacterial pathogens including Salmonella, Shigella, Campylobacter, Yersinia, and enteroinvasive E. coli
  • Bacteria that cause diarrhea by toxin production, such as Staphylococcusaureus and Vibrio spp., viruses, and parasites usually do not cause theappearance of fecal leukocytes
• Examining fecal specimens

  1. As wet preparations stained with methylene blue

  2. As dried smears stained with Wright's or Gram stain
• >/-_ Neutrophils/hpf = invasive condition
• METHYLENE BLUE STAIN FOR FECAL LEUKOCYTES


  1. Place mucus or a drop of liquid stool on a slide.
  2. Add two drops of Löffler methylene blue.
  3. Mix with a wooden applicator stick.
  4. Allow to stand for 2 to 3 minutes.
  5. Examine for neutrophils under high power.
• Steatorrhea


  Increased Fats in stool
• Creatorrhea


  Increased muscle fibers in stool
• MUSCLE FIBERS


  Patients should be instructed to include red meat in their diet beforecollecting the specimen

  • Undigested striated muscle fibers can be helpful in diagnosing and monitoring patients with pancreatic insufficiency, such as in cases of cystic fibrosis

  • May also be seen in biliary obstruction and gastrocolic fistulas
• MUSCLE FIBERS

  Slides for muscle fiber detection are prepared by emulsifying a small amount of stool in 10% alcoholic eosin, which enhances the muscle fiber striations. The entire slide is examined for exactly 5 minutes, and the number of red-stained fibers with well-preserved striations is counted

  • Only undigested fibers are counted, and the presence of more than 10 is reported as increased
• MUSCLE FIBERS


  1. Emulsify a small amount of stool in two drops of 10% eosin in alcohol.
  2. Apply cover slip and let stand for 3 minutes.
  3. Examine under high power for 5 minutes.
  4. Count the number of undigested fibers.
• FECAL FATS


  • Specimens from suspected cases of steatorrhea can be screened microscopically for the presence of excess fecal fat (steatorrhea).

  • Neutral fats (triglycerides), fatty acid salts (soaps), fatty acids, and cholesterol
• FECAL FATS


  Their presence can be observed microscopically by staining with the dyes Sudan III, Sudan IV, or oil red O; Sudan III is the most routinely used.

  • Neutral fats are readily stained by Sudan III and appear as large orange-red droplets, often located near the edge of the cover slip.
• FECAL FATS

  Observation of more than 60 droplets/high- power field can indicate steatorrhea crystals that can be identified microscopically.

  • Soaps and fatty acids do not stain directly with Sudan III

  • Normal specimens may contain as many as 100 small droplets, less than 4 μm in diameter, per high-power field.

  • 100 droplets measuring 6 to 75 μm is increased and commonly seen in steatorrhea.

  • Cholesterol is stained by Sudan III after heating and as the specimen cools forms
• NEUTRAL FAT STAIN

  1. Homogenize one part stool with two parts water.
  2. Mix emulsified stool with one drop of 95% ethyl alcohol on the slide.
  3. Add two drops of saturated Sudan III in 95% ethanol.
  4. Mix and apply the cover slip.
  5. Examine under high power.
  6. Count the orange droplets per high- power field
• SPLIT FAT STAIN

  1. Mix emulsified stool with one drop of 36% acetic acid.
  2. Add two drops of saturated Sudan III.
  3. Mix and apply the cover slip.
  4. Heat gently almost to boiling.
  5. Examine under high power.
  6. Count and measure the orange droplets per high power field.
• Guaiac-Based Fecal Occult Blood Tests

  • The most frequently used screening test for fecal bloodis the guaiac-based test for occult blood (gFOBT) based on detecting the pseudoperoxidase activity of hemoglobin.

  To prevent the presence of dietary pseudoperoxidases in the stool, patients should be instructed to avoid eating red meats, horseradish, melons, raw broccoli, cauliflower, radishes, and turnips for 3 days before specimen collection.
• Guaiac-Based Fecal Occult Blood Tests Positive

  Blue
• Aspirin and NSAIDs

  other than acetaminophen should not be taken for 7 days before specimen collection to prevent possible GI irritation.
• Vitamin C and iron supplements containing vitamin C

  should be avoided for 3 days before collections, because ascorbic acid is a strong reducing agent that interferes with the peroxidase reaction, causing a false-negative result
• Commercial testing kits:

  The kits contain guaiac- impregnated filter paper enclosed in a cardboardslide, to which the fecal specimen and hydrogen peroxide are added. Two or three filter paper areas are provided for application of material taken from different areas of the stool. Adding hydrogen peroxide to the back of the filter paper slide that contains stool produces a blue color withguaiac reagent when pseudoperoxidase activity is present.
• FALSE-POSITIVE RESULT


  • Aspirin and anti-inflammatory medications

  • Red meat

  • Horseradish

  • Raw broccoli, cauliflower, radishes, turnips, Melons

  |• Menstrual and hemorrhoid contamination