Analysis of Urine and Body Fluids: Fecalysis PT 2

Comprehensive flashcards covering macroscopic, microscopic, and chemical analysis of stool, including clinical significance and associated diseases.

What is the normal color range of a stool specimen?

Brown, ranging from a light shade of brown to dark brown.

What condition is suggested pathologically by clay-colored, gray, or pale yellow stool?

Biliary obstruction or post hepatic obstruction.

What is the common term used for pale or gray-colored stools in a clinical setting?

Alcoholic.

Which non-pathologic substance used as an X-ray contrast media can cause white or chalky stool color?

Barium Sulfate.

What is the primary clinical significance of Fecal Occult Blood Testing (FOBT)?

Early detection of gastrointestinal bleeding.

What two factors are routinely noted during the macroscopic physical examination of stool?

Color and consistency.

What causes bright red stool from lower GI bleeding to maintain its color?

The blood is fresh and there is minimal time for it to be degraded.

Name two types of non-pathologic causes for red-colored stool.

Ingestion of beets, food dyes, or certain drugs like Rifampin or PSP dye.

What is the clinical significance of black, tarry stool?

Upper GI bleeding.

Why does stool appear black and tarry in upper GI bleeding cases?

The hemoglobin has been degraded as it passes through the gastrointestinal tract.

Which specific medication therapy for anemic patients is a common non-pathologic cause of black stool?

Iron therapy (Ferrous sulfate).

What substance may cause green stool during antibiotic therapy?

Biliverdin.

What specific disease is characterized by 'Pea Soup' diarrhea?

Typhoid Fever.

Which pathogen is notoriously associated with 'Rice Water' diarrhea?

Cholera.

What does a narrow, ribbon-like, or flattened stool shape indicate?

Intestinal constriction or narrowing of the lumen.

What are the macroscopic characteristics of stool in steatorrhea?

Bulky, frothy, greasy, spongy, and accompanied by a strong foul odor.

Translucent gelatinous mucus clinging to the surface of formed stool is associated with what conditions?

Spastic constipation or mucous colitis.

Bloody mucus clinging to the fecal mass may indicate which two conditions?

Neoplasms or inflammatory processes of the rectal canal.

In which two conditions is mucus commonly associated with both pus and blood?

Ulcerative Colitis and Bacillary Dysentery (Shigellosis).

What condition is characterized by the secretion of a copious quantity of mucus?

Villous adenoma of the colon.

What is the normal quantity range for stool produced per day?

$100$ to $200\,g/day$.

What is the normal pH value range for fecalysis?

$7.0$ to $8.0$.

What type of white blood cell is primarily evaluated during fecal leukocyte analysis to investigate the cause of diarrhea?

Neutrophils.

The presence of at least how many neutrophils per HPF is indicative of invasive bacteria in the stool?

$3$ neutrophils/HPF.

Name four invasive bacteria that typically cause the presence of fecal leukocytes.

Salmonella, Shigella, Campylobacter, and Yersinia.

Which category of bacteria, including S. aureus and Vibrio spp., results in an absence of fecal neutrophils?

Toxin-producing bacteria.

What stain is added to a stool suspension for a faster (though harder to interpret) wet preparation of fecal leukocytes?

Methylene blue.

Which two stains are used in a dried preparation to provide permanent slides for fecal leukocyte evaluation?

Wright’s or Gram Stain.

What is the function of Lactoferrin in the immune system?

It is an iron-binding protein that competes with bacteria for essential iron.

What is the major advantage of the Lactoferrin Latex Agglutination Test (LLAT) over traditional microscopy?

It remains sensitive in refrigerated and frozen specimens.

The presence of muscle fibers in the stool is helpful in monitoring patients with which deficiency?

Pancreatic insufficiency (as seen in Cystic Fibrosis).

Define a Gastrocolic Fistula.

A condition where a non-functioning part of the GIT connects to another part, forming an abnormal passage.

How many undigested muscle fibers must be present to be reported as an 'increased' finding?

Greater than $10$.

What microscopic feature defines an undigested muscle fiber?

Visible muscle striations in two directions (horizontal and vertical).

How is a partially digested muscle fiber distinguished from a digested fiber?

A partially digested fiber has striations in only one direction, while a digested fiber has no striations.

What reagent is used to enhance the visibility of muscle fiber striations during microscopy?

$10\%$ Alcoholic Eosin.

Which staining dye is most routinely used for qualitative screening of fecal fats?

Sudan III.

Which specific type of fecal fat can take up Sudan III dye directly?

Triglycerides (neutral fats).

What is the microscopic appearance of triglycerides when stained with Sudan III?

Large orange or red droplets.

What is the purpose of the split fat stain (second slide) in qualitative fecal fat testing?

To observe total fats, including fatty acids and soaps.

Why is acetic acid and heat required for staining fatty acids and soaps?

To acidify and hydrolyze the fats so they can take up the stain.

In split fat staining, what droplets size per HPF is considered normal?

Less than $100$ droplets with a diameter of $<4\,\mu m$ per HPF.

What finding in split fat staining is indicative of steatorrhea?

$100$ or more fat droplets with a diameter of $6$ to $75\,\mu m$ per HPF.

According to the 'mAl dAB' mnemonic, what is indicated if fecal fat is increased on the first slide?

Maldigestion.

According to the 'mAl dAB' mnemonic, what is indicated if fecal fat is increased on the second slide (split fat)?

Malabsorption.

How is cholesterol identified in structural fecal fat microscopy?

By heating, adding Sudan III, and observing the formation of crystals once the slide cools.

What is the 'Gold Standard' for fecal fat testing?

Quantitative Fecal Fat Testing.

What are the collection and storage requirements for quantitative fecal fat testing?

A $3$-day specimen collected in a pre-weighed container and refrigerated.

Which titration method is most routinely used for quantitative fecal fat analysis?

Van de Kamer titration.

What is the fat retention threshold for diagnosing steatorrhea in adults using the Acid steatocrit test?

Greater than $31\%/day$.

define Melena.

Large amounts of fecal blood ($50$ to $100\,mL/day$) that turn the stool black and tarry.

What is the principle behind the Guaiac-Based FOBT (gFOBT)?

The Pseudoperoxidase activity of hemoglobin.

Which chromogen is most preferred for FOBT screening because it is the least sensitive and avoids false positives?

Gum-guaiac.

What is the recommended screening age for routine FOBT in the United States?

$50$ years old.

What color indicates a positive result in a Guaiac-Based FOBT?

Blue.

Name three substances that must be avoided for three days prior to gFOBT to prevent clinical interference.

Red meat (myoglobin), Vitamin C, and Aspirin/NSAIDs.

Which FOBT method uses an anti-human antibody specific for the globin portion of hemoglobin?

Immunochemical FOBT (iFOBT).

Why is iFOBT more sensitive to lower GI bleeding than upper GI bleeding?

The hemoglobin in the lower GI is less degraded and remains immunochemically active.

Which FOBT method is most sensitive to upper GI bleeding?

Porphyrin-Based FOBT.

Decreased production of which fecal enzymes is associated with chronic pancreatitis and cystic fibrosis?

Trypsin, Chymotrypsin, and Elastase I.

What is the property of fetal hemoglobin (HbF) that is utilized in the APT test?

It is highly resistant to alkaline conditions (lysing by sodium hydroxide).

In the APT test, what color indicates the presence of adult hemoglobin (HbA)?

Yellow-brown.

What concentration of sodium hydroxide is used in the APT test procedure?

$1\%$ sodium hydroxide.

Fecal carbohydrate testing is most valuable in assessing which clinical case?

Infant diarrhea.

What enzyme deficiency causes lactose intolerance?

Lactase deficiency.

What inherited disorder of carbohydrate metabolism can cause severe mental retardation and is part of newborn screening?

Galactosemia.

Which inflammatory bowel disease involves Peyer’s patches and causes the intestinal wall to thicken and stiffen?

Crohn’s disease.

Define Gluten Enteropathy (Celiac Disease).

Malabsorption in the small intestine due to gluten, which destroys epithelial cells and blunts intestinal villi.

How does Vibrio cholerae (Cholera) toxin affect the GI tract?

It stimulates adenylate cyclase to produce cAMP, causing active secretion of $Na$ and $Cl$ and inhibiting reabsorption.

How does the Shiga toxin from Shigella kill intestinal epithelial cells?

It inactivates the $60S$ ribosome, thereby inhibiting protein synthesis.