347.1 🎓 醫學生版

347.1.0.1 📌 一頁重點

347.1.0.1.1 Abdominal Pain

347.1.1 Visceral vs Parietal vs Referred

Visceral: - Poorly localized, midline - Dull, achy - Crampy - Mediated by autonomic afferents - Examples: bowel distension, ischemia, inflammation of viscera

Parietal (Somatic): - Sharp, localized - Worse with movement - Tender on palpation - Mediated by somatic afferents - Examples: peritonitis, appendicitis with peritoneal irritation

Referred: - Pain felt distant from source - Shared embryologic origin - Examples: diaphragm irritation → shoulder; biliary → right scapula

347.1.2 Pain Quality

Burning: GERD, PUD
Crampy/colicky: bowel obstruction, biliary colic, renal colic
Sharp/lancinating: ureteral colic, pleurisy
Dull/aching: organomegaly, malignancy
Tearing: aortic dissection (back pain)

347.1.3 Acute Abdominal Pain Differential

Surgical: appendicitis, cholecystitis, perforation, obstruction, mesenteric ischemia, ectopic pregnancy
Medical: pancreatitis, gastroenteritis, MI (inferior), DKA, UTI, ureteral colic, IBD flare, ovarian torsion
Acute vs chronic differential important
Always consider pregnancy in reproductive-age females

347.1.4 Chronic Abdominal Pain Differential

IBS
Functional dyspepsia
IBD
Chronic pancreatitis
Endometriosis
Adhesions
Functional somatic syndromes

347.1.4.0.1 Nausea and Vomiting

347.1.5 Causes

GI: gastritis, PUD, gastroenteritis, GI obstruction, motility disorders
CNS: ↑ ICP, migraine, vestibular, anxiety, vomiting center
Metabolic: pregnancy, DM, uremia, electrolyte
Medications/Toxins: chemotherapy, opioids, antibiotics, alcohol
Endocrine: pregnancy (HG), Addison
Functional: cyclic vomiting syndrome, cannabinoid hyperemesis

347.1.6 Pathophysiology

CTZ (chemoreceptor trigger zone) — area postrema
Vomiting center in medulla
Vagal afferents from GI
Vestibular pathway

347.1.7 Management

Treat underlying
Antiemetics:
- 5-HT3 antagonists (ondansetron) — chemotherapy, post-op
- Dopamine antagonists (metoclopramide, prochlorperazine) — many causes
- Antihistamines (meclizine) — vestibular
- Steroids (chemotherapy adjunct)
- Aprepitant (NK1) — chemotherapy

347.1.7.0.1 Dysphagia

347.1.8 Oropharyngeal Dysphagia

Difficulty initiating swallow
Causes: stroke, MS, ALS, myasthenia, Zenker diverticulum, cricopharyngeal dysfunction, tumors

347.1.9 Esophageal Dysphagia

Food sticking
Causes:
- Structural: rings (Schatzki, Plummer-Vinson), webs, strictures, malignancy, eosinophilic esophagitis
- Motility: achalasia, diffuse esophageal spasm, scleroderma

347.1.10 Diagnosis

Modified barium swallow (oropharyngeal)
Barium esophagram (structural)
EGD (gold standard for esophageal)
Esophageal manometry (motility)

347.1.11 Treatment

Per underlying cause

347.1.11.0.1 Dyspepsia

347.1.12 Functional Dyspepsia (Rome IV)

12 weeks duration in 6 months
1+ of: postprandial fullness, early satiety, epigastric pain or burning
No identifiable cause
2 subtypes: postprandial distress syndrome, epigastric pain syndrome

347.1.13 Workup

H. pylori testing
PPI trial
EGD if alarm features (≥ 60 yo, weight loss, dysphagia, bleeding, vomiting, family hx)

347.1.14 Treatment

PPI
H. pylori eradication
Prokinetics (metoclopramide, motilin agonists)
Antidepressants for functional
See Ch349

347.1.14.0.1 Diarrhea

347.1.15 Acute (< 14 days)

Infectious (most common):
- Viral (norovirus, rotavirus)
- Bacterial (Salmonella, Campylobacter, E. coli, C. diff)
- Parasitic (Giardia, Cryptosporidium)
Food-borne, traveler’s diarrhea
Drug-induced (antibiotics, etc.)

347.1.16 Chronic (> 14 days, often > 4 weeks)

Secretory: laxative abuse, hormonal (carcinoid, VIPoma), bile acid malabsorption
Osmotic: lactose intolerance, sorbitol, magnesium-containing
Inflammatory: IBD, microscopic colitis, infections
Malabsorptive: celiac, pancreatic insufficiency, bacterial overgrowth
Motility: hyperthyroidism, diabetic enteropathy

347.1.17 Diagnosis

Stool studies (culture, ova/parasites, calprotectin)
C. diff toxin
Fecal fat
Fecal elastase
Colonoscopy + biopsy
Imaging if structural

347.1.18 Treatment

Hydration (critical)
Loperamide (if no infection)
Specific therapy per cause

347.1.18.0.1 GI Bleeding

347.1.19 Upper GI Bleeding (UGIB)

Above ligament of Treitz (duodenum)
Hematemesis (vomiting blood)
Melena (black, tarry stool — > 50 mL blood)
Coffee-ground emesis
Causes: PUD (most), variceal, Mallory-Weiss, esophagitis, malignancy, vascular (Dieulafoy), aortoenteric fistula
Workup: EGD; ICU if unstable; PPI infusion; somatostatin for variceal; balloon tamponade

347.1.20 Lower GI Bleeding (LGIB)

Below ligament of Treitz
Hematochezia (bright red blood) — distal
Sometimes melena (if proximal)
Causes: diverticulosis, AVM, hemorrhoids, IBD, ischemic colitis, malignancy, infection
Workup: colonoscopy; CT angiography for massive

347.1.21 Obscure GI Bleeding

Bleeding from middle small bowel
Workup: video capsule endoscopy, double-balloon enteroscopy, push enteroscopy

347.1.21.0.1 Constipation

347.1.22 Causes

Functional (most)
Diet (low fiber, low fluid)
Medications (opioids, anticholinergics, CCBs, Ca, Fe)
Endocrine (hypothyroid, DM, hyperCa)
Neurogenic (Parkinson, spinal cord)
Mechanical (obstruction, megacolon)

347.1.23 Workup

History (Rome IV criteria for functional)
Imaging if obstruction suspected
Colonoscopy if alarm features
Anorectal manometry for outlet

347.1.24 Treatment

Lifestyle (fiber, fluid, exercise)
Osmotic laxatives (polyethylene glycol, lactulose)
Stimulant laxatives (senna, bisacodyl)
Stool softeners
Prokinetics (prucalopride)
Lubiprostone, linaclotide for IBS-C/CIC

347.1.24.0.1 Weight Loss + Anorexia

347.1.25 Workup

Detailed history
Lab: CBC, BMP, LFT, TSH, glucose, HIV, hepatitis, etc.
Imaging if symptoms
Cancer screening per age
Mental health screening

347.1.26.0.1 Jaundice

347.1.27 Categories

Pre-hepatic: hemolysis (unconjugated bilirubin ↑)
Hepatic: hepatocellular (mixed bilirubin), Gilbert (unconjugated ↑ in stress)
Post-hepatic (cholestatic): extrahepatic obstruction (stones, malignancy), intrahepatic cholestasis (drugs, PSC, PBC); conjugated bilirubin ↑

347.1.28 Workup

LFT (AST, ALT, ALP, GGT, bilirubin total + direct)
Hemolysis workup
US abdomen (rule out obstruction)
MRCP, ERCP if obstruction
Viral hepatitis, autoimmune workup

347.1.28.0.1 Diagnostic Tools Overview

347.1.29 Endoscopy

EGD (upper): esophagus, stomach, duodenum
Colonoscopy: colon + terminal ileum
Sigmoidoscopy: distal
Capsule endoscopy: small bowel
Single/double-balloon enteroscopy: deep small bowel
ERCP: biliary
EUS: pancreaticobiliary, submucosal

347.1.30 Imaging

US abdomen (gallstones, ascites, masses, fatty liver)
CT (acute abdomen, mass)
MRI / MRCP (biliary, liver)
CT angiography (bleeding, mesenteric ischemia)
HIDA scan (cholecystitis, biliary leak)

347.1.31 Lab

LFT, lipase / amylase, fecal calprotectin, anti-tTG (celiac), ANA, ANCA, etc.
H. pylori testing (urea breath, stool antigen)
Fecal elastase (pancreatic insufficiency)
Stool culture, parasitic studies, calprotectin

347.1.32 Specialized

Manometry (esophageal, anorectal)
pH monitoring (GERD)
Breath tests (H. pylori, lactose intolerance, SIBO)
Liver elastography (FibroScan)

347.1.32.1 🩺 床邊速查

Abdominal pain: visceral (poorly localized) vs parietal (sharp localized) vs referred
Dysphagia: oropharyngeal vs esophageal; modified barium / EGD / manometry
Acute diarrhea < 14 d: infectious (viral most common); stool studies + culture
GI bleed UGIB: PUD, varices; EGD + PPI + somatostatin if variceal
LGIB: diverticulosis, AVM; colonoscopy + CT angio
Jaundice: pre-hepatic (hemolysis) vs hepatic vs post-hepatic; LFT + US first
Weight loss workup: malignancy + endocrine + infection + GI + mental health
Functional GI (IBS, dyspepsia): Rome IV criteria