Dysphagia and odynophagia
A practical approach to difficulty swallowing and pain on swallowing: telling oropharyngeal from oesophageal causes, red flags, first tests and treatment.
Checked against sourcesVerified 28 October 2026
Gastroenterology
Diseases of the gut, liver, pancreas and biliary system.
Introduction
Gastroenterology covers the gut from the throat to the anus, together with the liver, the gallbladder and bile ducts, and the pancreas. These organs share symptoms (pain, vomiting, diarrhoea, bleeding, jaundice), so a large part of the work is deciding which organ is at fault and how urgent it is.
This section follows the food: the oesophagus and stomach first, then diarrhoea and the small bowel, the surgical emergencies of the abdomen, the colon and inflammatory bowel disease, the gallbladder and bile ducts, the liver (from an abnormal blood test through hepatitis and metabolic disease to cirrhosis and liver cancer), and last the pancreas.
Every topic uses the same layout: a short summary, what you should be able to do afterwards, the mechanism, the clinical picture, tests, treatment and the traps. Cut-offs and drug choices are checked against named guidelines and shown with their source, because guidelines and countries sometimes differ.
How to study gastroenterology
Read the liver topics in the order given. The abnormal liver test and jaundice topic comes first because the pattern of the blood tests (hepatocellular, cholestatic or mixed) sorts most of the later diagnoses, and cirrhosis only makes sense after the diseases that cause it.
For each disease, learn where in the gut or organ the process sits and what that does to the symptoms: pain of obstruction, bleeding from ulcer or varix, jaundice from a blocked duct. Treatments then follow from the cause, and the red flags tell you when the patient needs a senior or a surgeon at once.
Learn the emergencies as pathways: upper gastrointestinal bleeding, acute cholangitis, the acute abdomen with obstruction or ischaemia, spontaneous bacterial peritonitis and acute liver failure. Practise saying the first three actions aloud, and use the check-yourself questions at the end of each topic a few days later.
Gastroenterology links to infectious disease (hepatitis, diarrhoea, C. difficile), haematology and oncology (the gut and liver cancers), endocrinology (neuroendocrine tumours) and surgery, so follow the related links. Content here is for study and does not replace local protocols or a senior clinician's judgement.
Contents by part
The topics below are in teaching order. Each part builds on the one before it.
- Swallowing and the oesophagus. Start at the top of the tube: how swallowing goes wrong, then reflux, motility and the oesophageal masses.
- Stomach and duodenum. Acid, ulcers, infection with Helicobacter pylori and the stomach cancers.
- Diarrhoea, absorption and the small bowel. From the symptom of diarrhoea to infection, malabsorption, functional disease and the small-bowel tumours.
- Approach to diarrhoea
- Infectious diarrhoea and foodborne illness
- Clostridioides difficile infection
- Malabsorption, maldigestion and lactose intolerance
- Coeliac disease
- Carcinoid syndrome and neuroendocrine tumours of the gut
- Irritable bowel syndrome
- Microscopic colitis and short bowel syndrome
- Small bowel tumours and GIST
- Obstruction, ischaemia and the acute abdomen. The surgical gut: blockage, dead bowel and the common causes of an acute abdomen.
- Colon, rectum and inflammatory bowel disease. Bleeding, inflammation, ischaemia and cancer of the lower gut.
- Ulcerative colitis and inflammatory bowel disease overview
- Crohn disease
- Ischaemic colitis
- Gastrointestinal bleeding
- Colorectal cancer
- Pilonidal disease
- Inflammatory bowel disease: drug treatment and surveillance
- Constipation and faecal incontinence
- Colorectal polyps, polyposis and Lynch syndrome
- Anal cancer and anal intraepithelial neoplasia
- Gallbladder and bile ducts. Stones and their complications, then the autoimmune bile-duct diseases.
- Liver: tests, hepatitis and metabolic disease. Start with the abnormal liver test and jaundice, then the viral, autoimmune and inherited liver diseases.
- Abnormal liver function tests and jaundice
- Isolated hyperbilirubinaemia and bilirubin disorders
- Hepatitis overview, acute liver failure, hepatitis A and E
- Hepatitis B and hepatitis D
- Hepatitis C
- Autoimmune hepatitis
- Metabolic dysfunction-associated steatotic liver disease
- Haemochromatosis
- Wilson disease
- Drug-induced liver injury and paracetamol overdose
- Alcohol-related liver disease and alcoholic hepatitis
- Acute liver failure and liver transplantation
- Liver abscess and parasitic liver disease
- Cirrhosis and liver tumours. The end stage of chronic liver disease, its complications and the tumours that arise in it.
- Pancreas. Inflammation, then tumours of the exocrine and endocrine pancreas.
Topics
Infectious oesophagitis
How Candida, herpes simplex and cytomegalovirus inflame the oesophagus, how they are diagnosed, treated and prevented.Checked against sourcesVerified 28 October 2026Achalasia and oesophageal motility disorders
Achalasia and other oesophageal motility disorders: symptoms, manometry, classification and treatment from dilation to POEM.Checked against sourcesVerified 28 October 2026Oesophageal diverticula
Oesophageal pouches: Zenker's, mid-oesophageal traction and epiphrenic diverticula, with causes, symptoms, barium diagnosis and treatment.Checked against sourcesVerified 28 October 2026Gastro-oesophageal reflux disease and Barrett oesophagus
What GERD and Barrett oesophagus are, how they present and are diagnosed, and how they are managed from lifestyle measures and PPIs to surgery.Checked against sourcesVerified 28 October 2026Hiatal hernia
A hernia of stomach through the diaphragmatic hiatus: types, symptoms, Cameron anaemia, imaging, surgery for paraesophageal hernia, and emergencies.Checked against sourcesVerified 28 October 2026
Oesophageal cancer
What oesophageal cancer is, how it presents and is diagnosed and staged, and how it is treated by stage in high- and low-resource settings.Checked against sourcesVerified 28 October 2026Eosinophilic oesophagitis
How eosinophilic inflammation causes dysphagia and food impaction, how biopsy finds EoE, and how PPIs, topical steroids, diet and dupilumab treat it.Checked against sourcesVerified 31 October 2026Mallory-Weiss tear and oesophageal perforation
Superficial retching-induced tears at the cardia versus full-thickness oesophageal rupture: how to tell them apart and treat both.Checked against sourcesVerified 31 October 2026Gastritis and Helicobacter pylori infection
Classification, diagnosis and treatment of H. pylori and non-H. pylori gastritis, with stress ulcer prophylaxis and gastric cancer prevention.Checked against sourcesVerified 28 October 2026Peptic ulcer disease
Peptic ulcer disease: causes, symptoms, endoscopic diagnosis, eradication of H. pylori, and management of bleeding, perforation and obstruction.Checked against sourcesVerified 28 October 2026Zollinger-Ellison syndrome
A gastrin-secreting tumour of the duodenum or pancreas causing acid hypersecretion, refractory ulcers and diarrhoea, often tied to MEN1.Checked against sourcesVerified 28 October 2026Gastric cancer
A common upper GI malignancy with marked geographic variation: how it develops, presents, is staged, and is treated today.Checked against sourcesVerified 28 October 2026Functional dyspepsia and gastroparesis
Functional dyspepsia and gastroparesis: how they overlap, how to tell them apart, and how to manage them.Checked against sourcesVerified 31 October 2026Approach to diarrhoea
How to assess diarrhoea: mechanisms, acute and chronic causes, dehydration, stool tests, treatment and red flags.Checked against sourcesVerified 28 October 2026Infectious diarrhoea and foodborne illness
Infectious diarrhoea and foodborne illness: causes, clinical clues, testing and management.Checked against sourcesVerified 28 October 2026Clostridioides difficile infection
How Clostridioides difficile injures the colon, how it is found, and how current guidelines treat, prevent and guard against recurrence.Checked against sourcesVerified 28 October 2026Malabsorption, maldigestion and lactose intolerance
Malabsorption and maldigestion: from physiology to classified causes, symptoms, investigations and management, with a full section on lactose intolerance.Checked against sourcesVerified 28 October 2026Coeliac disease
Immune-mediated small-bowel disease triggered by gluten in HLA-DQ2 or DQ8 carriers, from definition to diagnosis, diet and complications.Checked against sourcesVerified 28 October 2026Carcinoid syndrome and neuroendocrine tumours of the gut
Gut neuroendocrine tumours: grading, why carcinoid syndrome needs liver metastases, flushing, diarrhoea, heart valves, diagnosis and modern treatment.Checked against sourcesVerified 28 October 2026Irritable bowel syndrome
A common gut-brain axis disorder: symptom-based diagnosis, subtype classification, and step-by-step, safe management.Checked against sourcesVerified 28 October 2026Microscopic colitis and short bowel syndrome
Chronic watery diarrhoea in older adults (microscopic colitis, budesonide) and intestinal failure after major small-bowel resection (short bowel syndrome).Checked against sourcesVerified 31 October 2026Small bowel tumours and GIST
Small bowel tumours—adenocarcinoma, lymphoma, neuroendocrine tumours, metastases—and GIST: presentation, work-up and treatment.Checked against sourcesVerified 31 October 2026Small bowel obstruction
Mechanical blockage of the small intestine: causes, pathophysiology, diagnosis by CT and water-soluble contrast, and when to operate or observe.Checked against sourcesVerified 28 October 2026Ileus and acute colonic pseudo-obstruction
Ileus and Ogilvie syndrome: causes, diagnosis and stepwise management from conservative care to neostigmine, decompression and surgery.Checked against sourcesVerified 28 October 2026Acute mesenteric ischaemia
Sudden loss of intestinal blood flow: causes, presentation, CT angiography, and time-critical revascularisation and bowel resection.Checked against sourcesVerified 28 October 2026Acute appendicitis
A common surgical emergency: how obstruction of the appendix leads to pain, perforation and abscess, and how it is diagnosed and treated.Checked against sourcesVerified 28 October 2026Diverticular disease
Diverticulosis and its complications - bleeding, diverticulitis and SCAD - from pathogenesis to management.Checked against sourcesVerified 28 October 2026Large bowel obstruction and volvulus
How large bowel obstruction and volvulus present, are diagnosed on imaging, and are managed from resuscitation to stenting, diversion and resection.Checked against sourcesVerified 28 October 2026Abdominal wall and groin hernias
Groin and abdominal-wall hernias: types, anatomy of the inguinal and femoral canals, risk factors, examination, complications and evidence-based treatment.Checked against sourcesVerified 28 October 2026Peritonitis and the acute abdomen
How secondary peritonitis develops from a perforated or necrotic hollow viscus, how it is recognised, imaged, resuscitated, and when surgical source control.Checked against sourcesVerified 31 October 2026Appendiceal tumours and pseudomyxoma peritonei
How appendiceal neuroendocrine, mucinous and glandular tumours present, how they are staged, and when right hemicolectomy, cytoreductive surgery and HIPEC.Checked against sourcesVerified 31 October 2026Ulcerative colitis and inflammatory bowel disease overview
Inflammatory bowel disease: how ulcerative colitis presents, is diagnosed, scored, treated, and followed; Crohn disease compared on the features that matter.Checked against sourcesVerified 28 October 2026Crohn disease
Transmural IBD from mouth to anus: episodic pain, diarrhoea, strictures and fistulas, and stepwise then advanced therapy.Checked against sourcesVerified 28 October 2026Ischaemic colitis
Sudden colonic ischemia, usually segmental and left-sided: how it presents, how we confirm and stage it, and when surgery is needed.Checked against sourcesVerified 28 October 2026Gastrointestinal bleeding
How to recognise, assess, investigate and treat bleeding anywhere in the gastrointestinal tract, from first approach to prevention.Checked against sourcesVerified 28 October 2026Colorectal cancer
Colorectal cancer from polyp to metastasis: epidemiology, risk factors, site-specific presentation, staging, surgery, chemotherapy and screening.Checked against sourcesVerified 28 October 2026Pilonidal disease
Acquired disease of hair follicles in the natal cleft, from acute abscess to chronic sinus: differential diagnosis, modern treatment and low-resource care.Checked against sourcesVerified 28 October 2026Inflammatory bowel disease: drug treatment and surveillance
Aminosalicylates, corticosteroids, immunomodulators and biologics in IBD; how to escalate therapy and how to run colonoscopic cancer surveillance.Checked against sourcesVerified 31 October 2026Constipation and faecal incontinence
Causes, warning signs, anorectal physiology, assessment and a practical management ladder for constipation and faecal incontinence in adults.Checked against sourcesVerified 31 October 2026Colorectal polyps, polyposis and Lynch syndrome
Benign mucosal growths and the hereditary syndromes behind them; how they become cancer, how colonoscopy removes them, and when to look again.Checked against sourcesVerified 31 October 2026Anal cancer and anal intraepithelial neoplasia
How HPV-driven anal squamous cell cancer develops, who is at risk, how it is staged and treated with chemoradiotherapy, and how precancerous lesions are.Checked against sourcesVerified 31 October 2026Cholelithiasis and biliary colic
Gallstones: types, risks, biliary colic, complications, ultrasound diagnosis, treatment, and low-resource guidance.Checked against sourcesVerified 28 October 2026Acute cholecystitis
How gallstone obstruction inflames the gallbladder, how we recognise, grade and image it, and how we treat it safely.Checked against sourcesVerified 28 October 2026Choledocholithiasis, acute cholangitis and gallstone ileus
Choledocholithiasis, acute cholangitis and gallstone ileus: presentation, diagnosis, risk stratification, antibiotics, ERCP and urgent biliary drainage.Checked against sourcesVerified 28 October 2026Primary biliary cholangitis
Autoimmune destruction of small intrahepatic bile ducts; raised ALP and AMA in middle-aged women, with UDCA first-line therapy.Checked against sourcesVerified 28 October 2026Primary sclerosing cholangitis
Chronic cholestatic disease: inflammation and fibrosis of intra- and extrahepatic bile ducts, IBD link, beaded MRCP, no proven drug, transplant definitive.Checked against sourcesVerified 28 October 2026Gallbladder cancer and cholangiocarcinoma
How biliary tract cancers arise, how they are classified, how gallbladder cancer and cholangiocarcinoma are found, and how they are treated.Checked against sourcesVerified 31 October 2026Abnormal liver function tests and jaundice
How to read liver blood tests: injury versus cholestasis versus synthetic failure, jaundice patterns, and stepwise algorithms for investigation.Checked against sourcesVerified 28 October 2026Isolated hyperbilirubinaemia and bilirubin disorders
Inherited disorders with isolated bilirubin rises: bilirubin metabolism, Gilbert, Crigler-Najjar, Dubin-Johnson and Rotor syndromes, neonatal jaundice.Checked against sourcesVerified 28 October 2026Hepatitis overview, acute liver failure, hepatitis A and E
Acute and chronic hepatitis: causes, phases, the five hepatotropic viruses, acute liver failure recognition and ICU care, and hepatitis A and E management.Checked against sourcesVerified 28 October 2026Hepatitis B and hepatitis D
Chronic hepatitis B and D: virology, serology, natural history, treatment with tenofovir or entecavir, prevention, and severe HDV co-infection.Checked against sourcesVerified 28 October 2026Hepatitis C
What hepatitis C is: transmission, natural history, screening, diagnosis, curative direct-acting antiviral therapy, follow-up and prevention.Checked against sourcesVerified 28 October 2026Autoimmune hepatitis
Autoimmune hepatitis: who it affects, how it is diagnosed, and how immunosuppression controls it long term.Checked against sourcesVerified 28 October 2026Metabolic dysfunction-associated steatotic liver disease
What MASLD is, how it progresses to cirrhosis and cancer, how to assess fibrosis, and how to manage it in adults.Checked against sourcesVerified 28 October 2026Haemochromatosis
Iron overload disorders: HFE and non-HFE haemochromatosis, secondary iron overload, symptoms, tests, phlebotomy and complications.Checked against sourcesVerified 28 October 2026Wilson disease
Rare autosomal recessive copper overload of liver, brain, cornea and kidney: copper studies, Leipzig score, lifelong chelator or zinc treatment.Checked against sourcesVerified 28 October 2026Drug-induced liver injury and paracetamol overdose
Causes, patterns, diagnosis, causality and treatment of drug-induced liver injury, with the paracetamol nomogram and acetylcysteine.Checked against sourcesVerified 31 October 2026Alcohol-related liver disease and alcoholic hepatitis
Whole spectrum from steatosis to cirrhosis, with diagnosis, severity scores, steroid treatment and withdrawal care for alcoholic hepatitis.Checked against sourcesVerified 31 October 2026Acute liver failure and liver transplantation
Acute liver failure: causes, critical care, King's College criteria, and when emergency liver transplantation saves life.Checked against sourcesVerified 31 October 2026Liver abscess and parasitic liver disease
Pyogenic and amoebic liver abscess and hydatid cyst: how they form, how to diagnose, and how to treat them.Checked against sourcesVerified 31 October 2026Cirrhosis
Bridging fibrosis and regenerative nodules: causes, portal hypertension, clinical signs, tests, scores, management and prognosis of cirrhosis.Checked against sourcesVerified 28 October 2026Portal hypertension, ascites and SBP
Portal hypertension and its consequences, cirrhotic ascites and spontaneous bacterial peritonitis: causes, SAAG-based diagnosis, grading and stepwise managementChecked against sourcesVerified 28 October 2026Complications of cirrhosis: HE, HRS and varices
How cirrhosis affects the brain, kidneys, veins and clotting, and how to recognise and manage each complication.Checked against sourcesVerified 28 October 2026Hepatocellular carcinoma and other liver masses
Hepatocellular carcinoma: risks, surveillance, diagnosis, staging with BCLC, treatment, and how other liver masses differ.Checked against sourcesVerified 28 October 2026Hepatic cysts and benign liver lesions
Simple cysts, haemangioma, focal nodular hyperplasia and hepatic adenoma: diagnosis, imaging and management, with cross-check against hepatocellular carcinoma.Checked against sourcesVerified 31 October 2026Acute pancreatitis
Acute pancreatitis: causes from gallstones to alcohol and drugs, Revised Atlanta diagnosis and severity, fluids, feeding, ERCP, and complications.Checked against sourcesVerified 28 October 2026Chronic pancreatitis
Progressive irreversible inflammation and fibrosis of the pancreas causing pain, exocrine insufficiency and diabetes; causes, diagnosis, and treatment.Checked against sourcesVerified 28 October 2026Pancreatic cancer
Pancreatic ductal adenocarcinoma: epidemiology, risk factors, presentation, diagnosis, staging, treatment, screening and prognosis.Checked against sourcesVerified 28 October 2026Pancreatic neuroendocrine tumours: insulinoma and VIPoma
What functioning pancreatic NETs are, how insulinoma and VIPoma present, how they are diagnosed, and how each is treated.Checked against sourcesVerified 28 October 2026