When to worry about blood in stool with diverticular disease

Small pouches in the bowel wall can bleed suddenly, sometimes without pain. Blood may be bright red or maroon and can appear in the toilet or on stool. Diverticulitis is different: it often causes steady lower abdominal pain, fever, tenderness, nausea, or a change in bowel habit. Bleeding may also come from haemorrhoids, a fissure, inflammation, or another bowel condition, so a known diagnosis of diverticular disease does not explain every episode automatically.

Stop and assess how much bleeding is occurring, whether it is continuing, and whether you have pain, fever, dizziness, or weakness. Keep a note of the colour and any clots. Contact a clinician promptly about new rectal bleeding, especially if you take blood-thinning medicine or have had previous bowel bleeding. Do not stop prescribed medicine or take anti-inflammatory painkillers unless a clinician tells you to.

Seek emergency help for bleeding that is heavy, ongoing, or accompanied by clots; fainting; confusion; pale, sweaty skin; a fast heartbeat; severe or worsening abdominal pain; a rigid or swollen abdomen; fever with marked illness; or repeated vomiting. Black, tar-like stool also needs urgent assessment. Sit or lie down if dizzy, avoid driving yourself, and take a list of medicines with you.

Does the pattern fit diverticular bleeding or diverticulitis? Could another source be responsible? Do I need an examination, blood tests, imaging, or a bowel procedure? Which warning signs should make me return immediately, and how should I manage blood-thinning medicine?