General Stool Examination and Composition

General Stool Examination

• Examines stool for presence of protozoa and helminthes larvae or eggs
• Protozoa stages found in stools: Trophozoites and cysts
• Helminthes stages found in stools: Eggs and larvae

Stool Composition

• Composition:
  • 75% water
  • 25% solid
  • Solid components:
    • Undigested and unabsorbed food
    • Intestinal secretions, mucous
    • Bile pigments and salts
    • Decomposed products
    • Bacteria
    • Inorganic material
    • Epithelial cells, leukocytes

Precautions Before Stool Collection

• Avoid the following for 48 hours prior to collection:
  • Mineral oils
  • Bismuth
  • Non-absorbable anti-diarrheal drugs
  • Antimalarial drugs
  • Antibiotics
  • Barium swallow examination
• Avoid the following for 48 hours prior to stool collection for occult blood:
  • Iron-containing drugs
  • Meat
  • Fish

Stool Collection Procedure

• Provide the patient with:
  • A plastic cup or box with a light-fitting lid
• Instructions for the patient:
  • Pass the stool specimens directly into the container
  • Label the container with:
    • Patient’s name or number
    • Date of collection
    • Time the patient passed the stool
• Minimum quantity needed for examination: The size of a pigeon’s egg

Stool Color

• Black color indicates:
  • Iron medication for anemia treatment
  • Upper gastrointestinal (GIT) bleeding (e.g., peptic ulcer, stomach carcinoma, esophageal varices)
• Bright red color (Hematochezia) indicates:
  • Lower GIT bleeding (e.g., piles, anal fissure)
• Clay color (gray-white) indicates:
  • Obstructive jaundice
• Pale brown or pale yellow color with greasy consistency indicates:
  • Malabsorption of fat (often with offensive odor)
• Yellow-green color occurs in:
  • Breast-fed infants who lack normal intestinal flora
• Red brown color indicates:
  • Drugs like Tetracyclines and Rifambicin antibiotics

Stool pH

• Normal: Neutral (pH 6.9 to 7.2)
• pH dependent on: Bacterial fermentation and putrefaction in the bowel
• Alkaline pH indicates: Excess protein ingestion
• Acidic pH indicates: Excess carbohydrate ingestion

Stool Consistency

• Can be described as:
  • Formed
  • Soft
  • Loose
  • Liquid (watery)

Blood & Mucus in Stool

• Large amounts of blood in stool suggest:
  • Bleeding piles
  • Contamination with menstrual blood
  • Destruction of a blood vessel by an ulcerative process
• Blood may be present in conditions like:
  • Colitis
  • Schistosomiasis
  • Uremia
  • Cancer
• Occult blood:
  • Undetectable macroscopically
  • Present in conditions of occult hemorrhage in the gastrointestinal tract

Microscopic Examination

• Clinical significance:
  • Identifies pathogenic parasites excreted in stool
  • Supports diagnosis of intestinal parasitic infection, often accompanied by symptoms like anemia, eosinophilia, diarrhea, and malabsorption
• Microscopic tests:
  • Normal saline mount:
    • Uses 10X and 40X objective
    • Reports the number seen in the entire preparation:
      • Scanty (rare) n1-3
      • 3-10 (+)
      • 10 to 20 (++)
      • 20 to 40(+++),
      • More than 40(++++).
  • Lugol's Iodine:
    • Staining technique for detecting parasites in stool
    • Preparation:
      • Mix 2g potassium iodide with 200 ml water until fully dissolved.
      • Add 1g iodine to the potassium iodide solution.
    • Procedure:
      • Label a slide with patient name or lab number.
      • Place one drop of normal saline on the left half of the slide.
      • Place one drop of Lugol's iodine on the right half of the slide.
      • Mix a small piece of stool with the iodine drop on the right half of the slide.
      • Use 10X and 40X objective for saline preparation.
  • Buffered Methylene Blue (BMB) mount:
    • Prepare if amoebic trophozoites are seen in the saline mount
    • Stains amoebic trophozoites only.

General Stool Examination (G.S.E.) Report

• Macroscopic examination:
  • Color: brown, yellow, green, black, etc.
  • Consistency: formed, loose, soft, watery, etc.
  • Blood or mucus
  • Occult blood
  • pH
  • Others
• Microscopic examination:
  • Pus
  • RBC
  • Parasites
  • Yeast.

This quiz covers the essential aspects of general stool examination, including the identification of protozoa and helminthes, as well as the composition of stool. It also outlines important precautions and the correct procedure for stool collection. Test your knowledge and understanding of these vital concepts in medical diagnostics.