Diverticular Disease
This article explains three closely related but distinct conditions:
- Diverticulosis: presence of diverticula in the colon wall, without symptoms
- Diverticular disease: diverticula causing local symptoms (not systemic symptoms)
- Acute diverticulitis: inflammation or infection of diverticula
Diverticula are small outpouchings or sacs in the colon wall due to herniation through weak spots.
Diverticulosis
Anatomy
Diverticula mainly arise in the distal colon, with sigmoid colon involvement in 90% cases. [Ref]
Aetiology
Key risk factors: [Ref]
- >65 y/o – most significant risk factor
- Male sex
- Obesity
- Smoking and alcohol use
- Genetic factors
Note that constipation and low fibre intake are implicated in the progression and complications of diverticular disease, but NOT in the initial development of diverticulosis. [Ref]
Clinical Features
Diverticulosis is asymptomatic. It is typically discovered incidentally
If diverticulosis causes symptoms, it is termed diverticular disease.
Complications
Progression to diverticular disease and acute diverticulitis
Investigation and Diagnosis
Since diverticulosis is asymptomatic, it is usually detected incidentally by:
- Colonoscopy (allows direct visualisation of the diverticula, including their number, location and extent)
- CT abdomen and pelvis
Management
No specific treatment is needed.
Provide the following advice:
- Eat a healthy, balanced diet (including whole grains, fruit and vegetables)
- Weight loss, smoking cessation and regular physical activity can reduce the risk of progression into diverticular disease and acute diverticulitis
If the patient experiences constipation:
- Increase dietary fibre and fluid intake
- Consider a bulk-forming laxative
Diverticular Disease
Aetiology
Similar to those of diverticulosis (mainly >65 y/o, male sex, obesity, smoking)
But also a low fibre diet and constipation.
Clinical Features
Diverticular disease has a chronic / recurrent disease course:
- Intermittent left iliac fossa abdominal pain
- The pain may be triggered by eating and relieved by defecation
- Rectal bleeding
- Concurrent constipation is common
- IBS-like symptoms (passing mucus, urgency, change in bowel habit) are common
Diverticular disease is differentiated from acute diverticulitis by the absence of systemic inflammatory signs and normal inflammatory laboratory markers.
Investigation and Diagnosis
NICE states that they are unable to make a recommendation regarding tests for diverticular disease:
- Patients will often be investigated by endoscopy (flexible sigmoidoscopy / colonoscopy) or CT colonography
If acute diverticulitis is suspected: perform CT abdomen-pelvis (see below for more details)
Diverticular disease is differentiated from acute diverticulitis by the absence of systemic inflammatory signs and normal inflammatory laboratory markers.
The differentiation between diverticular disease and acute diverticulitis can be hard. If in doubt, perform investigations to exclude acute diverticulitis (see below).
Management
Offer conservative management:
| Symptom relief |
|
| Diet changes |
|
| Lifestyle advise |
|
Do not offer antibiotics to manage diverticular disease.
Complications
Key complication is the development of acute diverticulitis.
Acute Diverticulitis
Clinical Features
Acute onset of:
- Left iliac fossa abdominal pain
- Rectal bleeding / passage of mucus
- Sudden change in bowel habit
- Nausea and vomiting
- Fever
The presence of an abdominal mass / perirectal fullness on DRE suggests a possible diverticular abscess.
Investigation and Diagnosis
Blood Tests
Standard workup:
- FBC
- U&E
- CRP
Blood test findings that support the diagnosis of acute diverticulitis:
- Leukocytosis
- ↑ CRP
If white blood cells and CRP are not raised, acute diverticulitis is very unlikely. Diverticular disease or alternative diagnoses should be considered.
Imaging
1st line: contrast CT abdomen-pelvis
- Supportive findings
- Colonic wall thickening
- Pericolic fat stranding
- Inflamed diverticula
2nd line:
- Ultrasound
- Non-contrast CT
- MRI
Colonoscopy should be avoided during acute diverticulitis due to the risk of perforation and is typically deferred until 6–8 weeks after resolution of symptoms
Complications
Key complications of acute diverticulitis: [Ref]
- Diverticular abscess
- Bowel perforation and peritonitis
- Bowel obstruction (from acute swelling / abscess compression / colonic strictures)
- Fistula formation
- Colovesical fistula: recurrent UTIs, pneumaturia (air in urine), faecaluria (faeces in urine)
- Colovaginal fistula: copious vaginal discharge, passage of stool or flatus via the vagina, recurrent vaginal infections
- Diagnosis: CT
- Management: surgery
Management
Uncomplicated Acute Diverticulitis
Uncomplicated acute diverticulitis can be managed as an outpatient
Typical management:
- Paracetamol for analgesia
- Oral antibiotics (no antibiotics can be considered if the patient is systemically well)
- 1st line: co-amoxiclav for 5 days
- 2nd line: metronidazole + cefalexin or trimethoprim or ciprofloxacin
- Bowel rest (clear liquid diet until improvement of symptoms)
The MHRA statement on fluoroquinolones (updated in Jan 2024) emphasises that fluoroquinolone antibiotics must only be prescribed when other commonly recommended antibiotics are inappropriate.
This restriction follows concerns over serious, disabling, long-lasting, and potentially irreversible side effects, including:
- MSK: tendonitis, tendon rupture (Achilles tendon rupture is classic), muscle pain and weakness, joint pain
- Neuro: peripheral neuropathy, altered taste / smell / hearing
- Mental health: depression, anxiety, panic attacks, memory impairment
- Psych: confusion, suicidal thoughts / attempts
A notable exception is acute bacterial prostatitis, where fluoroquinolones (ciprofloxacin / ofloxacin) remain the 1st line antibiotics despite the safety issues.
Complicated Acute Diverticulitis
IV broad-spectrum antibiotics should be offered routinely
Example 1st line options:
- Co-amoxiclav
- Cefuroxime + metronidazole
- Amoxicillin + gentamicin + metronidazole
- Ciprofloxacin + metronidazole
Subsequent definitive management depends on the complication:
| Complication | Management |
|---|---|
| Diverticular abscess | If the abscess is >3 cm, consider:
|
| Bowel perforation | Offer surgery |
Choice of surgery:
- Bowel resection with primary anastomosis +/- diverting stoma (temporary loop ileostomy) – for stable patients
- Hartmann’s procedure (sigmoid colectomy + end colostomy + rectal stump closure) – for unstable / high-risk patients or those with faecal peritonitis
If a complicated diverticulitis progresses to bowel perforation with diffuse peritonitis, sepsis, or haemodynamic instability, an urgent exploratory laparotomy via a midline incision is required.
See the Gastrointestinal (GI) Perforation article for more details.