Clinical investigations from the RACP

An approach to the patient with bloody diarrhoea

Corrie Studd, Lindsay Mollison, Romy Nicholson



Bloody diarrhoea is a common, usually benign presentation, but all patients require prompt review. Infective agents, such as Campylobacter species, are the most common causes, although other serious causes include malignancy and bowel ischaemia.

Key Points

  • In the Australian community, diarrhoea alone is a common and usually benign symptom, but the presence of blood is alarming for a patient and will usually prompt a medical review.
  • The most common causes of bloody diarrhoea are infective agents, such as Campylobacter species.
  • The most serious causes of bloody diarrhoea include malignancy, inflammatory bowel disease, bowel ischaemia and complications including sepsis related to severe infection and haemolytic uraemic syndrome.
  • All cases of bloody diarrhoea warrant basic investigation including stool collection and analysis. Further investigation is then case specific.
  • Patients should be referred early to hospital if they are very young, elderly or immunocompromised, or have peritonitis or significant systemic signs of sepsis, shock or dehydration.
  • Review of all patients within 24 to 48 hours should be encouraged, and then again after seven to 10 days to ensure complete resolution of symptoms, and to inform and educate patients regarding culture results.