McgOWan 2 Flashcards
What are the 4 causes of diarrhea in general?
infectious, malabsorption disorder, inflammatory disorder, medication induced
What is the definition of diarrhea? (timing)
either: 3 or more loose/watery stools per day OR decrease in consistency and increase in frequency of BMs of individual
What is the timing of acute, subacute, and chronic diarrhea?
acute: less than 2 weeks; subacute: 15 days-4 weeks; chronic: >4 weeks
A greasy malodorous stool may suggest what?
a malabsorption disorder
Stool containing blood or pus may suggest what?
inflammatory disorder
watery stool may suggest what?
a secretory process
The presence of abdominal pain with diarrhea could suggest what?
irritable bowel syndrome or inflammatory bowel disease
When evaluating a patient with diarrhea, what lab/chemistry is important to look at and why?
the electrolytes; the patient could lose bicarbonate and potassium (hypokalemia); the patient could be dehydrated
what stool studies would you obtain in a patient with diarrhea? and what do they tell you?
stool culture; C. Diff toxin; Fecal lactoferrin (indicates intestinal inflammation; fecal calprotectin (correlates with histologic inflammation)
What is in your DDx for non-infectious diarrhea?
antibiotic associated diarrhea
What are the characteristics associated with antibiotic associated diarrhea? (4)
usually mild/self-limited; non-inflammatory; watery; occurs during the period of antibiotic exposure (resolves spontaneously after discontinuation of the antibiotic)
What are the diagnostics used for abx associated diarrhea?
it does not require any specific laboratory evaluation or treatment; if stool examination is done however: reveals no fecal leukocytes, and stool cultures reveal no pathogens
What are the three most common causes of chronic diarrhea?
medications, IBS, or lactose intolerance
How do you obtain/calculate the osmotic gap?
you obtain stool electrolytes: osmotic vs. secretory
What stool/”fecal” diagnostic test do you get to check for malabsorption?
qualitative staining for fat (sudan stain) or fecal elastase (low)
What stool/ “fecal” tests suggests IBD?
leukocytes, calprotectin, lactoferrin
There are 2 different types of chronic diarrhea- what are they?
secretory or osmotic
How is osmotic diarrhea different from secretory diarrhea?
Osmotic: increased stool osmotic gap and diarrhea gets better with fasting; secretory: normal stool osmotic gap and diarrhea does not get better with fasting
What are the protozoans most commonly associated with chronic diarrhea?
Giardia and E. histolytica
what are the intestinal nematodes most commonly associated with chronic diarrhea?
strongyloidiasis stercoralis (endemic regions + eosinophilia)
what are the bacterial infections most commonly associated with chronic diarrhea?
C difficile
In immunocompromised patients/AIDS- what are the most common viral causes of chronic diarrhea?
CMV and HIV
in immunocompromised patients/ AIDS- what are the most common bacterial causes of chronic diarrhea?
clostridium difficile, mycobacterium avium complex
in immunocompromised patients/ AIDS- what are the most common protozoal causes of chronic diarrhea?
cryptosporidium
What are 6 DDx considerations for chronic osmotic diarrhea?
medications, IBS, lactase deficiency/intolerance, chronic infections, malabsorptive conditions, pseudodiarrhea/overflow (stool) incontinence/ fecal impaction
What associated symptoms of chronic diarrhea are not consistent with the 3 most common causes and warrant further evaluation? (4)
nocturnal diarrhea, weight loss, anemia, or positive results on fecal occult blood test (FOBT)
What are 5 medications that are known to cause chronic diarrhea?
metformin, cholinesterase inhibitors, SSRIs, NSAIDs, allopurinol
What is occurring in IBS and what is the result of this?
visceral hyperalgesia to mechanoreceptor stimuli–> altered colonic and small intestine motility at rest and in response to stress, cholinergic drugs, cholecystokinin; enhanced visceral sensation (lower pain threshold in response to gut distention)
when might IBS present?
post-infectious (after an episode of gastroenteritis)
What 3 things characterize IBS?
altered bowel habits (constipation, diarrhea, alternating); abdominal pain (crampy, lower); Absence of detectable organic pathology (diagnosis of exclusion)
What are some associated findings seen in patients with IBS?
pasty stools, ribbony or pencil-thin stools, heartburn, bloating, back pain, weakness, faintness, palpitations, and urinary frequency
How do you make the diagnosis of IBS?
considered chronic is symptoms more than 6 months (symptoms for at least 3 months is when you can consider it); it is a clinical diagnosis; utilize the ROME criteria; rule out other things with sigmoidoscopy and barium radiographs
how do you treat IBS?
low foodmap diet (avoid fatty foods and caffeine); patients presenting with IBS to a physician have an increased frequency of psychological disturbances (depression, hysteria, OCD)
What are the alarm features associated with chronic diarrhea?
acute onset, nocturnal diarrhea, severe constipation or diarrhea, hematochezia/ FOBT; weight loss, fever, FH of cancer/IBD/celiac
What causes secondary lactase deficiency?
GI disorders that affect the proximal small intestine mucosa–> crohn dx, celiac dx, and viral gastroenteritis
How is the diagnosis of lactase deficiency confirmed?
diagnosis confirmed by hydrogen breath test
Patients who chose to restrict or eliminate milk products may have increased risk of what?
osteoporosis
What is C. diff?
an anaerobic, gram-positive, spore-forming bacillus
what toxins are associated with c. diff?
cytotoxin (A&B) (exotoxin mediated)
Who is at high risk of c. diff infection? (5)
elderly/debilitated/immunocompromised; hospitalized for more than 3 days; those on multiple abx or prolonged abx; PPI use; those with IBD
what antibiotics most commonly cause c. diff?
ampicillin, clindamycin, third-generation cephalosporins, fluoroquinolones
How does c. diff present?
mild to moderate greenish, foul-smelling watery diarrhea 5-15 times per day; not typically bloody: only if associated with IBD [UC]
how do you diagnose c. diff?
stool for C. diff toxins (PCR); leukocytosis (>15k); flexible sigmoidoscopy with biopsy
what does a flexible sigmoidoscopy with biopsy show in a patient with c. diff?
pseudomembranous colitis: yellow adherent plaques; biopsy shows: epithelial ulceration with classic “volcanic” exudate of fibrin and neutrophils
How do you treat c. diff (medication wise)?
PO/IV metronidazole; PO vancomycin, fidaxomicin, fecal transplant
What are the complications associated with c. diff?
toxic megacolon/hemodynamic instability–> perforation–> death
What could cause malabsorption syndromes?
small bowel mucosal disorders
what are 5 examples of small bowel mucosal disorders that lead to malabsorption?
crohn disease, celiac sprue, lactase deficiency, whipple disease, and small bowel resections (short bowel syndrome or bile salt malabsorption)
What are the characteristics of malabsorptive syndromes? (4)
weight loss, osmotic diarrhea, steatorrhea, nutritional deficiency
Significant diarrhea without weight loss is not likely to be due to what?
malabsorption
What is the effect of gluten in diet of a celiac?
diffuse damage to the proximal small intestinal mucosa with malabsorption of nutrients
What is the humoral immune response seen in celiac disease?
antibodies to gluten, tissue transglutaminase (tTG)
what happens when a celiac takes gluten out of their diet?
levels of all antibodies become undetectable after 3-12 months of dietary gluten withdrawal
What does an endoscopy with duodenal biopsy show in a patient with celiac’s disease?
atrophy or scalloping of the duodenal folds may be observed; histology shows hypertrophy of the intestinal crypts and blunting or complete loss of intestinal villi
What screening is recommended in all patients with celiac’s?
dual-energy x-ray densitometry scanning is recommended in all patients with celiacs to screen for osteoporosis (secondary prevention)
Where are bile salts reabsorbed?
in the terminal ileum
what can lead to insufficient intraluminal bile salts?
resection or disease of this area (e.g. crohn disease)
How does bile salt malabsorption present?
mild steatorrhea, minimal weight loss, gaseous distention and flatulence, large greasy foul smelling stools
what is common in bile salt malabsorption? (complications)
impaired absorption of fat-soluble vitamins (ADEK)
what does impaired absorption of fat-soluble vitamins (ADEK) result in?
bleeding tendencies, osteoporosis, and hypocalcemia
What type of diarrhea does bile salt malformation cause?
watery secretory diarrhea
How do you treat bile salt malabsorption?
treat the underlying cause; therapeutic trial with a bile acid-binding resin such as cholestyramine
What is whipple disease and what causes it?
a rare multi-system disease; infections with the gram positive bacillus, not acid fast, Tropheryma whipplei
How does whipple disease present?
weight loss, malabsorption, (hypoalbuminemia–> peripheral edema), chronic diarrhea, fever, hypotension, LAD, arthralgias, dementia, lethargy, nystagmus
How do you diagnose whipple disease?
endoscopy with duodenal biopsy: periodic acid schiff (PAS)- positive macrophages with characteristic bacillus
what is the treatment for whipple disease?
goal is to prevent progression; antibiotic therapy–> prolonged treatment for at least 1 year is required; drugs that cross the BBB are preferred
what is the prognosis of untreated whipple disease?
it is fatal
What is overflow diarrhea? and who is at risk?
severe constipation–> only contents that get by is liquid; elderly/nursing home patients
how do you make the diagnosis of overflow diarrhea?
if there is fecal impaction that is readily detectable by rectal examination
what is pseudo-diarrhea?
frequent passage of small volumes of stool
what is pseudo-diarrhea often associated with?
rectal urgency, tenesmus, or a feeling of incomplete evacuation; accompanies IBS or proctitis
What are the complications associated with constipation?
fecal impaction and stercoral ulcers
What is the clinical presentation of fecal impaction?
decreased appetite, nausea and vomiting, abdominal pain and distention, there may be paradoxical diarrhea as liquid stool leaks around the impacted feces: overflow incontinence
how do you diagnose fecal impaction?
DRE: firm feces are palpable in rectal vault
What are the complications associated with chronic laxative use?
melanosis coli: a benign hyperpigmentation of the colon
What are the risk factors for AAA?
atherosclerosis, male sex, smoking, age, HTN, FH
What does aneurysmal pain usually mean?
it is usually a harbinger of rupture and represents a medical emergency
How do you diagnose an AAA?
abdominal ultrasound
How do you prevent AAA/ who should get this screening?
abdominal ultrasound in male sex, 65-75 years who have ever smoked; or siblings/offspring of persons with AAA
What is the management of an AAA?
monitor yearly: the risk of rupture increases with the size of the aneurysm –> aneurysms >5 cm in diameter
How does an AAA rupture present?
without any prior warning, is always life threatening; acute pain and hypotension–> requires and emergency operation
How does an aortic dissection present?
creates a false lumen (seen on CT), atypical “tearing” chest pain, widen mediastinum, vital signs abnormal
How is appendicitis initiated?
by obstruction of the appendix by a fecalith, inflammation, foreign body, or neoplasm
Besides surgery, how do you treat appendicitis?
broad-spectrum antibiotics with gram-negative and anaerobic coverage
What are the complications associated with appendicitis?
gangrene; perforation leading to abscess usually in the pelvis or suppurative peritonitis (secondary peritonitis)
what are some atypical presentations of appendicitis?
elderly–> minimal vague symptoms; pregnancy: random areas due to displacement of appendix due to uterus
What are the risk factors for ectopic pregnancy?
pelvic inflammatory disease, ruptured appendix, and prior tubal surgery
How do you diagnose an ectopic pregnancy?
positive pregnancy test: failure of serum beta-hCG to double every 48 hours; no intrauterine pregnancy on transvaginal ultrasound with elevated serum beta-hCG
What is ovarian torsion associated with?
ovarian enlargement
Which side do 70% of ovarian torsions occur on? Why?
right side: increased length of utero-ovarian ligament on right; the sigmoid on left limits space
How do ovarian torsions present?
sudden onset, severe, unilateral, lower abdominal pain that may develop after episodes of exertion
What is acute colonic-pseudo obstruction (OGILVIE syndrome)
spontaneous massive dilation of cecum or right colon; without mechanical obstruction
Who usually develops OGILVIE syndrome?
significantly ill patients (ICU)
How do you diagnose OGILVIE syndrome?
x-ray or CT demonstrate colonic dilation confined to the cecum and proximal colon; the upper limit of normal for cecal size is 9mm;
what is associated with an increased risk of colonic perforation in OGILVIE syndrome?
a cecal diameter greater than 10-12 cm is associated with an increased risk of colonic perforation
How should you manage OGILVIE syndrome?
cecal size should be assessed by abdominal radiographs every 12 hours; conservative is the appropriate first step for mild cases; a nasogastric tube and rectal tube should be placed; all drugs that reduce intestinal motility should be discontinued; NO ORAL LAXATIVES
How do you treat OGILVIE patients who are not improving?
patients with a cecal dilation greater than 12 cm: neostigmine, colonoscopic decompression, surgery
Where’s meckel’s diverticulitis located?
on the anti-mesenteric border of the ileum
what is meckel’s diverticulitis?
remnant of the vitelline duct
how does meckel’s diverticulum present?
RLQ pain
what 3 things mimic appendicitis?
crohn disease, peptic ulcer disease (gastric tissue) and meckel’s diverticulitis
How do you diagnose meckel’s diverticulitis?
angiography: seeing vitelline artery aupplying the diverticulum; Meckel’s scan:Technetium-99m scan- nuclear medicine
how do you treat meckel’s diverticulitis?
surgical resection, PPIs, and NGT for obstructions
what are the complications associated with meckel’s diverticulitis?
intestinal obstruction (intussusception or volvulus), SBO, perforation, or diverticular inflammation
Where does diverticulitis typically present?
LLQ
how do you diagnose diverticulitis?
CT with contrast
what is contraindicated in a patient with diverticulitis?
endoscopy (sigmoidscopy or colonoscopy) or barium enema bc risk of perforation
how should you treat someone with diverticulitis?
empiric therapy: Inpatient: IV fluids, NPO, antibiotics for 7-10 days; outpatients: abx, clear liquid diet–> low residue diet
what are the complications associated with diverticulitis?
abscess, perforation, fistula, liver abscess, stricture
what is an acute mesenteric ischemia?
inadequate blood flow through the mesenteric vessels–> ischemia and gangrene of the bowel wall (superior mesenteric artery); life threatening
how does acute mesenteric ischmia present?
periumbilical pain out of proportion “gut attack”
how do you diagnose an acute mesenteric ischemia?
abdominal plain x-ray shows bowel distention, air-fluid levels, thumbprinting (submucosal edema); CT angiography of abd and pelvis with IV contrast is test of choice
what causes chronic mesenteric ischemia?
long standing atherosclerotic disease; gradual reduction in flow to the intestines
how does chronic mesenteric ischemia present?
abdominal angina- dull crampy periumbilical pain 15-30 minutes after a meal and lasting several hours; patients will have food fear; weight loss
how do you treat chronic mesenteric ischemia?
possible bypass graft surgery
what are three causes of adhesions?
multiple abdominal surgeries, diverticulitis, and crohn disease
what is the microbiology associated with peritonitis?
mixed flora in which gram-negative bacilli and anaerobes predominate
what antibiotics should be given to someone with secondary peitonitis?
fluroquinolone or third-generation cephalosporin plus metronidazole
toxic megacolon is a complication of what two diseases?
IBD: UC; and C. diff
how does toxic megacolon present?
vital sign changes: tachycardia, tachypnea, fever, hypotension; abdominal pain and distention
how do you diagnose toxic megacolon?
clinical; abdominal x-ray or CT with contrast; ENDOSCOPY (sigmoidscopy or colonoscopy) or barium enema is contraindicated bc of risk of perforation
how do you treat toxic megacolon?
IVF, antibiotics, stop narcotics/anticholinergics/antidiarrheals, colonic decompression
where might a volvulus occur?
sigmoid: pregnancy or older patients (due to constipation)
cecum: young adults
how do you diagnose a volvulus?
abdominal plain x-ray shows: bent coffee bean sign”
barium enema shows: “bird’s beak” shape
