About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Diverticulosis: presence of diverticula (found in >50% of over-50s — usually asymptomatic, incidental finding)
- Diverticular disease: diverticula causing symptoms. Diverticulitis: acute inflammation/infection of a diverticulum
- Acute diverticulitis: LIF pain + fever + raised CRP/WCC. CT abdomen is gold standard for diagnosis and complications
- Mild/uncomplicated: oral antibiotics (co-amoxiclav 5–7 days). Complicated (abscess/perforation): IV antibiotics ± percutaneous drainage or surgery
- Diverticular bleeding is the commonest cause of MAJOR lower GI bleeding in the elderly — usually painless, often self-limiting
Overview
Diverticulosis is the formation of mucosal and submucosal herniations (false diverticula) through weak points in the colonic muscle wall, typically at sites of penetrating arterioles. The sigmoid colon is most commonly affected (90%). Diverticular disease occurs when diverticula cause symptoms (pain, bleeding, altered bowel habit). Acute diverticulitis results from microperforation of a diverticulum leading to localised inflammation, infection, and potential complications including abscess, free perforation, fistula, and stricture. The Hinchey classification grades the severity of complicated diverticulitis (I–IV).
Epidemiology
Diverticulosis prevalence increases with age: ~30% by age 60, >50% by age 80. It is predominantly a disease of Western populations, associated with low-fibre diets. Approximately 20% of those with diverticulosis will develop symptoms. Acute diverticulitis accounts for approximately 75,000 UK hospital admissions per year. Risk factors include age, low dietary fibre, obesity, smoking, NSAID use, and physical inactivity.
Clinical Features
Symptoms
Left iliac fossa pain (acute diverticulitis — "left-sided appendicitis")
Fever and malaise
Change in bowel habit (constipation or diarrhoea)
Nausea and anorexia
Painless massive rectal bleeding (diverticular haemorrhage — from eroded artery at diverticulum neck)
Pneumaturia or faecaluria (suggests colovesical fistula)
Diffuse abdominal pain with rigidity (free perforation)
Signs
LIF tenderness with localised guarding (acute diverticulitis)
Low-grade pyrexia
Palpable tender LIF mass (phlegmon or abscess)
Generalised peritonitis (free perforation — Hinchey III/IV)
Haemodynamic instability (major diverticular bleed)
Investigations
First-line
FBC, CRP, U&EsRaised WCC and CRP in acute diverticulitis. Severity correlates with CRP level
UrinalysisPneumaturia or mixed organisms suggest colovesical fistula
Second-line
CT abdomen/pelvis with contrastGold standard for acute diverticulitis — shows pericolic fat stranding, bowel wall thickening, abscess, free air, fistula. Hinchey classification based on CT findings
Colonoscopy6–8 weeks AFTER acute episode resolves (NOT during acute diverticulitis — perforation risk). Exclude underlying malignancy
Specialist
CT-guided percutaneous drainageFor diverticular abscess ≥4 cm (Hinchey Ib/II)
CT angiographyFor acute diverticular bleeding if massive and haemodynamically significant
1
Uncomplicated diverticulitis
- Oral antibiotics: co-amoxiclav 625 mg TDS for 5–7 days (or cefalexin + metronidazole if penicillin allergic)
- Clear fluids progressing to normal diet as symptoms improve
- Analgesia: paracetamol (avoid NSAIDs — perforation risk; avoid opioids — reduce motility)
- Most uncomplicated diverticulitis can be managed in the community
2
Complicated diverticulitis
- Admission + IV antibiotics (co-amoxiclav 1.2 g TDS or cefuroxime + metronidazole)
- Abscess <4 cm: IV antibiotics alone (usually resolves)
- Abscess ≥4 cm: CT-guided percutaneous drainage + IV antibiotics
- Free perforation with peritonitis (Hinchey III/IV): emergency Hartmann procedure (sigmoid resection + end colostomy)
- Primary anastomosis with or without defunctioning ileostomy may be considered in selected patients
3
Elective surgery
- Consider after 2+ episodes of complicated diverticulitis, or after single episode with abscess/fistula
- Elective sigmoid colectomy with primary anastomosis (usually laparoscopic)
- Fistula (colovesical, colovaginal): requires resection of affected sigmoid and fistula repair
4
Long-term advice
- High-fibre diet (once acute episode resolved) — reduces recurrence risk
- Adequate hydration, regular exercise
- Stop smoking, maintain healthy weight
Complications
- Pericolic/pelvic abscess: Hinchey I/II — managed with antibiotics ± percutaneous drainage
- Free perforation: Purulent (Hinchey III) or faecal (Hinchey IV) peritonitis — surgical emergency
- Fistula: Colovesical (most common — pneumaturia, recurrent UTIs), colovaginal, coloenteric
- Stricture: From recurrent inflammation — can cause large bowel obstruction
- Diverticular haemorrhage: Painless massive rectal bleeding — usually self-limiting (~80%)
UKMLA Exam Tips
- 1Acute diverticulitis is "left-sided appendicitis" — LIF pain + fever + raised inflammatory markers
- 2Do NOT colonoscope during acute diverticulitis — wait 6–8 weeks (perforation risk). Then scope to exclude cancer
- 3Hinchey classification: I = pericolic abscess, II = pelvic abscess, III = purulent peritonitis, IV = faecal peritonitis
- 4Colovesical fistula: pneumaturia (air in urine) + recurrent polymicrobial UTIs — classic exam presentation
- 5Diverticular bleeding: painless + massive + self-limiting in 80% — commonest cause of major lower GI bleed in elderly
- 6Avoid NSAIDs in diverticular disease — increased perforation risk
practicetest your knowledge on diverticular diseaseApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — gastroenterology and beyond.
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