Master Gastroenterology
for MRCP Part 1

Core Concepts

Gastroenterology encompasses diseases of the digestive tract from esophagus to anus, including associated organs like the liver, pancreas, and biliary system. Key areas include inflammatory bowel disease (IBD - Crohn's, Ulcerative Colitis), irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), celiac disease, acute and chronic liver diseases (viral hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease, autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis), gallstone disease, pancreatitis, and gastrointestinal malignancies. Understanding the interplay of mucosal immunity, gut microbiome, motility, secretion, and absorption is crucial. Common presentations often involve pain, altered bowel habits, bleeding, or malabsorption. Liver disease can manifest with jaundice, ascites, encephalopathy, or coagulopathy. Pancreatic disease typically presents with abdominal pain and can affect endocrine and exocrine function.

Clinical Presentation

• Abdominal Pain: Location and character are key.
  • Epigastric: GERD, PUD, pancreatitis, gallstones.
  • RUQ: Gallstones, hepatitis, liver abscess, cholangitis.
  • RLQ: Appendicitis, Crohn's, mesenteric adenitis.
  • LLQ: Diverticulitis, Ulcerative Colitis.
  • Diffuse: IBS, gastroenteritis, bowel obstruction, peritonitis.
• Dysphagia: Difficulty swallowing (mechanical obstruction vs. motility disorder).
• Odynophagia: Painful swallowing (esophagitis, infection).
• Nausea/Vomiting: Common, consider obstruction, gastroparesis, infection, increased intracranial pressure.
• Diarrhea:
  • Acute: Infective gastroenteritis.
  • Chronic: IBD, IBS, malabsorption (celiac), microscopic colitis, endocrine causes.
  • Bloody: IBD, infective colitis (e.g., C. difficile), diverticular bleeding, malignancy.
  • Steatorrhea: Pancreatic insufficiency, celiac, short bowel syndrome.
• Constipation: IBS, opioid use, hypothyroidism, electrolyte imbalance, mechanical obstruction.
• GI Bleeding:
  • Hematemesis (fresh blood/coffee grounds): Upper GI (ulcer, varices, Mallory-Weiss tear).
  • Melena (black, tarry stools): Upper GI or proximal small bowel.
  • Hematochezia (fresh red blood PR): Lower GI (diverticulosis, haemorrhoids, IBD, malignancy).
• Jaundice: Pre-hepatic (hemolysis), hepatic (hepatitis, cirrhosis), post-hepatic (gallstones, pancreatic mass).
• Ascites: Portal hypertension (cirrhosis), cardiac failure, malignancy, pancreatitis.
• Weight Loss: Malignancy, malabsorption, IBD, hyperthyroidism.

Diagnosis (Gold Standard)

• Endoscopy (OGD, Colonoscopy): Direct visualization and biopsy. Gold standard for GERD complications, PUD, IBD, celiac disease (duodenal biopsy), and screening for colorectal cancer.
• Imaging:
  • Ultrasound Abdomen: Initial for gallstones, liver lesions, ascites.
  • CT Abdomen/Pelvis: Pancreatitis, diverticulitis, appendicitis, staging malignancy, bowel obstruction.
  • MRI Liver/MRCP: Detailed liver characterization, biliary tree imaging (e.g., PSC, choledocholithiasis).
  • Barium Studies: Esophageal motility, strictures (less common now).
• Lab Tests:
  • LFTs: Hepatitis, cholestasis, cirrhosis.
  • Amylase/Lipase: Acute pancreatitis.
  • Serology: H. pylori, Celiac antibodies (anti-TTG, anti-endomysial), autoimmune hepatitis antibodies (ANA, ASMA), viral hepatitis serology.
  • Stool Tests: Fecal calprotectin (IBD activity), C. difficile toxin, O&P (parasites), bacterial cultures.
  • Breath Tests: H. pylori (urea breath test), SIBO (hydrogen breath test).
• Capsule Endoscopy: Small bowel pathology (obscure GI bleeding, Crohn's).
• ERCP/EUS: Therapeutic (ERCP for stone removal, stent placement) and diagnostic (EUS for pancreatic lesions, bile duct assessment).

Management (First Line)

• GERD/PUD: Proton Pump Inhibitors (PPIs) are first-line. H2-receptor antagonists are alternatives. H. pylori eradication therapy (triple therapy) for positive PUD.
• IBD (Crohn's/UC):
  • Induction: Corticosteroids (oral/IV), biologics (e.g., anti-TNF alpha like infliximab, adalimumab), immunomodulators (azathioprine, methotrexate).
  • Maintenance: 5-Aminosalicylates (5-ASAs) for UC, immunomodulators, biologics.
• IBS: Dietary modifications (FODMAP diet), lifestyle changes, laxatives/anti-diarrheals, antispasmodics. Psychological therapies.
• Celiac Disease: Strict gluten-free diet.
• Acute Pancreatitis: Supportive care (IV fluids, analgesia), NPO initially. Treat underlying cause (e.g., ERCP for gallstone pancreatitis).
• Chronic Liver Disease (e.g., Cirrhosis):
  • Alcohol cessation, antivirals for viral hepatitis, ursodeoxycholic acid for PBC.
  • Complication management: Diuretics for ascites, lactulose/rifaximin for encephalopathy, beta-blockers/variceal banding for varices.
  • Liver transplant for decompensated end-stage liver disease.
• Cholelithiasis: Cholecystectomy for symptomatic gallstones. ERCP for choledocholithiasis.
• Diverticulitis: Oral antibiotics for uncomplicated cases, IV antibiotics for complicated. Surgery for recurrent or complicated disease.