4.1 Gastrointestinal Disorders, Acute Abdomen, & Liver/Biliary Disease

4.1 Gastrointestinal Disorders, Acute Abdomen, & Liver/Biliary Disease

Upper and Lower Gastrointestinal Bleeding (CAG Guidelines)

Acute gastrointestinal (GI) bleeding represents a major medical emergency requiring rapid risk stratification, resuscitation, and targeted intervention. The Canadian Association of Gastroenterology (CAG) provides clear, evidence-based recommendations for managing both non-variceal and variceal upper GI bleeding (UGIB) as well as lower GI bleeding (LGIB).

Resuscitation & Hemodynamic Stabilization

• Airway & Breathing: Protect airway in patients with massive hematemesis or altered sensorium.
• Vascular Access: Establish two large-bore peripheral IV catheters (16-gauge or 14-gauge) or central access.
• Fluid Resuscitation: Infuse crystalloids (Normal Saline or Ringer's lactate) to restore intravascular volume.
• Restrictive Transfusion Strategy: CAG guidelines recommend a restrictive red blood cell (RBC) transfusion threshold of Hemoglobin (Hb) < 70 g/L for most hemodynamically stable patients, targeting a post-transfusion Hb of 70–90 g/L. In patients with underlying cardiovascular disease or acute coronary syndromes, a higher transfusion threshold of Hb < 80 g/L is recommended.

Risk Stratification

• Glasgow-Blatchford Score (GBS): Performed prior to endoscopy using clinical and laboratory parameters (BUN, Hb, systolic BP, pulse, melena, syncope, hepatic disease, heart failure). A GBS of 0 to 1 identifies low-risk patients who can be safely discharged for outpatient endoscopic evaluation.
• Rockall Score: Incorporates post-endoscopic findings to predict rebleeding risk and mortality.

Non-Variceal Upper GI Bleed (NVUGIB)

• Pharmacotherapy: Administer high-dose IV proton pump inhibitor (PPI) therapy (pantoprazole 80 mg IV bolus followed by 8 mg/h continuous infusion, or 40 mg IV BID) to stabilize blood clots over ulcer beds.
• Endoscopy Timing: Perform upper endoscopy within 24 hours of presentation.
• Endoscopic Management: High-risk stigmata (active spurting, non-bleeding visible vessel, adherent clot) require dual endoscopic therapy (e.g., epinephrine injection combined with thermal coagulation or mechanical clipping).

Variceal Upper GI Bleed (VUGIB)

Cirrhotic patients presenting with hematemesis or melena must be treated for suspected variceal hemorrhage immediately:

1. Vasoactive Therapy: Initiate IV Octreotide (50 µg IV bolus followed by 50 µg/h continuous infusion for 2–5 days) immediately upon presentation to reduce portal venous pressure.
2. Antibiotic Prophylaxis: Administer Ceftriaxone 1 g IV daily for 7 days. Antibiotic prophylaxis significantly reduces bacterial translocation, rebleeding rates, and overall mortality.
3. Urgent Endoscopy: Perform endoscopy within 12 hours of presentation. Endoscopic Variceal Ligation (EVL) is first-line for esophageal varices.
4. Refractory Bleeding: Transjugular Intrahepatic Portosystemic Shunt (TIPS) is indicated for uncontrolled rebleeding.

Lower Gastrointestinal Bleeding (LGIB)

Defined as bleeding distal to the ligament of Treitz, presenting as hematochezia or bright red blood per rectum. Common causes include diverticulosis, angiodysplasia, ischemic colitis, hemorrhoids, and colorectal malignancy.

• Stable Patients: Colonoscopy after oral purge preparation.
• Unstable / Massive Bleeding: CT Angiography (CTA) of the abdomen/pelvis to localize active extravasation (>0.5 mL/min), followed by transcatheter angiographic embolization or emergency segmental colectomy.

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Acute Abdomen & Inflammatory GI Conditions

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Acute Pancreatitis

Diagnostic Criteria (Atlanta Classification)

Diagnosis requires at least 2 of the following 3 criteria:

1. Severe epigastric pain radiating to the back.
2. Serum lipase or amylase elevated > 3 times the upper limit of normal (ULN). Lipase is more specific and remains elevated longer than amylase.
3. Characteristic imaging findings on CT, MRI, or transabdominal ultrasound.

Etiology Mnemonic: I GET STARTED

• I: Idiopathic
• G: Gallstones (40% - most common cause in Canada)
• E: Ethanol / Alcohol (30%)
• T: Trauma
• S: Steroids
• A: Autoimmune
• R: Scorpion stings
• T: Hypertriglyceridemia (serum triglycerides > 11.3 mmol/L)
• E: ERCP
• D: Drugs (azathioprine, valproic acid, thiazides, furosemide)

Acute Management Principles

• Aggressive Crystalloid Resuscitation: Infuse Ringer's lactate at 250–500 mL/h during the first 12–24 hours, targeting a urine output > 0.5 mL/kg/h and reduction in BUN/hematocrit.
• Enteral Nutrition: Early oral feeding or enteral tube feeding (nasogastric or nasojejunal) within 24–72 hours reduces septic complications compared to total parenteral nutrition (TPN).
• Antibiotic Stewardship: Routine prophylactic antibiotics are NOT recommended for sterile pancreatic necrosis. Antibiotics (e.g., Meropenem or Ciprofloxacin + Metronidazole) are indicated only for confirmed infected pancreatic necrosis (CT fine-needle aspiration showing bacteria or gas on CT).

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Liver Function Test Patterns & Jaundice

Hepatocellular vs Cholestatic Patterns

• Hepatocellular Injury: Predominant elevation of ALT and AST (> 5–10x ULN) relative to ALP.
  • AST:ALT ratio > 2:1: Strongly suggests Alcoholic Liver Disease (AST < 500 IU/L).
  • AST & ALT > 1000 IU/L: Indicates acute severe hepatic necrosis secondary to Ischemic Hepatitis ("shock liver"), Acetaminophen Toxicity, or Acute Viral Hepatitis.
• Cholestatic Injury: Predominant elevation of ALP and GGT (> 3x ULN) relative to ALT/AST. Serum GGT elevation confirms hepatic origin of elevated ALP (distinguishing it from bone turnover).

Hyperbilirubinemia Classification

• Unconjugated (Indirect) Hyperbilirubinemia (>85% indirect): Increased heme catabolism (hemolysis, hematoma clearance) or defective conjugation (Gilbert Syndrome - benign mutation in UGT1A1 triggered by fasting, stress, or intercurrent illness).
• Conjugated (Direct) Hyperbilirubinemia (>50% direct): Impaired biliary excretion. Divided into intrahepatic causes (viral hepatitis, alcoholic liver disease, Primary Biliary Cholangitis [PBC - anti-mitochondrial antibody positive]) and extrahepatic obstruction (choledocholithiasis, pancreatic adenocarcinoma, cholangiocarcinoma).

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Biliary Tract Disease

• Biliary Colic: Postprandial episodic RUQ pain (<6 hours) radiating to right scapula due to cystic duct impaction during gallbladder contraction. LFTs and WBC are normal. Ultrasound shows gallstones without wall thickening. Management: Elective laparoscopic cholecystectomy.
• Acute Cholecystitis: Persistent RUQ pain (>6 hours), fever, leukocytosis, positive Murphy's sign. Ultrasound demonstrates gallbladder wall thickening (>4 mm), pericholecystic fluid, and sonographic Murphy's sign. Management: IV fluids, broad-spectrum IV antibiotics (Ceftriaxone + Metronidazole), and early laparoscopic cholecystectomy within 72 hours.
• Choledocholithiasis: Gallstone within the common bile duct (CBD). Cholestatic LFT pattern (elevated ALP, GGT, direct bilirubin) and dilated CBD (>6 mm) on ultrasound. Management: ERCP with sphincterotomy and stone extraction, followed by elective laparoscopic cholecystectomy.
• Acute Cholangitis: Life-threatening infection of obstructed biliary tree.
  • Charcot's Triad: Fever + Jaundice + RUQ Pain.
  • Reynolds' Pentad: Charcot's Triad + Septic Shock + Altered Mental Status.
  • Emergency Management: Resuscitation, broad-spectrum IV antibiotics (Piperacillin-tazobactam), and urgent biliary decompression via ERCP.

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Inflammatory Bowel Disease (IBD)

[!IMPORTANT] MCCQE1 Exam Trap: Timing of CT Imaging in Acute Pancreatitis Do NOT routinely order contrast-enhanced CT of the abdomen in patients presenting with typical acute pancreatitis within the first 48–72 hours of symptom onset. Early CT often underestimates the extent of pancreatic necrosis. CT imaging at presentation is reserved ONLY for diagnostic uncertainty or failure to improve after 48–72 hours of aggressive fluid resuscitation.