Feces Flashcards
Fecal Formation: The digestive system
alimentary tract; accessory digestive organs
contains and processes the food and drinks from ingestion through digestion and elimination
Fecal Formation: Chyme
digestive secretions
digestive enzymes
partially digested food
water in the digestive tract
Fecal Formation: Absorption occurs along the way
water
electrolytes
nutrients
vitamins
After Chyme is in the large intestine from 3-10 hours it becomes solid or semisolid feces.
If a large volume of liquid is presented rapidly to the colon, diarrhea results.
Disorders of the Gastrointestinal Tract: Diarrhea-
common disorder of the GI tract
increased frequency and volume of bowel movements
associated with infections, toxins, malabsorption, etc.
Diarrhea can be due to
increased secretions
presence of an osmotically active substance
hypermotility with decreased absorption
Diarrhea can lead to dehydration and serious electrolyte imbalances
Malabsorption
a state of abnormal digestion or absorption of a nutrient or multiple nutrients through the GI tract may lead to malnutrition or anemia improperly digested: fats, meat fibers carbohydrates
Maldigestion
impaired digestion caused by a lack of digestive enzymes
Colorectal cancer
this cancer is associated with “occult” or hidden blood in the stool
Pancreatic insufficiency and cystic fibrosis
decreased pancreatic digestive enzymes trypsin chymotrypsin elastase I results in maldigestion The feces may be tested for the presence of these substances.
Fecal Specimen Collection
Containers must be clean, dry, sealable, and leakproof. Special collection kits are available for occult blood, culture, and ova and parasites (require preservatives).
No contamination with urine or toilet water.
Some tests require special diet modifications prior to specimen collection.
Enemas or barium sulfate can interfere with some tests.
For quantitative tests, generally a three day collection is used. In some tests, timing of the collection is important.
Gross Examination
Color- Dark brown = normal Black= old blood, upper GI Red blood = lower GI Pale (acholic)= biliary obstruction, barium sulfate Abnormal shape ribbonlike = GI tract obstruction
Microscopic Examination - leukocytes
Mucous with blood or pus or is often seen in dysentary and damage to the intestinal wall.
Leukocytes
neutrophils (in bacterial infection)
eosinophils (in amoebic infestation)
Microscopic methods to detect leukocyte
methylene blue stain and wet prep
dried smear stained with Gram’s or Wright’s stain (Wright’s stain improve cell differentiation)
Latex agglutination tests test for lactoferrin, an enzyme present in the granules of granulocytes.
Fecal Occult Blood
occult” = hidden May indicate Infections or inflammation of the GI tract Trauma Ulcers Hemorrhoids Bleeding gums Colorectal cancer The American Cancer society recommends testing on all those over age 50 years
Melena
A large amount of fecal blood
May be black, tarry stool
Lower GI tract bleeds usually bright red blood if not occult
Patients should follow the recommended diet in the days preceding the test:
Avoid red meat, fish, bananas, cantaloupe, pears, plums, turnips, horseradish, broccoli, cauliflower, aspirin, and vitamin C.
Detected by the guaiac test. Guaiac is greenish brown resin obtained from the guaiacum tree
Occult blood
Guaiac fecal occult blood test.
Add hydrogen peroxide
Fetal hemoglobin (APT Test)
Infant stool or vomitus may contain blood
Source of blood must be identified as infant or mother
Sometimes this distinction is vital to the newborn’s survival
APT test uses sample mixed with water to give a pink liquid.
Alkali (dilute sodium hydroxide) is added to supernatant
Pink color remains = fetal blood
Development of yellow or brown color = maternal blood
Fecal Fat Testing: Steatorrhea is an increase in fecal fat caused by
conditions that decrease the production of pancreatic enzymes
cystic fibrosis
pancreatic insufficiency
Pancreatitis
pancreatic carcinoma
Malabsorption caused by
bacterial overgrowth, intestinal resection
celiac disease, tropical sprue
lymphoma,
Crohn disease, Whipple disease, and giardiasis.
Fecal Fat Testing: Stool samples in steatorrhea
pale and greasy appearance
foul smelling
Prior to testing, patients must
have a diet with a normal amount of fat intake
must avoid contamination of the sample with mineral oils and creams
Fecal Fat Testing: Qualitative- two part exam
neutral fats such as triglycerides
Oil red O, Sudan III in 95% ethanol, Sudan IV
<60 small or medium sized orange-red globules/HPF is normal
soaps and fatty acids
Oil red O, Sudan III in 95% ethanol, Sudan IV
Plus acetic acid and heat the slide prior to microscopic exam.
<100 globules/HPF that are less than 4µm is normal
Fecal Fat Testing: Interpretation
A normal amount of neutral fecal fat with an increased amount of soaps and fatty acids is associated with intestinal absorption.
Increased amounts of neutral fats on the first slide is associated with maldigestion or impaired digestion leading to steatorrhea
Qualitative Fecal Fat Testing: Picture
Steatorrhea with fecal fat Sudan III stain for neutral fats.
Qualitative Fecal Fat Testing: Picture
Steatorrhea with fecal fat Sudan III stain for fatty acids.
Fecal Fat Testing:Quantitative fat testing
Usually performed in chemistry
Requires adherence to a diet of 100g/ day fat intake before and during test collection.
Forty-eight to seventy-two hour fecal collections are needed.
Meat Fibers
Creatorrhea is an increase in meat fibers.
Creatorrhea is present in malabsorption and maldigestion, especially in cystic fibrosis and in hypermotility.
Meat fibers are rectangular with cross striations.
Eosin in 10% ethanol can be used as a stain to help identify these fibers.
Creatorrhea.
Undigested meat fiber. Note the clearly defined muscle striations.
Fecal Carbohydrates in Malabsorption
Disaccharides are osmotically active and can cause the movement of a large amount of water to the intestine.
Sugars are present in
celiac disease, due to the inability to reabsorb carbohydrates
lactose intolerance
congenital disaccharidase deficiencies
diarrhea with inflammatory necrotizing enterocolitis
The Clinitest is used to detect fecal carbohydrates in infant stool samples.
A pH is also done along with the Clinitest, as when carbohydrates are present, the pH decreases from fairly neutral to below 5.5.
