Key Facts

Diverticular disease is one of the most common conditions of the large intestine in Western populations. The vast majority of people with diverticula remain asymptomatic (diverticulosis). A minority develop symptomatic disease or complications.

Epidemiology

Prevalence increases with age: <5% under 40, ~30% aged 40-60, >50% over 70. Equal sex distribution. Western populations have much higher prevalence than African and Asian populations (attributed to low-fibre diet). Complications requiring hospitalisation are increasing.

Aetiology

• Low-fibre diet: most important modifiable risk factor — reduces stool bulk, increases colonic transit time and intraluminal pressure
• Age: progressive weakening of colonic wall, loss of elastin
• Connective tissue disorders: Ehlers-Danlos, Marfan (diverticulosis at younger age)
• Medications: NSAIDs, corticosteroids, opioids (increase complication risk)

Pathophysiology

Diverticula are false (pulsion) diverticula — herniation of mucosa and submucosa through the muscular layer at points of weakness where the vasa recta penetrate the circular muscle. Increased intraluminal pressure (from low-fibre diet, colonic dysmotility) drives herniation. Diverticulitis occurs when a diverticulum becomes obstructed (faecalith) → bacterial proliferation → micro-perforation → pericolic inflammation/abscess. The proximity of vasa recta to diverticula explains the propensity for significant haemorrhage.

Symptomatic Diverticular Disease

• Intermittent LIF pain ("left-sided appendicitis")
• Altered bowel habit (constipation or diarrhoea)
• Bloating
• Often overlaps with IBS symptoms

Acute Diverticulitis (see separate entry)

• Constant LIF pain, fever, nausea
• LIF tenderness ± guarding

Diverticular Bleeding

• Sudden painless massive PR bleeding (maroon/bright red)
• Usually self-limiting (80%)
• Can cause haemodynamic instability if severe

Red Flags

• Peritonism (rigid abdomen — perforation)
• Pneumaturia/faecaluria (colovesical fistula)
• Large bowel obstruction symptoms (absolute constipation, distension, vomiting)
• Massive PR bleeding with haemodynamic instability

Bedside

• Observations: pulse, BP, temperature
• Abdominal examination: LIF tenderness, guarding, mass
• DRE: PR bleeding assessment

Bloods

• FBC: WCC (infection), Hb (bleeding)
• CRP: raised in diverticulitis
• U&Es, LFTs: baseline
• Lactate: if concern for ischaemia/sepsis
• Group and save/crossmatch: if significant bleeding

Imaging

• CT abdomen/pelvis with contrast: gold standard for acute diverticulitis — pericolic fat stranding, wall thickening, abscess, perforation
• Hinchey classification (CT-based staging of diverticulitis complications): I (pericolic abscess), II (pelvic/distant abscess), III (purulent peritonitis), IV (faecal peritonitis)
• Colonoscopy: NOT in acute phase (perforation risk); perform 6-8 weeks after acute episode to exclude malignancy
• CT colonography: alternative for excluding malignancy post-episode

Special Tests

• CT angiography/mesenteric angiography: for active diverticular bleeding if not self-limiting
• Capsule endoscopy: rarely needed; if diagnostic uncertainty

Non-pharmacological

• Asymptomatic diverticulosis: reassurance; high-fibre diet (30 g/day), adequate hydration, regular exercise
• Symptomatic diverticular disease: high-fibre diet (introduce gradually to minimise bloating), weight management

Pharmacological

• Symptomatic disease: bulk-forming laxatives (ispaghula husk) if constipation; antispasmodics (mebeverine) for pain
• Acute diverticulitis: see separate entry
• Diverticular bleeding: resuscitation (IV fluids, blood products), usually conservative; tranexamic acid 1 g IV if severe

Surgical/Interventional

• Diverticular bleeding: colonoscopic haemostasis (clipping, injection), mesenteric angiography + embolisation if ongoing, emergency colectomy if life-threatening
• Recurrent diverticulitis/complications: elective sigmoid colectomy (laparoscopic preferred); after 2+ episodes of uncomplicated diverticulitis or after 1 complicated episode
• Colovesical fistula: sigmoid colectomy with fistula repair
• Abscess drainage: percutaneous CT-guided drainage for Hinchey I-II abscesses ≥3 cm

Referral Criteria

• Surgical referral for complicated/recurrent diverticulitis
• Colonoscopy 6-8 weeks post-acute episode to exclude malignancy (especially first episode)
• Emergency surgical review for perforation/peritonitis

Most people with diverticulosis remain asymptomatic. ~20% develop symptomatic diverticular disease. ~4% of those with diverticulosis develop diverticulitis. After one episode of uncomplicated diverticulitis, recurrence rate is ~20-30% over 10 years. Complicated diverticulitis (abscess, perforation) carries higher morbidity and mortality. Diverticular bleeding is self-limiting in ~80% but recurrence rate is ~25%. Emergency surgery for perforation (Hinchey III-IV) carries mortality of 10-20%.

Hinchey Classification

Diverticular Bleeding vs Other Lower GI Bleed Causes