Quick answer
What is diverticulitis?
Diverticulitis is inflammation or infection of diverticula — small pouches that form in the colon wall, common over age 40. Symptoms include constant lower left abdominal pain, fever, and change in bowel habit. Mild cases treated with antibiotics at home; severe cases need hospital admission. High-fibre diet helps prevent diverticular disease. Seek urgent help for severe pain, vomiting, or inability to pass wind — possible perforation or abscess.
Diverticulitis — when colon pouches flare
Diverticulosis — presence of diverticula (outpouchings of colon mucosa through muscle wall) — very common — 50% over 60 on colonoscopy.
Diverticulitis — inflammation ± infection of diverticula — painful, febrile illness — 5% with diverticulosis experience this.
Diverticulosis vs diverticulitis
| Diverticulosis | Diverticulitis | |
|---|---|---|
| Symptoms | Usually none | Pain, fever, malaise |
| Treatment | High fibre prevention | Antibiotics, sometimes surgery |
| Bleeding | Painless PR bleed possible | Less common |
Symptoms of diverticulitis
Uncomplicated:
- constant LLQ pain — left lower abdomen ( sigmoid colon — Western pattern; right-sided in Asia)
- fever
- change bowel habit — constipation or diarrhoea
- nausea
- tenderness — guarding if severe
Complicated:
- abscess — persistent fever, mass
- perforation — peritonitis — rigid abdomen — A&E
- fistula — colovesical (pneumaturia), colovaginal
- stricture, obstruction
Diagnosis
Clinical + CT abdomen/pelvis with contrast — gold standard — shows wall thickening, fat stranding, abscess
Blood tests — CRP, WCC elevated
Colonoscopy — not during acute attack — 6 weeks post-recovery if first episode age >40 — exclude cancer
Treatment
Uncomplicated — outpatient
Antibiotics covering gut flora:
- co-amoxiclav
- OR ciprofloxacin + metronidazole (if penicillin allergy — local guidance)
Clear liquids → low residue briefly → gradual fibre increase
Paracetamol — avoid NSAIDs early — bleeding risk debate
Some mild cases — antibiotics optional in selected Hinchey 0 — specialist trend — still GP-guided
Complicated — inpatient
- IV antibiotics
- CT-guided drainage — abscess >3cm often
- surgery — Hartmann’s or resection — perforation, failed medical, recurrent
Prevention after recovery
- high-fibre diet — 30g/day target
- hydration
- exercise
- healthy weight
- ** nuts/seeds OK** — myth busted
Diverticulitis vs other causes
| Condition | Clue |
|---|---|
| Appendicitis | RLQ — younger |
| IBS | Chronic pain, no fever |
| Bowel cancer | Weight loss, PR bleed — colonoscopy |
| UTI | Urinary symptoms — colovesical fistula rare |
See bowel cancer if alarm features.
Left lower pain + fever over 40 — same-day assessment — CT confirms — most home antibiotics, some need surgery.
Common questions
- What are the symptoms of diverticulitis?
- Constant abdominal pain — usually left lower quadrant, fever, nausea, constipation or diarrhoea, bloating, blood in stool sometimes. Pain worsens with movement. Unlike diverticulosis which is silent, diverticulitis is painful and systemic illness.
- What causes diverticular disease?
- Low-fibre Western diet increases colon pressure causing pouches (diverticulosis) in weak spots of colon wall. Faecal matter trapping in pouches can cause inflammation and bacterial infection (diverticulitis). Age, obesity, smoking, and inactivity increase risk.
- How is diverticulitis treated?
- Uncomplicated — oral antibiotics (co-amoxiclav or ciprofloxacin + metronidazole), paracetamol not NSAIDs initially, clear fluids progressing to low fibre then high fibre after recovery. Complicated — hospital IV antibiotics, CT scan, abscess drainage, surgery if perforated or recurrent severe episodes.
- Should I avoid nuts and seeds with diverticular disease?
- No — old advice disproven. Nuts, seeds, and popcorn do not cause diverticulitis. When recovered, high-fibre diet reduces recurrence risk. During acute attack, temporary low-fibre diet as advised.
- Does diverticulitis lead to colon cancer?
- Diverticular disease does not cause cancer but symptoms overlap — colonoscopy recommended after first episode in age-appropriate patients or if alarm features — to exclude malignancy. Repeated episodes may lower threshold for colonoscopy.