Eligible asymptomatic people aged 45–74 can use the National Bowel Cancer Screening Program’s at-home iFOBT every two years. Symptoms need clinical investigation.

Testing may use a breath test, blood test, stool sample or endoscopy. H. pylori can cause gastritis and peptic ulcers; treatment heals most peptic ulcers and reduces stomach-cancer risk.

Consider and rule out other illnesses. IBS commonly features pain, bloating and diarrhoea, constipation or both; routine tests do not show the bowel inflammation seen in IBD.

Use enteral rehydration—oral or nasogastric—whenever possible. Most children do not need investigations; vomiting without diarrhoea or red flags should trigger consideration of another diagnosis.

It examines the large bowel and can allow therapeutic interventions, including polyp removal and tissue sampling. It is used to investigate suspected bowel disease and cancer.

Pain often starts near the umbilicus, then moves to the right lower abdomen and becomes more severe and constant. Fever, nausea, vomiting and reduced appetite may accompany it.

Dysphagia or painful swallowing, persistent/new reflux, food sticking or regurgitation, unexplained weight loss, fatigue, haematemesis or melaena merit prompt clinical assessment.

Sudden severe abdominal pain, worse with movement, with a hard or swollen abdomen, fever or vomiting is an emergency. Peritonitis may follow a burst appendix or other organ.

It may arise from a distal source such as haemorrhoids or fissure, but the cause is not certain from colour alone. Rectal bleeding should be assessed.

Heartburn and regurgitation are the common symptoms. Dysphagia or persistent symptoms should prompt consideration of complications or alternative diagnoses.

Weak pelvic floor muscles can contribute to faecal leakage. Other contributors include childbirth injury, constipation, diarrhoea, nerve problems and anorectal disease.

Difficulty passing stool, hard/lumpy motions, straining and incomplete emptying are typical. Bowel frequency varies; a daily motion is not required for everyone.

Haematemesis is vomiting blood; melaena is black, tarry stool. They may indicate upper GI bleeding. Emergency assessment is needed for haematemesis, melaena or bleeding with weakness/light-headedness.

Rectal bleeding, a change in usual bowel habit, abdominal pain or bloating, unexplained weight loss/appetite loss, or symptoms of anaemia. Symptoms do not prove cancer, but require review.

Gluten restriction can reduce test accuracy. Use coeliac serology while the patient eats gluten; positive serology alone does not confirm disease. Specialist assessment and small-bowel biopsy are important.

Crohn’s can affect any part of the digestive tract and involves the full bowel-wall thickness. Ulcerative colitis affects the inner lining of the colon and rectum.

Diverticulosis is colonic pouches; diverticular disease is symptomatic diverticulosis; diverticulitis is inflammation or infection of a pouch.