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G4 Gastroenterology
Differential Diagnosis of Common Complaints Toronto Notes 2019
Visualizing the GI Tract
• seeMedicalImaging,MI16
Esophagus, Stomach, Duodenum
• OGD:bestvisualizationofmucosa;alsoallowsfortherapeuticintervention(e.g.bandingvarices, thermal therapy/clipping/injecting bleeding ulcers, and dilatation e.g. treatment of esophageal strictures)
■ consider barium swallow first if dysphagia, decreased level of consciousness (increases risk of aspiration), inability to cooperate (increases risk of pharyngeal trauma during intubation), possibility of fistulas
■ endotracheal intubation first if massive upper GI bleed, acidemia, or inability to protect airway
Small Bowel
• mostdifficulttovisualize,especiallyifmucosaldetailisneeded
• CTenterographymoreaccuratethansmallbowelfollowthrough,butbothhavelowsensitivity
• MRIsmallbowelimagingincreasinglyavailable,especiallyusefulifradiationexposureisanissue(e.g.
young patient, multiple radiological images already done)
■ note: MRI enteroclysis: luminal contrast administered by nasojejunal tube to dilate the small bowel
– disliked by both radiologist and patient, but may improve sensitivity
• “doubleballoon”enteroscopy(enteroscopewithproximalanddistalballoonstopropelendoscope
into jejunum from mouth or into jejunum/ileum or into ileum from anus) may be most sensitive but
currently available only in selected centres; technically demanding
• wirelessendoscopycapsule(26x11mmcapsuleisswallowed,transmitsimagestoacomputer;
contraindicated in bowel obstruction) is also accurate in diagnosis but unable to provide any therapeutic intervention
Colon and Terminal Ileum
• colonoscopy,withbiopsyifrequired;contraindicatedinperforation,acutediverticulitis,andsevere colitis (increased risk of perforation)
• CTcolonography(“virtualcolonoscopy”)moreaccurateindiagnosingdiverticulosis,extrinsicpressure on colon (e.g. ovarian cancer compressing sigmoid colon), and fistulae; increasing evidence for use in colorectal cancer screening, especially for assessment of right side of colon in cases where colonoscopy is less sensitive
■ most often used when optical endoscopic colonoscopy is a risk (e.g. frail elderly) or unsuccessful (e.g. stricture)
Pancreatic/Biliary Duct
• MRCPalmostassensitiveasERCPindeterminingifbileductobstructionpresent,butlessaccuratein determining cause of obstruction (tumour, stone, stricture)
• ERCPiftherapeuticinterventionlikelytoberequired:strongsuspicionofstone,obstructionrequiring stenting, or if tissue sampling required
Differential Diagnosis of Common Complaints
Acute Upper Abdominal Pain
Remember to rule out thoracic sources, e.g. myocardial infarction, pneumonia, dissecting aneurysm
Obscure But Treatable Causes of Abdominal Pain
• Acute Intermittent Porphyria
• Hereditary Angioedema
• Familial Mediterranean Fever
• Vasculitis (e.g. polyarteritis nodosa)
Inflammatory Diarrhea: Occurs when there is damage to the mucosal lining or brush border, which leads to a passive loss of protein-rich fluids and a decreased ability to absorb
these lost fluids. Diarrhea may be profuse or very small in volume. Often associated with abdominal pain ± fever and chills Non-Inflammatory Diarrhea: No damage to the mucosal lining. N/V may be present. Fever, chills, blood in the stool, severe abdominal pain or tenderness are not present
• seeGeneralSurgery,GS4
Table 2. Differential Diagnosis of Common Presenting Complaints
CHRONIC/ RECURRENT ABDOMINAL PAIN
ACUTE DIARRHEA
*Causes of bloody diarrhea
Inflammatory
PUD
Biliary colic
IBD
Chronic pancreatitis
Inflammatory
Bacterial
Shigella* Salmonella* Campylobacter* Yersinia*
E. coli (EHEC 0157:H7)*
Neoplastic/ Vascular
Recurrent bowel obstruction Mesenteric ischemia
Sickle cell anemia
Protozoal
E. histolytica* (amoebiasis) Strongyloides
Others
NSAIDs IBD* Ischemic*
Toxin
Lead poisoning
Non-Inflammatory
Bacterial
S. aureus
C. perfringens
B. cereus
E. coli (ETEC, EPEC) Salmonella enteritidis Vibrio cholera Protozoal
Giardia lamblia
Other
Mittleschmertz Endometriosis Porphyria
IBS
Radiculopathy Abdominal wall pain syndrome
Viral
Rotavirus
Norwalk
CMV
Drugs
Antibiotics
Colchicine
Laxatives
Antacids (magnesium)