Master Gastroenterology
for PLAB 1

What the PLAB 1 Tests in Gastroenterology

PLAB 1 Gastroenterology tests your ability to manage common presentations: dysphagia, dyspepsia, altered bowel habit, rectal bleeding, jaundice, and abdominal pain. You must know diagnostic criteria (e.g., Rome IV for IBS, modified Marsh for coeliac), first-line investigations (e.g., OGD for dysphagia, faecal calprotectin for IBD), and guideline-driven management (e.g., NICE for GORD, BSG for varices). Expect clinical vignettes requiring triage decisions (urgent referral for alarm symptoms), interpretation of liver function tests, and recognition of surgical emergencies (e.g., acute cholecystitis, appendicitis). Drug safety is key: avoid NSAIDs in IBD, use PPI with dual antiplatelet therapy. You must differentiate between upper and lower GI bleeding and apply the Rockall or Blatchford score for risk stratification.

High-Yield Concepts

• Alarm symptoms for upper GI cancer: Dysphagia, weight loss >5% in 6 months, persistent vomiting, epigastric mass, iron deficiency anaemia in men >55 or women >65. Require urgent OGD within 2 weeks per NICE NG12.
• Coeliac disease diagnosis: Serology: IgA tTG (or IgG DGP if IgA deficient). Confirm with duodenal biopsy showing Marsh 3 (villous atrophy). Lifelong gluten-free diet. Screen for osteoporosis and check folate/B12/iron.
• Irritable bowel syndrome (IBS) Rome IV criteria: Recurrent abdominal pain at least 1 day/week for 3 months, associated with ≥2 of: defecation, change in stool frequency, or change in stool form. First-line: low FODMAP diet, loperamide for diarrhoea, linaclotide for constipation if laxatives fail.
• Acute upper GI bleeding management: Resuscitate (IV fluids, blood if Hb <70 g/L). Use Rockall score (age, shock, comorbidities) or Blatchford (urea, Hb, BP, pulse, melaena, syncope, liver disease). Urgent OGD within 24 hours. IV PPI (e.g., omeprazole 80 mg bolus then 8 mg/h) if high-risk stigmata.
• H. pylori testing and treatment: Test with 13C-urea breath test or stool antigen (off PPI for 2 weeks). First-line: triple therapy (omeprazole 20 mg BD, amoxicillin 1 g BD, clarithromycin 500 mg BD for 7 days). If penicillin allergic: metronidazole instead of amoxicillin. Confirm eradication.
• Inflammatory bowel disease: differentiating UC and Crohn's: UC: continuous mucosal inflammation from rectum, crypt abscesses, bloody diarrhoea. Crohn's: skip lesions, transmural inflammation, fistulae, granulomas. First-line for mild-moderate UC: mesalazine. For Crohn's: budesonide or prednisolone. Anti-TNF (infliximab) for refractory.
• Acute pancreatitis: severity and management: Diagnose with amylase >3x upper limit or lipase. Use Glasgow score (≥3 severe): age >55, WBC >15, glucose >10, urea >16, PaO2 <60, Ca <2.0, albumin <32, LDH >600. Management: aggressive IV fluids (Hartmann's 5-10 mL/kg/h), analgesia, CT if not improving at 48h. Avoid ERCP unless cholangitis.
• Variceal bleeding: acute management: Resuscitate, give IV terlipressin (2 mg QDS) and prophylactic antibiotics (ceftriaxone 1 g IV). OGD within 12 hours for band ligation. If uncontrolled, balloon tamponade (Sengstaken-Blakemore) as bridge. TIPS for refractory cases.

Common Traps in Gastroenterology Questions

• Prescribing high-dose NSAIDs for pain in a patient with known IBD or peptic ulcer disease without PPI cover.
• Assuming a normal faecal calprotectin excludes IBD in a patient with chronic diarrhoea — it can be normal in Crohn's with isolated small bowel disease.
• Forgetting to check for coeliac disease before referring a patient with IBS-like symptoms — serology is cheap and non-invasive.
• Using the Glasgow-Blatchford score to decide on the need for OGD in upper GI bleed — it is for pre-endoscopy risk stratification, not to avoid endoscopy.
• Administering IV fluids too aggressively in acute pancreatitis without monitoring for fluid overload or abdominal compartment syndrome.
• Starting PPI therapy before H. pylori testing in a patient with dyspepsia — this can cause false-negative breath test results.

How to Revise Gastroenterology for the PLAB 1

Prioritise memorising the key scoring systems (Rockall, Blatchford, Glasgow for pancreatitis, Child-Pugh for cirrhosis) and the NICE red-flag referral criteria for GI cancers. Questions often present a patient with abdominal pain or altered bowel habit and ask for the next best investigation or management step. Focus on distinguishing surgical from medical causes (e.g., acute abdomen vs. functional disorder). Practise interpreting LFT patterns (hepatocellular vs. cholestatic) and knowing when to request ultrasound vs. CT vs. OGD. Drug interactions are common: avoid metronidazole with warfarin, and remember that PPIs reduce clopidogrel efficacy. Revise the BSG guidelines for dyspepsia and the NICE guidelines for IBD and IBS. Expect at least one question on coeliac disease serology and one on variceal bleeding protocol.

Practise it: MedLumen has 50 Gastroenterology questions for the PLAB 1, each with a full explanation and references.