Diverticulitis is the infection of a diverticulum, an out-pouching of the intestinal mucosa. The presence of diverticula is called diverticulosis and if these cause symptoms then it is referred to as diverticular disease. Diverticula are thought to be due to increased intra-colonic pressure and usually occur along the weaker areas of the wall such as where the penetrating arteries enter the colonic wall; almost all diverticula are found in the sigmoid colon, although they may be found in the right colon in Asian patients. Diverticula are incredibly common and it is thought that 30% of Westerners will have diverticula by the age of 60. Only about 25% of people with diverticulosis will experience symptoms but 75% of these will experience an episode of diverticulitis.


  • Incidence: 250.00 cases per 100,000 person-years
  • Peak incidence: 70+ years
  • Sex ratio: 1:1
Condition Relative
Colorectal cancer0.26
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+


Risk factors
  • Age
  • Lack of dietary fibre
  • Obesity: especially in younger patients
  • Sedentary lifestyle
  • Smoking
  • NSAID use

Clinical features

Patients with diverticular disease typically present with a chronic history of:
  • Intermittent abdominal pain: particularly in the left lower quadrant
  • Bloating
  • Change in bowel habit: constipation or diarrhoea

Patients with acute diverticulitis typically present with an acute onset of:
  • Severe abdominal pain in the left lower quadrant: this may be in the right lower quadrant in some Asian patients
  • Nausea and vomiting (20-60%): this may be due to ileus or complicated diverticulitis with colonic obstruction
  • Change in bowel habit: constipation is more common (seen in 50%) but diarrhoea is also reported (25%)
  • Urinary frequency, urgency or dysuria (10-15%): this is due to irritation of the bladder by the inflamed bowel.
  • PR bleeding (in some cases).
  • Symptoms such as pneumaturia or faecaluria may suggest colovesical fistula while vaginal passage of faeces or flatus may suggest a colovaginal fistula.

  • Low grade pyrexia
  • Tachycardia
  • Tender LIF: in 20% there will be a tender palpable mass due to inflammation or an abscess
  • Possibly reduced bowel sounds
  • Guarding, rigidity and rebound tenderness may suggest complicated diverticulitis with perforation
  • Lack of improvement with treatment in seemingly uncomplicated diverticulitis may suggest the presence of an abscess.


  • FBC: raised WCC
  • CRP: raised
  • Erect CXR: may show pneumoperitoneum in cases of perforation
  • AXR: may show dilated bowel loops, obstruction or abscesses
  • CT: this is the best modality in suspected abscesses
  • Colonoscopy: should be avoided initially due to increased risk of perforation in diverticulitis


  • mild cases of acute diverticulitis may be managed with oral antibiotics, liquid diet and analgesia
  • if the symptoms don't settle within 72 hours, or the patient intiially presents with more severe symptoms, the patient should be admitted to hospital for IV antibiotics