Rectal Bleeding in Adults

This is a very common presenting complaint and creates a lot of anxiety in the patient. By far the likeliest causes are haemorrhoids or a fissure, but more sinister pathologies should be considered according to the clinical picture, especially in older patients.

Published: 1st August 2022 | Updated: 21st September 2022

Differential diagnosis

Common Diagnoses

  • Haemorrhoids
  • Anal Fissure
  • Gastroenteritis
  • Rectal Carcinoma
  • Diverticular Disease

Occasional Diagnoses

  • Villous Adenoma
  • Trauma
  • Anticoagulant Therapy
  • Inflammatory Bowel Disease
  • Colonic Carcinoma

Rare Diagnoses

  • Blood Clotting Disorders (Including Anticoagulants)
  • Bowel Ischaemia
  • Angiodysplasia
  • Intussusception

Ready reckoner

Key distinguishing features of the most common diagnoses

PilesFissureGastroenteritisCancer of RectumDiverticulosis
Blood and Stool MixedNoNoYesNoPossible
Abdominal PainNoNoYesNoPossible
Mass Felt PRPossibleNoNoYesPossible
Sentinel anal Skin TagNoYesNoNoNo

Possible investigations

Likely: Proctoscopy.

Possible: FBC, ESR/CRP, LFTs, bone biochemistry, U&E, stool for microbiology and faecal calprotectin, FIT, hospital-based lower GI investigations.

Small Print: Clotting screen.

  • FBC: Check for anaemia from acute or chronic bleeding; low platelets may cause or aggravate bleeding
  • ESR/CRP raised in active inflammatory bowel disease and malignancy
  • If malignancy is suspected, LFT, U&E and bone biochemistry are useful early on as a baseline
  • Clotting screen: If clotting disorder a possibility; INR if on warfarin.
  • Stool specimen: Helpful in the presence of diarrhoea. May show evidence of infective cause (especially Campylobacter) or white cells in inflammatory bowel disease. Faecal calprotectin may be useful in diagnosing IBD. FIT: A useful colorectal cancer ‘rule out’ test in patients at low risk, also commonly required when arranging a two-week referral to help secondary care stratify urgency of investigation.
  • Proctoscopy: Helpful in primary care in visualising haemorrhoids and proctitis to confirm a clinical diagnosis.
  • Hospital-based lower GI investigations: Necessary if significant pathology is suspected.

Top Tips

  • Eighty percent of rectal tumours are within fingertip range. Always do a PR examination unless the diagnosis is manifestly obvious from the history.
  • If blood is on the toilet paper and surface of the motions, the cause is likely to be palpable PR or visible on proctoscopy; if mixed in with the motions, referral for further investigation will be required to make a definite diagnosis.
  • In young adults, the diagnosis is usually clear from the history and is likely to be haemorrhoids or a fissure. In such cases, if and when you refer, to allay anxiety, emphasise that this is for treatment rather than investigation.
  • The presence of diarrhoea with rectal bleeding in young adults suggests gastroenteritis (especially Campylobacter) or colitis.

Red Flags

  • Change of bowel habit and weight loss with rectal bleeding are ominous symptoms which should prompt urgent referral.
  • Any patient aged 50 or over with unexplained rectal bleeding merits urgent referral to rule out cancer.
  • The presence of haemorrhoids does not necessarily clinch the diagnosis – another lesion may be present, especially in the elderly.
  • A brisk, painless haemorrhage in an elderly patient is likely to be caused by diverticular disease. Significant amounts of blood can be lost, so assess urgently with a view to admission
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Website disclaimer

Pulse Reference is based on the best-selling book Symptom Sorter.

The experts behind Pulse Reference are Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse’s editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.

This website is for clinical guidance only and cannot give definitive diagnostic information. Practitioners should work within the limits of their individual professional practice, seek guidance when necessary and refer appropriately.