Gross Examination of Stool and Stool Color

Gross Examination of Stool

• The gross examination of stool can help with diagnosing intestinal disorders.
• Carefully observing the stool's color aids in preliminary diagnosis.
• Gross examination provides an opportunity to recover tapeworm proglottids or adult roundworms.

Stool Color

• Normal stool is brown.
• The presence of blood in stool is abnormal.

Conditions Influencing Stool Color

• Black stool can be caused by:
  • Ingestion of iron, bismuth, or charcoal (non-pathologic)
  • Bleeding in the upper gastrointestinal tract (pathologic)
• Gray stool can be caused by:
  • Chocolate or cocoa ingestion (non-pathologic)
  • Steatorrhea (mushy stool) (pathologic)
• Light gray stool can be caused by:
  • Diet high in milk products or barium ingestion (non-pathologic)
  • Bile duct obstruction or jaundice (pathologic)
• Green stool means a diet high in green vegetables (non-pathologic)
• Yellow-green stool from ingesting a diet high in vegetables and spinach (non-pathologic)
• Red stool may appear if there is a diet high in beets (non-pathologic) or bleeding in the lower gastrointestinal tract (pathologic).
• Yellow stool results from starchy foods (non-pathologic) or bilirubin (pathologic)
• Clay-colored stool may indicate an absence or reduction of bile or the presence of barium sulfate.

Stool Odor

• Stool odor is typically not included in fecalysis.
• The odor is derived from indole and skatole, which are degradation products of proteins.

Mucus in Stool

• Mucus appears as a translucent gelatinous material on the stool's surface.
• Mucus is produced by the colonic mucosa in response to parasympathetic stimulation.
• Mucus presence is observed in severe constipation and mucous colitis.

Stool Consistency

• Hard stool: Cannot be punctured with an applicator stick.
• Formed stool: Maintains shape and can be punctured with an applicator stick.
• Semi-formed stool: The bottom side fattens in the container.
• Soft stool: Can be cut using an applicator stick.
• Mushy stool: Can be reshaped with an applicator stick, has fluffy pieces with pudding-shaped consistency.
• Loose stool: Stool shapes to the container
• Diarrheic stool: Flows slowly out of the container.
• Watery stool: Fluid-like and pours out of the container.
• Narrow-ribbon like stool: spastic bowel or rectal stricture, narrowing, or obstruction of the lower colon: tumor.
• Sticky, black, tarry stool: upper gastrointestinal tract hemorrhage.

Wet Mount/Direct Fecal Smear

• The wet mount is a simple and efficient procedure for examining feces.
• Examine immediately after preparation to prevent evaporation.
• Preservation for several hours with petroleum jelly and paraffin or nail polish.
• It is recommended for detecting motile trophozoites in liquid/diarrheic specimens.
• It is also helpful to detect protozoan trophozoites and determine cellular morphology.

Materials

• Microscope
• Clean glass slide
• Coverslip
• Normal Saline Solution (NSS) / 0.85% NaCl Solution
• Stool sample
• Applicator stick
• Marking pens

Procedure

• On a clean glass slide, place a drop of NSS.
• Use an applicator stick to pick about 2 mg of feces.
• Mix with the reagent to the point where the feces should be thoroughly comminuted in a drop so that a uniform suspension will spread evenly to all edges of the coverslip.
• Cover with a coverslip and exclude bubbles.
• Examine the entire preparation systematically under the microscope using the low power objective.
• Confirm the parasites by switching to high power objectives.
• A good smear allows ordinary newspaper print to be legible through the preparation or test media while too thick of a smear will make microscopic observation difficult

Reporting Results

• Helminths:
  • POSITIVE: Number of Eggs with the name / coverslip or in plusses.
  • NEGATIVE: No Ova Seen
• Protozoa:
  • POSITIVE: Positive for the name of protozoa and the stage.
  • NEGATIVE: None Seen