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Probability diagnosis

Haemorrhoids/perianal haematoma

Anal fissure

Colorectal polyp


Excoriated skin (anal pruritus)

Serious disorders not to be missed


  • ischaemic colitis

  • angiodysplasia (vascular ectasia)

  • anticoagulant therapy


  • enteritis (e.g. Campylobacter, Salmonella)


  • colorectal, caecum

  • lymphoma

  • villous adenoma


  • inflammatory bowel disease (colitis/proctitis)

  • intussusception

Pitfalls (often missed)

Rectal prolapse

Anal trauma (accidental/non-accidental)

Villous adenoma


  • Meckel diverticulum

  • solitary ulcer of rectum

Key history

Nature of the bleed, including fresh versus altered blood, mixed with faeces and/or mucus, in toilet bowl or on underwear. Quantity of bleeding: slight, moderate or torrential. Associated symptoms (e.g. weight loss, constipation, diarrhoea, pain, weakness, presence of lumps, urgency, unsatisfied defecation, recent change of bowel habit).

Key examination

  • General inspection (evidence of anaemia) and vital signs

  • Abnormal examination, anal inspection, digital rectal examination, proctosigmoidoscopy

Key investigations

  • FBE and ESR

  • Stool M&C

  • Faecal occult blood

  • Colonoscopy

  • Consider abdominal X-ray, CT colonography, angiography, small bowel enema (depending on clinical findings)

Diagnostic tips

  • Black, tarry (melaena) stool indicates bleeding from upper GIT: rare distal to lower ileum.

  • Frequent passage of blood and mucus indicates a rectal tumour or proctitis.

  • If substantial haemorrhage, consider diverticular disease, angiodysplasia or more proximal lesions (e.g. Meckel diverticulum, duodenal ulcers).

  • New bleeding age >55 years demands colonic investigation.

  • 80% of rectal tumours are within fingertip range.

  • In young adults, diagnosis is likely to be haemorrhoids or a fissure.

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