Rectal Bleeding in Adults
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
| Piles | Fissure | Gastroenteritis | Cancer of Rectum | Diverticulosis | |
|---|---|---|---|---|---|
| Blood and Stool Mixed | No | No | Yes | No | Possible |
| Abdominal Pain | No | No | Yes | No | Possible |
| Diarrhoea | No | No | Yes | No | Yes |
| Mass Felt PR | Possible | No | No | Yes | Possible |
| Sentinel anal Skin Tag | No | Yes | No | No | No |
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