Gastroenterology
Browse 104 topics in gastroenterology, including presentations, diagnoses, procedures, tools, and exam links.
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Use the filters below to move between emergency clusters, core pathways, exam topics, procedures, and the most relevant clinical atlas pages.
Achalasia
The diagnosis has been refined by High-Resolution Manometry (HRM) and the Chicago Classification (v4.0) , which divides the disease into three distinct phenotypic patterns (Types I, II, and III) with significant...
Acute Cholangitis
Acute cholangitis is a life-threatening systemic infection arising from bacterial contamination of an obstructed biliary... MRCP, FRACS exam preparation.
Acute Cholecystitis
Acute cholecystitis is an acute inflammatory condition of the gallbladder, most commonly resulting from cystic duct obst... MRCS exam preparation.
Acute Constipation
Management follows a stepwise "Laxative Ladder" approach, prioritizing lifestyle modification and osmotic laxatives (Macrogol) over stimulants. Identifying Opioid-Induced Constipation (OIC) is critical in acute...
Acute Diarrhoea and Gastroenteritis
Acute diarrhoea is defined as the passage of three or more loose or watery stools per day (or more frequent than normal for the individual) lasting less than 14 days . It is a leading cause of outpatient visits and...
Acute Diverticulitis
Diagnosis is primarily confirmed by CT abdomen/pelvis with intravenous contrast, which demonstrates pericolic fat stranding, bowel wall thickening, and complications such as abscess or perforation. The modified...
Acute Gastritis and Gastropathy
The primary aetiologies include Helicobacter pylori infection, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), alcohol, and severe physiological stress (e.g., in ICU). The Maastricht VI/Florence Consensus (2022)...
Acute Hepatitis
The majority of cases are self-limiting; however, a small percentage can progress to Acute Liver Failure (ALF) , defined by the development of coagulopathy (INR ≥1.5) and encephalopathy. Management is primarily...
Acute Liver Failure
Key Facts The Definition Triad : 1. Acute onset (less than 26 weeks), 2. Coagulopathy (INR ≥1.5), 3. Encephalopathy. The "Killer" Mechanism : Cerebral oedema leading to brainstem herniation is the most common cause of...
Acute Lower GI Bleeding
Acute lower gastrointestinal bleeding (LGIB) is a medical emergency characterized by bleeding from the gastrointestinal tract distal to the ligament of Treitz, presenting as hematochezia (bright red or maroon blood...
Acute Oesophagitis
Acute oesophagitis represents sudden-onset inflammation of the oesophageal mucosa, most commonly secondary to gastro-oes... MRCP exam preparation.
Acute Pancreatitis
Acute Pancreatitis (AP) is an acute inflammatory process of the pancreas with variable involvement of other regional tis... MRCP exam preparation.
Acute Severe Ulcerative Colitis (ASUC)
The management of ASUC is a race against time. The "Three-Day Rule" is the cornerstone of modern care: failure to demonstrate a significant biological response to high-dose intravenous corticosteroids by Day 3...
Acute-on-Chronic Liver Failure (ACLF)
Key Facts Incidence : Occurs in 25–35% of patients hospitalized for acute decompensation of cirrhosis. Mortality : 28-day mortality ranges from 23% (Grade 1) to 75% (Grade 3). Pathophysiology : Massive systemic...
Alcohol Dependence (Alcohol Use Disorder)
Alcohol Use Disorder (AUD), previously termed alcohol dependence, is a chronic, relapsing neurobiological condition characterised by compulsive alcohol seeking and use despite harmful consequences, impaired control...
Alcohol Dependence & Withdrawal
Alcohol use disorder (AUD) is a chronic, relapsing neurobiological condition characterised by compulsive alcohol consump... MRCPsych exam preparation.
Alcohol-Related Liver Disease (ALD)
Alcohol-Related Liver Disease (ALD) encompasses the full spectrum of hepatic injury caused by chronic excessive alcohol ... MRCP exam preparation.
Alpha-1 Antitrypsin Deficiency
Alpha-1 Antitrypsin Deficiency (AATD) is an autosomal codominant genetic disorder caused by mutations in the SERPINA1 ge... MRCP exam preparation.
Amoebiasis (Amoebic Dysentery)
Amoebiasis is a parasitic infection caused by the protozoan Entamoeba histolytica, transmitted via the faecal-oral route... MRCP exam preparation.
Anal Fissure
An anal fissure is a longitudinal tear in the squamous epithelium (anoderm) of the anal canal, extending from the dentat... FRCS exam preparation.
Ascending Cholangitis
Ascending Cholangitis is a life-threatening bacterial infection of the biliary tree, classically occurring in the settin... MRCP exam preparation.
Ascites and Spontaneous Bacterial Peritonitis
Ascites is the pathological accumulation of fluid in the peritoneal cavity, occurring in 50% of patients with compensated cirrhosis within 10 years of diagnosis. It represents a critical transition from compensated to...
Ascites in Adults
Ascites is the pathological accumulation of fluid within the peritoneal cavity. It represents a cardinal manifestation of decompensated cirrhosis and portal hypertension, though diverse aetiologies including...
Autoimmune Hepatitis (Adult)
Autoimmune hepatitis (AIH) is a chronic, progressive inflammatory liver disease characterised by the triad of interface ... MRCP, USMLE exam preparation.
Barrett's Oesophagus
It represents an adaptive response to chronic gastro-oesophageal reflux disease (GORD) and is the single most important precursor lesion for oesophageal adenocarcinoma (OAC), which has shown a dramatic increase in...
Biliary Atresia
The hallmark presentation is conjugated hyperbilirubinaemia with persistent jaundice beyond the physiological neonatal period, accompanied by acholic (pale) stools and dark urine. Early diagnosis is critical because...
Biliary Colic & Acute Cholecystitis
Biliary colic and acute cholecystitis represent a clinical spectrum of gallstone-related disease affecting the gallbladder. Biliary colic is transient right upper quadrant (RUQ) pain caused by temporary cystic duct...
Carcinoid Syndrome and Neuroendocrine Tumours
Neuroendocrine tumours (NETs) represent a heterogeneous group of neoplasms arising from neuroendocrine cells distributed... MRCP exam preparation.
Chagas Disease (American Trypanosomiasis)
Chagas disease is a potentially life-threatening systemic parasitic infection caused by the protozoan hemoflagellate Try... MRCP exam preparation.
Chronic Liver Disease and Cirrhosis
Chronic Liver Disease (CLD) represents a spectrum of progressive liver injury and fibrosis, culminating in Cirrhosis . Cirrhosis is defined histologically as diffuse hepatic fibrosis with the formation of regenerative...
Chronic Pancreatitis
The clinical hallmark is chronic abdominal pain, which affects 80-90% of patients and significantly impairs quality of life. As the disease progresses, patients develop exocrine pancreatic insufficiency (EPI)...
Clostridioides difficile Infection
Key Facts Pathogen : Toxin-producing Clostridioides difficile (formerly Clostridium difficile) Toxins : Toxin A (enterotoxin), Toxin B (cytotoxin, 10-100x more potent), Binary toxin CDT (hypervirulent strains)...
Coeliac Disease (Adult)
Coeliac disease is a chronic, immune-mediated enteropathy triggered by the ingestion of dietary gluten in genetically su... MRCP exam preparation.
Coeliac Disease in Adults
Coeliac disease is a chronic, immune-mediated systemic disorder triggered by dietary gluten in genetically predisposed i... MRCP exam preparation.
Colonic Polyps
Colonic polyps are abnormal tissue growths that protrude from the colonic mucosa into the bowel lumen. They represent a ... MRCP exam preparation.
Colorectal Cancer
The disease demonstrates significant geographical variation in incidence, with highest rates observed in developed countries, reflecting the impact of dietary factors, sedentary lifestyle, and increased longevity....
Constipation (Adult)
Constipation is a highly prevalent gastrointestinal disorder characterised by infrequent bowel movements, difficulty passing stools, or a sensation of incomplete evacuation. It affects approximately 16% of adults...
Crohn's Disease
Crohn's disease is a chronic, relapsing-remitting inflammatory bowel disease (IBD) characterised by transmural inflammat... MRCP exam preparation.
Cystic Fibrosis in Children
Cystic fibrosis (CF) is the most common life-limiting autosomal recessive disorder affecting Caucasian populations, with... MRCPCH exam preparation.
Drug-Induced Liver Injury
Pattern classification is fundamental: hepatocellular (ALT-predominant), cholestatic (alkaline phosphatase-predominant), or mixed, determined by the R-ratio: (ALT/ULN) ÷ (ALP/ULN). R ≥5 indicates hepatocellular...
Dyspepsia (Adult)
Dyspepsia is defined as epigastric pain or burning, postprandial fullness, or early satiation . It affects 10-40% of the global population , making it one of the most common reasons for gastroenterology consultations....
Eating Disorders (Anorexia, Bulimia & BED)
Anorexia Nervosa (AN): Restriction of energy intake leading to low body weight. Intense fear of gaining weight. Disturbance in body image.
Gallstones (Cholelithiasis)
The pathophysiology centres on supersaturation of bile with cholesterol or bilirubin, leading to nucleation and crystal aggregation. Approximately 75-80% of gallstones are cholesterol stones, while 15-20% are pigment...
Gastric Cancer
The strongest modifiable risk factor is chronic infection with Helicobacter pylori , classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC). Other significant risk factors include...
Gastritis
The most clinically significant forms are Type B (bacterial) gastritis caused by Helicobacter pylori infection and Type A (autoimmune) gastritis associated with parietal cell antibodies. Chronic gastritis represents a...
Gastritis and Peptic Ulcer Disease
Comprehensive evidence-based review of gastritis and peptic ulcer disease, including pathophysiology, diagnosis, H. pylori eradication, and management of complications
Gastro-Oesophageal Reflux Disease
Gastro-oesophageal reflux disease (GORD) is defined as a condition that develops when reflux of gastric contents causes ... MRCP, USMLE exam preparation.
Gastro-Oesophageal Reflux Disease (GORD)
GORD represents one of the most common gastrointestinal disorders in Western populations, with significant impact on quality of life and healthcare costs. The condition exists on a spectrum from Non-Erosive Reflux...
Gastroparesis
The cardinal symptoms are nausea ( 90%), vomiting (particularly of undigested food hours after eating), early satiety , postprandial fullness , bloating , and abdominal pain . These symptoms are often debilitating and...
Giardiasis
Transmission occurs primarily via the fecal-oral route through ingestion of infectious cysts in contaminated water, food, or via person-to-person contact. The infection is particularly prevalent among travelers to...
Gilbert's Syndrome
Gilbert's Syndrome (GS) is a common, benign, hereditary condition characterized by mild, intermittent unconjugated hyper... MRCP, USMLE exam preparation.
Glucagonoma
Dermatosis – Necrolytic Migratory Erythema (NME) Diabetes Mellitus – usually mild to moderate Deep Vein Thrombosis – hypercoagulable state Depression – neuropsychiatric manifestations
Haemorrhoids (Adult)
A comprehensive, evidence-based clinical guide to haemorrhoids (piles) for postgraduate surgical training. Covers anatomy, Goligher classification, office-based treatments (rubber band ligation, sclerotherapy),...
Helicobacter Pylori
Key Facts Global Prevalence : 4.4 billion people infected worldwide (58% of global population), with marked geographic variation (20-30% in developed nations, 70-90% in developing countries). Discovery : Nobel Prize...
Hepatic Encephalopathy
The clinical course is typically episodic, often precipitated by identifiable triggers including infection (particularly spontaneous bacterial peritonitis), gastrointestinal bleeding, constipation, electrolyte...
Hepatic Encephalopathy in Adults
Comprehensive evidence-based guide to hepatic encephalopathy diagnosis, classification, and management in adults with chronic liver disease
Hepatic Failure Pathology
Acute liver failure (ALF) is defined as severe hepatic dysfunction with coagulopathy (INR ≥1.5) and encephalopathy in a patient without pre-existing liver disease, developing within 26 weeks of symptom onset....
Hepatitis A
The disease demonstrates significant geographic variation in endemicity, with high prevalence in regions with poor sanitation and hygiene infrastructure. In developed countries, most cases are imported through...
Hepatitis B (Adult)
Hepatitis B virus (HBV) is a partially double-stranded DNA hepatotropic virus of the Hepadnaviridae family that causes both acute and chronic liver disease. Unlike other hepatitis viruses, HBV establishes a persistent...
Hepatitis C
Transmission occurs predominantly via parenteral exposure : injection drug use (IVDU), blood transfusions prior to universal screening (pre-1992 in the UK, pre-1990 in the USA), needlestick injuries, vertical...
Hepatocellular Carcinoma (HCC)
The major risk factors are chronic viral hepatitis (hepatitis B virus [HBV] and hepatitis C virus [HCV]), alcohol-related liver disease, and increasingly non-alcoholic steatohepatitis (NASH), now termed metabolic...
Hepatorenal Syndrome (HRS)
HRS occurs almost exclusively in the context of decompensated cirrhosis with ascites, though it can occasionally complicate acute liver failure and alcoholic hepatitis. The syndrome carries an extremely poor...
Hereditary Haemochromatosis
Hereditary haemochromatosis (HH) is an autosomal recessive disorder of iron metabolism characterized by excessive intest... MRCP exam preparation.
Hiatus Hernia
The condition exists on a spectrum from incidental radiological findings to symptomatic disease requiring surgical correction. Type I (sliding) hernias account for approximately 95% of cases and are primarily...
Hirschsprung's Disease
A comprehensive, evidence-based guide to Hirschsprung's Disease covering molecular genetics (RET proto-oncogene), neural crest migration failure, diagnostic approaches including rectal suction biopsy and anorectal...
Hypomagnesaemia
The most important clinical consequences include life-threatening ventricular arrhythmias (particularly Torsades de Pointes), neuromuscular irritability (tetany, seizures), and electrolyte disturbances that cannot be...
Inflammatory Bowel Disease (IBD)
Inflammatory Bowel Disease (IBD) comprises two principal chronic, immune-mediated inflammatory disorders of the gastroin... MRCP, USMLE exam preparation.
Inflammatory Bowel Disease (IBD) in Adults
Inflammatory Bowel Disease (IBD) comprises a group of chronic, immune-mediated inflammatory conditions of the gastrointe... MRCP exam preparation.
Insulinoma
Over 90% of insulinomas are benign, solitary, and less than 2 cm in diameter . Approximately 5-10% are associated with Multiple Endocrine Neoplasia Type 1 (MEN1) , where they may be multiple. Malignancy occurs in...
Intrahepatic Cholestasis of Pregnancy (Obstetric Cholestasis)
Intrahepatic cholestasis of pregnancy (ICP), also known as obstetric cholestasis, is the most common pregnancy-specific liver disorder, characterised by pruritus and elevated serum bile acids. It typically presents in...
Irritable Bowel Syndrome
Diagnosis is clinical, based on the Rome IV criteria, which require recurrent abdominal pain at least 1 day per week in the last 3 months, associated with two or more of: (1) related to defecation, (2) associated with...
Irritable Bowel Syndrome (IBS)
IBS is not a diagnosis of exclusion, but rather a positive clinical diagnosis based on symptom-based criteria (Rome IV) combined with judicious use of investigations to exclude alarm features. The pathophysiology is...
Liver Cirrhosis
Liver Cirrhosis is the histological end-stage of diverse chronic liver insults, characterised by diffuse hepatic fibrosi... MRCP exam preparation.
Mallory-Weiss Tear
A Mallory-Weiss tear is a longitudinal mucosal or submucosal laceration occurring at or near the gastro-oesophageal junction (GOJ), typically caused by a sudden and forceful increase in intra-abdominal pressure...
Meckel's Diverticulum
Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract, representing a persistent rem... MRCS, MRCPCH exam preparation.
Mesenteric Ischaemia
Key Facts Incidence : Acute: 0.1-0.2% of acute surgical admissions; Chronic: Rare (less than 1 per 100,000). Mortality : Acute: 30-90% (highest of abdominal emergencies); Chronic: less than 5% with treatment. Age...
Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)
Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), formerly known as Non-Alcoholic Fatty Liver Disease (N... MRCP exam preparation.
Non-Alcoholic Fatty Liver Disease (NAFLD / MASLD)
Non-Alcoholic Fatty Liver Disease (NAFLD), recently renamed Metabolic Dysfunction-Associated Steatotic Liver Disease (MA... MRCP Part 2 exam preparation.
Oesophageal Cancer (Adult)
Oesophageal cancer is a highly aggressive malignancy of the oesophagus with two distinct histological subtypes: adenocar... MRCP, FRCS exam preparation.
Oesophageal Varices
Approximately 50% of patients with cirrhosis have varices at the time of diagnosis , with the prevalence increasing to 60-80% in those with decompensated cirrhosis. The annual incidence of new varix formation is 5-8%...