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Diverticulosis is the formation of abnormal pouches in the bowel wall, while diverticulitis is inflammation or infection of these pouches. These conditions are known as diverticular disease. Diverticulosis commonly starts presenting at around age 40 and increases as you get older. Approximately 50% people >70 years have it.


  • Sharp abdominal pain, often LIF (70%) – most diverticula occur in sigmoid colon
  • Fever
  • Abdo distension/bloating/flatulence
  • Change in bowel habits – constipation/diarrhoea
  • Nausea/vomiting
  • Patient may have known diverticular disease.


  • Abscess
  • Obstruction
  • Perforation
  • Peritonitis
  • Haemorrhage
  • Fistula.


  • Simple diverticulitis, localised abdominal tenderness in the area of the affected diverticula and fever
  • Right lower quadrant tenderness, mimicking acute appendicitis, can occur in right-sided diverticulitis
  • Abscess formation - tender palpable mass
  • Peritonitis - generalised tenderness with rebound and guarding, abdomen may be distended and tympanic to percussion, bowel sounds can be diminished or absent
  • Fistula - women with a colovaginal fistula may present with a purulent vaginal discharge, colovesical fistula may present as urinary tract symptoms
  • PR should be performed
  • Elderly patients and some patients taking corticosteroids may have unremarkable findings, even in the presence of severe diverticulitis.


  • WBC - may show leukocytosis and a left shift, but may be normal in 20-40% of patients especially immunocompromised or elderly
  • Hb - important in patients who report hematochezia
  • Electrolytes - helpful if dehydrated/vomiting/diarrhoea
  • Cr – helpful prior to CT contrast
  • LFT and lipase - rule out other causes abdominal pain
  • BHCG - any female of child-bearing age with abdominal pain
  • Consider CRP – has been found to help differentiate severity of disease – CRP>150 suggests complicated disease and CT should be carried out (Makela, JT et al.)
  • UA +/- MC&S
  • Blood cultures should be obtained prior to the administration of empiric parenteral antimicrobial therapy in patients who are severely ill or in those with complicated disease


  • CT abdomen considered the best imaging method to confirm the diagnosis. Sensitivity and specificity, especially with helical CT and colonic contrast, can be as high as 97%. Possible CT findings include the following:
    • Pericolic fat stranding due to inflammation
    • Colonic diverticula
    • Bowel wall thickening
    • Soft-tissue inflammatory masses
    • Phlegmon
    • Abscess.
  • Others to consider:
    • Xray – has little value in this situation
    • Contrast enema – replaced by CT, risk perforation
    • USS – good but operator dependent and not useful for surgical planning
    • MRI – to be increasingly utilised, good sensitivity and specificity, no radiation, can pick up alternate diagnosis.
  • Colonoscopy.


Clinical staging by Hinchey's classification is geared toward choosing the proper surgical procedure when diverticulitis is complicated, as follows:

  • Stage I: Diverticulitis with phlegmon or localised pericolic or mesenteric abscess.
  • Stage II: Diverticulitis with walled-off pelvic, intra-abdominal, or retroperitoneal abscess.
  • Stage III: Perforated diverticulitis causing generalised purulent peritonitis.
  • Stage IV: Rupture of diverticula into the peritoneal cavity with fecal contamination causing generalised fecal peritonitis.


Patients with mild diverticulitis – mild abdominal pain without signs systemic infection, typically with Hinchey’s stage I disease, can be treated with the following outpatient regimen:

  • A clear liquid diet
  • Patients can advance the diet slowly as tolerated after clinical improvement occurs, which should be within 48-72 hours
  • Simple oral analgesia e.g. paracetamol
  • Recent trials (see references) have suggested that antibiotic therapy for acute, uncomplicated diverticulitis may not be required for patients with mild abdominal pain and tenderness who do not have significant systemic signs or symptoms – i.e. patients in these trials had raised inflammatory markers and fever and confirmed diagnosis of diverticulitis on CT.
  • Patients who have outpatient treatment need to have good follow up including GP review in 48-72 hours.

Indications for hospital admission and antibiotic treatment include the following:

  • Systemic signs of infection or peritonitis
  • Inability to tolerate oral hydration
  • Failure of outpatient therapy - persistent or increasing fever, pain, or leukocytosis after 2-3 days
  • Immunocompromised or significant comorbidities or elderly
  • Pain severe enough to require parenteral narcotic analgesia.

Inpatient treatment is as follows:

  • Bowel rest and IV fluids
  • Broad-spectrum intravenous antibiotic coverage until culture results available – use local antibiotic guidelines
    • Gentamicin 5mg/kg IV then adjust according to renal function
    • Plus Amox/Ampicillin 2g IV 6 hourly
    • Plus Metronidazole 500mg IV 12 hourly.
  • Pain relief eg IV morphine. NSAIDs should be avoided if possible as have been shown to increase risk perforation.
  • CT–guided percutaneous drainage is indicated for peridiverticular abscesses >4 cm in diameter

Surgical indications

Usually for Hinchey’s stage III or IV disease:

  • Free-air perforation with faecal peritonitis
  • Suppurative peritonitis secondary to a ruptured abscess
  • Uncontrolled sepsis
  • Abdominal or pelvic abscess (unless CT-guided aspiration possible)
  • Fistula formation
  • Inability to rule out carcinoma
  • Intestinal obstruction
  • Failing medical therapy
  • Immunocompromised status
  • Extremes of age.

Further References and Resources

  1. Biondo, S. et al. (2014) Outpatient versus hospitalisation management for uncomplicated diverticulitis: a prospective, multicenter randomised clinical trial (DIVER Trial)Annals of Surgery, January 2014, vol. 259, no. 1, pp. 38-44.
  2. Chabok, A. et al. (2012) Randomised clinical trial of antibiotics in acute uncomplicated diverticulitisBritish Journal of Surgery, April 2012, vol. 99, no. 4, pp. 532-539.
  3. Isacson, D. et al. (2015) Outpatient, non-antibiotic management in acute uncomplicated diverticulitis: a prospective studyInternational Journal of Colorectal Disease, Epub ahead of print.
  4. Makela, J.T. et al. (2015) The role of CRP in prediction of the severity of acute diverticulitis in an emergency unitScandanavian Journal of Gastroenterology, vol. 50, no. 5, pp. 536-541.
  5. Shahedi, K. et al. (2015) DiverticulitisMedscape
  6. NICE guidelines - Diverticulitis implications for practice
  7. eTG Therapeutic Guidelines, Diverticulitis

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