Rectal Bleeding

Differentials

Most Common

• Diverticulosis

• Haemorrhoids

Other Causes

• Anal Fissure

• Colorectal Cancer or Polyp

• Infectious Colitis (Campylobacter, Shigella, Salmonella, EHEC)

• Ischaemic Colitis

• Angiodysplasia

• Inflammatory Bowel Disease (Ulcerative Colitis, Crohn’s Disease)

• Anal Cancer or Polyp

• Peptic Ulcer/Gastritis (rarely presents with bright red bleeding, more typically melena)

• Coagulopathy (e.g. warfarin, DOAC use)

• Oesophagitis/Oesophageal Varices (more commonly melena or haematemesis)

History Questions

• Medication Use: Anticoagulants (warfarin, DOACs), antiplatelets, NSAIDs

• Bowel Habit Changes: Diarrhoea, constipation, changes in calibre/frequency

• Character/Colour of Blood: Bright red vs. mixed with stool vs. melena

• Fever: Suggestive of infection or IBD flare

• Cardiovascular: Palpitations, hypotension if significant blood loss

• Weight Loss, family history of bowel cancer (red flag)

• Perianal Symptoms: Pruritus, lumps (haemorrhoids), painful defecation (anal fissures)

• Abdominal Pain: Nocturnal diarrhoea, urgency → IBD, or postprandial pain → ischaemic colitis

• Travel History, recent antibiotics, undercooked foods → Infectious colitis/gastroenteritis

• Previous Investigations: Recent colonoscopy or FOBT results

Investigations

1. Blood Tests

   • FBC: Anaemia?

   • ELFTs: Electrolytes, renal/liver function

   • CRP: Inflammatory markers (IBD, infection)

   • Coagulation Profile, Iron Studies if suspect chronic blood loss

2. Imaging

   • CT Abdomen/Pelvis with contrast if malignancy or diverticular disease suspected

3. Endoscopic Evaluation

   • Flexible Sigmoidoscopy for suspected left-sided pathology (e.g. haemorrhoids, rectal disease, distal colitis)

   • Colonoscopy if red flags are present or suspicion of proximal lesions

   • No indication for FOBT if actively symptomatic

Red Flags

• Age >50 years, new-onset bleeding

• Age <50 with additional risk factors:

  • Unexplained abdominal pain

  • Change in bowel habit

  • Weight loss

  • Iron deficiency

  • Family History of bowel cancer

  • Persistent symptoms >6 weeks

Management Guidelines

• Identify Source: Thorough physical exam (digital rectal exam, proctoscopy) and ensure no suspicious lesions.

• No Need for Scope if:

  • Age <40, bright red rectal bleeding, and clear benign cause on exam (e.g. haemorrhoids, fissure), no other risk factors.

• Scope Required if:

  • Age >40, or

  • Presence of red flags (weight loss, anaemia, persistent changes), or

  • Uncertain diagnosis.

Iron Deficiency Anaemia requires investigation of GI tract bleeding, especially in men or postmenopausal women.

Notes

• Assess severity of bleeding (haemodynamic stability, repeated episodes).

• Treat underlying cause: e.g. haemorrhoids (topical agents, banding), diverticular disease (diet/fibre, possible surgical consult if recurrent bleeds), IBD management.

• Refer for colonoscopy if suspicion of polyp, cancer, or persistent unexplained rectal bleeding.