Rectal bleeding

Probability diagnosis

Haemorrhoids/perianal haematoma

Anal fissure

Colorectal polyp

Diverticulitis

Excoriated skin (anal pruritus)

Serious disorders not to be missed

Vascular:

• ischaemic colitis

• angiodysplasia (vascular ectasia)

• anticoagulant therapy

Infection:

• enteritis (e.g. Campylobacter, Salmonella)

Cancer/tumours:

• colorectal, caecum

• lymphoma

• villous adenoma

Other:

• inflammatory bowel disease (colitis/proctitis)

• intussusception

Pitfalls (often missed)

Rectal prolapse

Anal trauma (accidental/non-accidental)

Villous adenoma

Rarities:

• 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.