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G16 Gastroenterology
Small and Large Bowel Toronto Notes 2019
■ indications for antimicrobial agents in acute diarrhea ◆ septicemia
◆ prolonged fever with fecal blood or leukocytes
◆ clearly indicated: Shigella, V. cholerae, C. difficile, traveller’s diarrhea (enterotoxigenic E. coli
[ETEC]), Giardia, Entamoeba histolytica, Cyclospora
◆ situational: Salmonella, Campylobacter, Yersinia, non-enterotoxigenic E. coli
◆ Salmonella: always treat Salmonella typhi (typhoid or enteric fever); treat other Salmonella
only if there is underlying immunodeficiency, hemolytic anemia, extremes of age, aneurysms, prosthetic valve grafts/joints, sickle cell disease
Traveller’s Diarrhea
• seeInfectiousDiseases,ID13 Chronic Diarrhea
Definition
• passageoffrequentunformedstoolfor>4wk(persistentdiarrheaas14-30d)
• approachissimilartothatofacutediarrheaexceptthatthemajorityofcasesarenon-infectious
Etiology/Classification
• seeDifferentialDiagnosisofCommonPresentingComplaints,G4
Investigations
• guidedbyhistory
• stoolanalysisfor:C.difficiletoxin,C&S,O&P±fecalfat,WBC
• bloodfor:CBC,electrolytes,CRP,TSH,celiacserology(IgAanti-tTG;askforserumprotein
electrophoresis or immunoglobulin quantitation to rule out IgA deficiency which has an increased
frequency in celiac disease)
• colonoscopyandileoscopywithbiopsy
• upperGIendoscopywithduodenalbiopsy
• wirelesssmallbowelendoscopycapsule(lowyield) • trialoflactosefreediet
■ caveat: may delay diagnosis of IBD and celiac disease
Maldigestion and Malabsorption
Definition
• maldigestion:inabilitytobreakdownlargemoleculesinthelumenoftheintestineintotheir component small molecules
• malabsorption:inabilitytotransportmoleculesacrosstheintestinalmucosaintocirculation
Etiology
• maldigestion
■ inadequate mixing of food with enzymes (e.g. post-gastrectomy)
■ pancreatic exocrine deficiency
■ primary diseases of the pancreas (e.g. cystic fibrosis [remember CF can result in pancreatic exocrine
insufficiency as well], pancreatitis, cancer) ■ bile salt deficiency
◆ terminal ileal disease (impaired recycling in view of loss greater than synthesis), bacterial overgrowth (deconjugation of bile salts), rarely liver disease (cholestatic, e.g. primary biliary cirrhosis)
■ specific enzyme deficiencies (e.g. lactase) • malabsorption
■ inadequate absorptive surface
◆ infections/infestations (e.g. Whipple’s disease, Giardia)
◆ immunologic or allergic injury (e.g. celiac disease)
◆ infiltration (e.g. lymphoma, amyloidosis)
◆ fibrosis (e.g. systemic sclerosis, radiation enteritis): fibrosis can lead to loss of surface area but
also areas of stasis with small bowel overgrowth
◆ small bowel resection (length, site, location, presence/absence of ileocecal valve and integrity of
colon are important)
◆ inflammatory: extensive ileal Crohn’s disease (pivotal number is 100 cm as <100 cm = bile salt or
choleretic diarrhea, >100 cm = fatty diarrhea or steatorrhea) ■ drug-induced
◆ cholestyramine, ethanol, neomycin, tetracycline, and other antibiotics ■ endocrine
S. typhi has a rose spot rash (transient maculopapular rash on anterior thorax, upper abdomen), and a prodrome of high fever, bradycardia, headache, and abdominal pain. Diarrhea is not the initial presentation
◆ DM (complex pathogenesis)