Diverticular Disease — Diverticulosis, Diverticulitis and When to Investigate

TL;DR — Diverticular disease is when small pouches (diverticula) form in the wall of the colon. It is extremely common — affecting around 50% of Australians by age 60 — and most people with it have no symptoms. The clinical issues arise when diverticula become inflamed (diverticulitis), bleed, or cause chronic symptoms. Diagnosis is usually by colonoscopy (when stable) or CT scan (in the acute setting). Most cases are managed with dietary fibre and watchful waiting; some need antibiotics, and a small minority need surgery.

What is diverticular disease?

Diverticula are small (typically 5–10 mm) outpouchings of the inner lining of the colon that push through weak spots in the muscular wall. They most commonly occur in the sigmoid colon — the section just before the rectum — but can appear anywhere along the large bowel.

The condition has three terms worth distinguishing:

• Diverticulosis — the presence of diverticula without symptoms (very common, usually an incidental finding at colonoscopy).
• Diverticular disease — chronic symptoms thought to be due to diverticula (cramping, change in bowel habit, bloating).
• Diverticulitis — acute inflammation of one or more diverticula, with fever, focal abdominal pain (usually the left lower quadrant), and raised inflammatory markers.

Symptoms

Most people with diverticulosis have no symptoms. When symptoms do occur, they can include:

• Intermittent cramping in the lower left abdomen
• Change in bowel habit — constipation, diarrhoea, or alternating
• Bloating
• In acute diverticulitis: focal left-lower-quadrant pain, fever, nausea, change in bowel habit, sometimes urinary symptoms.
• In diverticular bleeding: painless passage of bright red or maroon blood per rectum, often substantial in volume.

Causes and risk factors

• Age — prevalence rises from around 10% at age 40 to over 50% by age 60.
• Low-fibre diet — long thought to be the main driver; the evidence is now more nuanced, but a high-fibre diet remains protective.
• Obesity, sedentary lifestyle and smoking.
• Chronic NSAID use — associated with both diverticulitis and diverticular bleeding.
• Genetic predisposition — diverticular disease clusters in families.

How is diverticular disease diagnosed?

• Colonoscopy — the test of choice for diagnosing diverticulosis in the stable setting; also rules out other causes of symptoms such as polyps and bowel cancer.
• CT scan — the test of choice in suspected acute diverticulitis; identifies inflammation, abscess, perforation and fistula.
• Blood tests — full blood count, CRP, and ferritin (to exclude anaemia from bleeding).

Colonoscopy is generally not performed during acute diverticulitis because of the risk of perforating an inflamed diverticulum. It is usually deferred 6–8 weeks after the acute episode has resolved.

How is diverticular disease treated?

• Asymptomatic diverticulosis — no treatment needed beyond a high-fibre diet (25–30 g/day) and adequate fluid intake. The old advice to avoid nuts and seeds has been overturned: they do not cause diverticulitis.
• Symptomatic diverticular disease without inflammation — high-fibre diet, fibre supplementation (psyllium), antispasmodics for cramping, and addressing constipation.
• Mild diverticulitis — recent guidelines support managing many mild cases without antibiotics in selected patients (low-grade inflammation, no abscess, no significant comorbidity). Others receive oral antibiotics and a temporary clear-fluid diet.
• Severe diverticulitis — hospital admission, IV antibiotics, sometimes drainage of an abscess; surgery if there is perforation, peritonitis, or recurrent severe attacks.
• Diverticular bleeding — most stops spontaneously. Colonoscopy and/or CT angiography are used to identify the source; embolisation or surgery is rarely required.

When to see a specialist

• Significant rectal bleeding — always needs investigation.
• After an episode of diverticulitis — colonoscopy is recommended 6–8 weeks later to exclude other diagnoses.
• Recurrent diverticulitis or unresolving symptoms.
• Chronic abdominal pain attributed to diverticular disease — deserves confirmation by colonoscopy.
• Iron-deficiency anaemia — even if diverticulosis is known, the anaemia should be independently investigated.

What to expect at your appointment with Dr Goutham

Dr Goutham will take a focused history (bleeding pattern, prior episodes, current symptoms, current medications including NSAIDs and antiplatelets) and review any previous imaging or pathology.

Colonoscopy is the usual next step in stable patients — both to confirm diverticulosis and to rule out other causes of the symptoms. The procedure takes 20–40 minutes under sedation; results are discussed on the day with images where relevant. A written report goes to your GP within 48 hours.

Frequently asked questions

Should I avoid nuts, seeds and popcorn?

No. The old advice to avoid small particulate foods has been disproven. Large studies have shown that nut, seed and popcorn intake is associated with a lower risk of diverticulitis, not higher. A high-fibre diet that includes nuts and seeds is protective.

Does diverticular disease lead to bowel cancer?

No, diverticular disease does not cause bowel cancer. However, the symptoms can overlap, which is why colonoscopy after a first episode of diverticulitis is important — it distinguishes between the two.

If I have diverticulosis but no symptoms, do I need follow-up?

No specific follow-up is needed for diverticulosis itself. The usual bowel-cancer surveillance schedule (based on findings at colonoscopy — see the surveillance intervals page) applies as normal.

Book a consultation

Phone 07 3733 1551 or send a referral via the contact form. No-gap colonoscopy for insured patients across Brisbane, Redland and Logan. Read more about Dr Goutham or see the cost page.