Lecture 10: Small Bowel and Colon Disorders Flashcards
What is the Bristol Stool Chart and how does Type 1 differ from Type 7?
- Type 1 is on the constipated end of the spectrum w/ stool equal to hard lumps, like nuts (hard to pass)
- Type 7 is on the diarrhea end of the spectrum and is watery w/ no solid pieces (entirely liquid)

What is the major cause of death associated with diarrhea?
Dehydration
Diarrhea for >14 days is most commonly due to a (infectious/non-infectious) cause?
Likely non-infectious —> think meds!
If a workup is indicated for acute diarrhea which serum labs should you get?
- CBC
- Electrolytes
- BUN
- Cr
- Blood culture?
Most routine (bacterial) stool cultures include which 4 organisms?
- Salmonella
- Shigella
- E. coli (ask for shiga-like toxin detection for O157:H7 EHEC)
- Most detect campylobacter (although may need to be requested)
Food poisoning from which bacteria is commonly seen after ingestion of potato salad, mayonnaise or cream pastries?
S. aureus = Gram (+) cocci
Food poisoning by which bacteria is most commonly associated with ingestion of lunch meat and unpasteurized dairy?
Listeria monocytogenes** –> **Gram (+) rod
What virulence factor does S. aureus contain that leads to the sx’s of food poisoning?
Type of diarrhea?
- Preformed enterotoxins
- Watery diarrhea

Which bacteria is associated with food poisoning from fried rice?
Type of diarrhea and what is the main symptom?
- Bacillus cereus –> Gram (+) rod
- Watery diarrhea
- Vomiting is the main symptom!

Which gram-positive spore-forming rod is associated with food poisoning as a result of consuming inadequately cooked beef, ham, poultry, legumes, or gravy?
Type of diarrhea?
- Clostridium perfringens
- Watery diarrhea
Shigella spp. food poisoning is most commonly associated with what types of food?
Potato or egg salad, lettuce, raw vegetables
What type of diarrhea and symptoms are associated with Shigella spp. food poisoning?
Begins as watery —> intense colitis w/ fever and frequent small volume stools w/ blood and pus
Shigella spp. infection will have what finding in the stool of infected pt?
Fecal leukocytes (+)
What are post-infectious complications of Shigella spp.?
- Reactive arthritis

- HUS
Complications associated with Salmonella typhimurium?
- Reactive arthritis
- Endocarditis
- Septic arthritis
- Osteomyelitis (sickle-cell pts)
Vibrio parahemolyticus is associated with food poisoning from the consumption of what?
What kind of diarrhea?
- Seafood (i.e., shellfish, oysters, shrimp)
- Watery —> bloody diarrhea
Where is Vibrio vulnificus found?
Most often infects people via what 2 routes?
Common symptoms associated with each route?
- Warm, shallow, coastal salt water
- Eating raw shellfish (oysters) –> vomiting and diarrhea
- Open wounds in the water –> bullous skin lesions

Vibrio vulnificus infections are life threatening in which patients?
- Immunocompromised
- Especially cirrhosis and hemochromatosis pts

Aeromonas hydrophila is found in which enviornments?
Most often transmitted how?
- Fresh water or brackish water (slightly salty)
- Eating fish or shellfish
- Wounded in the water or open wounds in water
Which type of diarrhea can be produced by Aeromonas hydrophila? (2 types)
- Cholera-like: watery rice water stools
- Bloody mucoid stools
If someone sustains a wound while in fresh water and then has a rapidly progressive wound infection (i.e., necrotizing fasciitis), which bacteria should be susepcted?
Aeromonas hydrophila
What are positive serum and fecal findings associated with EHEC infection?
- Peripheral leukocytes (+) - CBC
- Fecal leukocytes or lactoferrin (+)
- Stool culture = shiga-like toxin
Antibiotic therapy for EHEC increases the risk for?
HUS
Infections by Yersinia enterocolitica poses a higher risk in which patients?
- Pts w/ derangement of iron metabolism
- Iron-overload syndromes, cirrhosis, hemochromatosis, aplastic anemia, and thalassemia
Infection by which bacteria can mimic appendicitis due to its localization to the terminal ileum?
Yersinia enterocolitica
Listeria monocytogenes can infect anybody, but has a predilection for whom?
- Pregnant women
- Extremes of age
- Immunosuppressed
- Those w/ Hemochromatosis

How is C. difficile diagnosed?
Stool culture - PCR for toxin (TcdA and TcdB)
Which 4 antibiotics are most commonly associated with infection with C. difficile?
1) Clindamycin
2) Ampicillin
3) Cephalosporins (3rd gens)
4) Fluoroquinolones
Best preventative measure for minimizing transmission and infection of C. difficile in a hospital setting?
Wash hands w/ soap and water + use of disposable gloves
How is Rotavirus detected?
Characteristic finding on electron microscopy?
- Detected by viral culture PCR
- “Wagon-wheel” appearance on electron microscopy

Who is most commonly affected by Adenovirus and what are the most common symptoms?
- Children
- Fever, chills, myalgias, sore throat
- Watery diarrhea
- Conjunctivits
- Pharyngitis
How is the Dx of Strongyloides stercoralis made?
- Rhabditiform larvae in stool
- Eosinophils in stool
Which organism is the 2nd most common cause of Esophageal Varices in Africa?
What other complications?
- Schistosoma mansoni
- Bloody stools, bladder cancer, and liver cysts
Which organism can form cysts in the liver or lungs, which characteristically looks like free-flowing “hydatid sand” on CT?
Echinococcus granulosus

Which 2 bacteria are most often responsible for inflammatory diarrhea w/ fecal leukocytes and fecal lactoferrin but not typically bloody stools?
- Listeria monocytogenes
- Clostridium difficile
Anti-motility agents may be used in patients in whom no fever and non-bloody stools exist, but are not to be used if infection is due to which 2 organisms?
- C. diff
- EHEC
Chronic use of what can lead to melanosis coli, a benign hyperpigmentation of the colon?
Laxitives

The presence of abdominal pain with chronic diarrhea (>4 wks duration) suggests which 2 disorders may be present?
1) IBS
2) IBD
Before embarking on an extensive evaluation for the cause of someones chronic diarrhea the most common causes should be considered which include what 3 things?
1) Medications
2) IBS
3) Lactose intolerance
Which signs/symptoms and findings are inconsistent with the most common causes of chronic diarrhea (i.e., red flags) and warrant further evaluation?
- Presence of nocturnal diarrhea
- Weight loss
- Anemia
- Positive FOBT
Evaluation of chronic diarrhea showing a fecal elastase <100 mcg/g may point to what underlying problem?
Pancreatic insufficiency
Neuroendocrine tumors may be localized via what imaging modality?
Somatostatin receptor scintigraphy
A patient with chronic, high-volume watery diarrhea (>1L/day) with normal osmotic gap that persists during fasting should raise suspicion of which disorder?
Neuroendocrine tumor
Which non-invasive breath tests can be used for the diagnosis of small bowel bacterial overgrowth?
Glucose or lactulose or 14C-xylose breath tests
Carbohydrate malabsorption is common and should be considered in all patints with chronic, postprandial diarrhea, and can be confirmed by which tests?
- Elimination trial for 2-3 weeks
- Hyrdrogen breath tests

What are the 2 major subtypes of Microscopic Colitis?
1) Lymphocytic colitis
2) Collagenous colitis
What are some of the meds that have been implicated in Microscopic Colitis (i.e., collagenous and lymphocytic colitis)?
- NSAIDs
- PPIs
- Low-dose aspirin
- SSRIs
- AChE inhibitors
- Beta-blockers
What is the first line treatment for the diarrhea associated w/ Microscopic Colitis?
Antidiarrheal therapy w/ loperamide
What is stool osmotic gap?
What is a normal value?
- Difference between measured osmolality of the stool (or serum) and the estimated stool osmolality
- Normally <50 mOsm/kg
An osmotic gap >75 mOsm/kg implies that diarrhea is caused by what?
Ingestion or malabsorption of an osmotically active substance
A person with diarrhea that has an increased stool osmotic gap and a stool volume that decreases with fasting is a clue for what type of diarrhea?
Osmotic
In any patients with chronic, postprandial diarrhea what should alway be considered as a cause?
Carbohydrate malabsorption
What are some of the most common causes of Osmotic Diarrhea?
- CHO malabsorption (lactose, fructose, sorbitol)
- Laxative abuse = Factitious (could be osmotic or secretory)
- Medications: antacids, lactulose, etc..
High-volume watery diarrhea (>1L/day) with a normal osmotic gap is characteristic of what type?
Secretory diarrhea
What is the effect of fasting on Secretory Diarrhea?
Little change in stool output
What are some common causes of Secretory Diarrhea?
- Endocrine tumors: ZE syndrome, Carcinoid syndrome, VIPoma, Medullary thyroid carcinoma
- Bile salt malabsorption
What is one of the most common causes of chronic watery diarrhea in the elderly?
Microscopic colitis
4 characteristic signs/symptoms of Malabsorptive Conditions?
- Weight loss
- Osmotic diarrhea
- Steatorhhea
- Nutritional deficiency
The steatorrhea associated with Pancreatic Insufficiency is due to malabsorption of?
Triglycerides
Characteristic skin rash consisting of pruritic papulovesicles over the extensor surfaces of the extremities and over the trunk, scalp, and neck is a cutaneous manifestation of what malabsorptive disorder?
Celiac disease —> dermatitis herpetiformis
Recommended serological test for Celiac Disease is?
IgA tTG antibody
Which serologic test has excellent sensitivity and specificity for Celiacs disease and can be useful in pts with IgA deficiency as well as young children?
IgG anti-deaminated gliadin peptides (DGP)
What is the standard method for confirming the diagnosis of Celiacs in a patient w/ positive serologic tests?
Mucosal biopsy of prox. duodenum and distal duodenum
Why is Dual-energy X-ray densitometry scanning recommended for all patients with sprue?
Screen for osteoporosis
How is the diagnosis of bacterial overgrowth in the GI confirmed?
Jejunal aspiration w/ quantitative bacterial cultures
Bacterial overgrowth is associated with what type of diarrhea(s)?
Osmotic and secretory + increased flatulence
What are 6 of the most common causes of Short Bowel Syndrome in adults?
1) Chron disease
2) Mesenteric infarction
3) Radiation enteritis
4) Volvulus
5) Tumor resection
6) Trauma
Which factors play a role in the type and degree of malabsorption associated with Short Bowel Syndrome?
- Depend on the length and site of the resection
- Degree of adaption of the remaining bowel
Increased erythrocyte sedimentation rate or CRP in a patient with chronic diarrhea suggests which disorder?
IBD
What is the most sensitive method for detecting Giardia and E. histolytica infection?
Fecal antigen test
What does an adequate normal biopsy of a patient with suspected Celiac Disease mean?
Excludes the diagnosis
Most patients with Celiac disease also have what other deficiency?
Lactose intolerance either temporarily or permanently and should avoid dairy until intestinal symptoms improve on glute-free diet
What is the most common presenting symptom with Whipple Disease?
Others?
- Weight loss = most common
- Arthralgias = first sx’s
- Diarrhea
- Abdominal pain
Whipple disease is established (90%) by endoscopic biopsy w/ histo evaluation of which part of the GI?
Duodenum
What is the characteristic appearance of Whipple bacillus on electron microscopy?
Trilamellar wall
Resection of over 50cm vs. 100cm of the ileum will lead to what deficiencies and what type of diarrhea associated with each?
What must be done as treatment?
- >50cm = require monthly subcutanous or IM vit B12 shots; bile salt malabsorption will lead to watery diarrhea
- >100 cm = ↓ bile salt pool –> steatorrhea and ADEK deficiency. Require a low-fat diet and vitamin supplements
All of the unabsorbed fatty acids as a result of terminal ileal resection will bind to what and lead to what problem(s)?
Should be managed how?
- Bind Ca2+, decreasing its absorption and increasing absorption of oxalate —> Oxalate kidney stones
- Cholesterol gallstones due to decreased bile salts (common)
- Ca2+ supplements should be given to bind oxalate and increase serum Ca2+
What % of the small intestine can be resected and is usually well tolerated?
40-50%
Resection of the colon + 100 cm of proximal jejunum should be managed how?
Main goal?
- Maintain adequate oral nutrition
- Low-fat, high-complex CHO diet
With a full colon resection + less than 100-200cm of jejunum left, how should this pt be managed nutritionally?
NEED parenteral nutrition
Duodenal resection will lead to malabsorption of which vitamins?
Folate, iron, or calcium
What is the most common cause of chronic diarrhea in young adults + the most common GI disease in clinical practice?
IBS
What are the 3 types of clinical presentations for IBS?
- Spastic colon (chronic abdominal pain and constipation)
- Alternating constipation and diarrhea
3) Chronic, painless diarrhea
Pts presenting with IBS to a physician have an increased frequency of what type of disturbances?
Psychological –> Depression, hysteria, OCD
Patients with IBS often report relief of abdominal pain with?
Bowel movements
How long must the symptoms associated with IBS be present for a diagnosis and how long for it to be considered a differential?
Chronic > 6 months (sx’s for at least 3 mo. before considering it a differential)
When assessing a patient with IBS you need to ask about “alarm symptoms,” which include what 6 things?
- Acute onset of sx’s
- Nocturnal diarrhea
- Severe constipation or diarrhea
- Hematochezia
- Weight loss
- Fever = incompatible w/ dx of IBS
What are the 3 ROME diagnostic criteria for IBS?
- Improvement with defecation
- Onset associated w/ a change in frequency of stool
- Onset associated w/ a change in form (appearance) of stool
*Criteria filled for last 3 months with sx onset at least 6 months before diagnosis*
In patients w/ IBS that have a lot of diarrhea, bloating, and flatulence which dietary restriction should be considered to improve symptoms (hint: mnemonic)?
- Dietary restriction of “FODMAPS”
- Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols
XR or CT demonstrating colon dilation, confined to the cecum and proximal colon without signs of mechanical obstruction is consistent with what disorder?
Acute colonic pseudo-obstruction (Ogilvie Syndrome)
A cecal diameter greater than _______ cm is associated with increased risk of colon perforation and requires intervention.
A cecal diameter greater than 10-12 cm is associated with increased risk of colon perforation and requires intervention.
*Ogilvie Syndrome
How often should Cecal size be assessed with an abdominal radiograph in a patient with Acute Colonic Pseudo-Obstruction (Ogilvie Syndrome)?
Every 12 hours
What are major differences between antibiotic-associated diarrhea and antibiotic-associated colitis?
- ABx- assoc. diarrhea = most cases NOT due to C. difficile + Diarrhea typically occurs during period of ABx exposure and resolves spontaneously w/ discontinuation
- ABx-assoc. colitis = almost always due to C. difficile and sx’s can be mild to fulminant
Patients on antibiotics and what other drug in a hospital setting are at a higher risk of acquiring C. difficile and developing C. difficile-associated diarrhea?
PPIs
C. difficile should be considered in all hospitalized patients with unexplained?
Leukocytosis
Which labratory findings (i.e., WBC’s, albumin, and others) are suggestive of severe disease in patient with C. difficile?
- WBC >30,000/mcL
- Albumin <2.5 g/dL (protein-losing enteropathy)
- Elevated serum lactate
- Rising creatinine
In patients with severe C. difficile colitis what will be seen on flexible signoidoscopy?
Characteristic findings.
- True pseudomembranous colitis
- Classic “volcano” exudate of fibrin and neutrophils

Diverticulitis is best staged and confirmed with what imaging modality?
Which imaging modality is contraindicated?
- Best = CT with contrast
- Endoscopy is contraindicated during initial stages of an acute attack due to risk of perforation
Pts with weight loss, who have been experiencing a dull, crampy periumbilical pain 15-30 mins after a meal that lasts several hours and often report a “food fear” need to be evaluated for?
Chronic Mesenteric Insufficiency (aka “abdominal angina)
What is the American Cancer Society guidelines for colorectal cancer screening for all people at average risk?
- Start regular screening at age 45
- Continue screening through age 75 (screening after 75 is based on personal preferences, life expectancy, overall health, and prior screening hx)
What is the recommeded screening for CRC in a patient w/ a first-degree relative w/ CRC or adenomas diagnosed <60 yo or two first-degree relatives of any age?
Colonoscopy every 5 years, beginning at age 40 or 10 years before the age of the youngest affected relative (whichever is first)
When should screening for CRC begin in someone with FAP?
10-12 yo
When should screening for CRC begin in someone with HNPCC?
Beginning at age 20-25 yo and every 1-2 years or 10 years younger than youngest age of CRC diagnosis in family
What is a more sensitive test for CRC and advanced adenomas compared to FOBT?
FIT = fecal immunohistochemical test for hemoglobin

What are ways that colonic polyps can be identified and treated?
Which are recommended and which are not?
- Barium enema (not recommended) or CT colonography (okay, but only for low risk pt)
- Colonoscopy = best choice –> diagnostic and therapeutic (polyectomy)

What is the recommended treatment for FAP?
Prophylactic colectomy to prevent otherwise inevitable colon cancer
Lynch syndrome (aka HNPCC) is due to mutations in genes essential in?
DNA base-pair mismatches: MLH1, MSH2
The diagnosis of Lynch Syndrome (HNPCC) is suspected with what type of test/finding?
Diagnosis is confirmed via?
- Diagnosis suspected by tumor tissue immunohistochemical staining for mismatch repair proteins or testing microsatellite instability
- Confirmed by genetic testing!
For woman with Lynch syndrome (HNPCC) at age 40 or once they have finished childbearing, what is the recommended treatment?
Prophylactic hysterectomy and oophorectomy