Master Gastroenterology
for PLAB 1

Core Concepts

The gastrointestinal (GI) system is responsible for digestion, nutrient absorption, and waste elimination. Core concepts include understanding the anatomy and physiology from mouth to anus, common presenting symptoms, and major disease categories. Key areas of focus for PLAB 1 include inflammatory conditions (GORD, IBD), infectious diseases (gastric, intestinal), obstructive pathologies (strictures, tumours, gallstones), malabsorption syndromes (Coeliac), bleeding (ulcers, varices, diverticular), and malignancies (colorectal, oesophageal, pancreatic).

Clinical Presentation

• Dysphagia/Odynophagia: Difficulty/painful swallowing. Consider GORD, oesophageal stricture, achalasia, oesophageal cancer.
• Abdominal Pain: Character (burning, colicky, constant), location (epigastric, RUQ, RLQ, periumbilical, diffuse), radiation, and associated features (vomiting, fever, altered bowel habit). Differentiate acute vs. chronic.
• Nausea & Vomiting: Common. Assess timing, contents (bile, undigested food, blood), and associated symptoms. Consider gastroenteritis, obstruction, PUD, pancreatitis, cholecystitis.
• Altered Bowel Habits:
  • Diarrhoea: Acute (infectious) vs. Chronic (IBD, IBS, malabsorption). Assess frequency, consistency, presence of blood/mucus/fat.
  • Constipation: Frequency, straining, incomplete evacuation. Consider IBS, obstruction, medications.
• Rectal Bleeding: Haematochezia (fresh blood, e.g., haemorrhoids, diverticulitis, IBD, colorectal cancer) vs. Melaena (dark, tarry stools, upper GI bleed).
• Weight Loss (Unintentional): Alarm symptom. Consider malignancy, IBD, Coeliac disease, hyperthyroidism.
• Jaundice: Yellow discolouration of skin/sclera due to elevated bilirubin. Pre-hepatic (haemolysis), Hepatic (hepatitis, cirrhosis), Post-hepatic (biliary obstruction – gallstones, pancreatic head mass).
• Bloating & Distension: IBS, obstruction, ascites.
• Heartburn/Regurgitation: Burning sensation retrosternally, acid taste in mouth. Classic GORD symptoms.

Diagnosis (Gold Standard)

• Gastro-oesophageal Reflux Disease (GORD): Clinical diagnosis, PPI trial. Endoscopy with biopsy for alarm symptoms or refractory cases.
• Peptic Ulcer Disease (PUD): Oesophago-gastro-duodenoscopy (OGD) with biopsy for H. pylori.
• Inflammatory Bowel Disease (IBD - Crohn's/UC): Colonoscopy with biopsy.
• Coeliac Disease: Serology (anti-TTG IgA, anti-endomysial IgA) followed by duodenal biopsy (while on gluten-containing diet).
• Acute Pancreatitis: Serum lipase or amylase >3x upper limit of normal + CT abdomen for complications/severity.
• Acute Cholecystitis: Abdominal ultrasound.
• Cirrhosis: Liver biopsy (often clinical diagnosis based on imaging, labs, and elastography).
• Hepatitis (Viral): Serology for specific viral markers.
• Colorectal Cancer: Colonoscopy with biopsy.

Management (First Line)

• GORD: Lifestyle modifications (elevate head of bed, avoid triggers), Proton Pump Inhibitors (PPIs).
• PUD: PPIs. If H. pylori positive, triple therapy (PPI + two antibiotics, e.g., clarithromycin, amoxicillin/metronidazole).
• IBD (UC/CD): Aminosalicylates (e.g., mesalazine) for UC. Corticosteroids for flares. Immunomodulators (azathioprine, methotrexate) or biologics (anti-TNF) for maintenance.
• Coeliac Disease: Strict lifelong gluten-free diet.
• Acute Pancreatitis: Aggressive IV fluid resuscitation, analgesia, NPO (nil by mouth).
• Acute Cholecystitis: NPO, IV fluids, antibiotics, laparoscopic cholecystectomy (often within 72 hours).
• Cirrhosis Complications:
  • Ascites: Diuretics (spironolactone + furosemide), sodium restriction.
  • Hepatic Encephalopathy: Lactulose, rifaximin.
  • Variceal Bleeding: Endoscopic band ligation, non-selective beta-blockers (prophylaxis).
• Colorectal Cancer: Surgical resection, chemotherapy, radiotherapy depending on stage.
• Irritable Bowel Syndrome (IBS): Lifestyle and dietary modifications (FODMAP diet), symptomatic treatment (laxatives, antidiarrhoeals, antispasmodics, low-dose TCAs for pain).