investigations in acute diverticulitis

Last edited 03/2021 and last reviewed 06/2021

Investigation of suspected acute diverticulitis


Primary care


For people with suspected uncomplicated acute diverticulitis who are not referred for same-day hospital assessment:

  • reassess in primary care if their symptoms persist or worsen and
  • consider referral to secondary care for further assessment

Secondary care (1)

For people with suspected complicated acute diverticulitis who have been referred for same-day hospital assessment, offer a full blood count, urea and
electrolytes test and C-reactive protein test.


If the person with suspected complicated acute diverticulitis has raised inflammatory markers, offer a contrast CT scan within 24 hours of hospital
admission to confirm diagnosis and help plan management. If contrast CT is contraindicated, perform one of the following:

  • a non-contrast CT or
  • an MRI or
  • an ultrasound scan, depending on local expertise

If inflammatory markers are not raised, think about the possibility of alternative diagnoses.

A review suggests (2):

  • in patients presenting with suspected acute diverticulitis
    • an abdominal computed tomography scan should be performed to confirm the diagnosis, to determine the severity of disease, and to rule out an alternative diagnosis
    • is most important for the first presentation and less important for a stereotypical mild recurrence
  • in centers with expertise in ultrasonography
    • a step-up approach with computed tomography performed after an inconclusive or negative ultrasound scan may be considered
    • computed tomography
      • performs better in obese patients and is better able to assess the distal sigmoid colon, which is difficult to visualize with transabdominal ultrasonography
  • colonoscopy
    • should be performed six to eight weeks after a diagnosis of complicated diverticulitis or first episode of uncomplicated diverticulitis
    • in the absence of alarm symptoms, a colonoscopy does not need to be repeated if a high quality examination has been performed in the previous year
    • patients with recurrent uncomplicated diverticulitis and no alarm symptoms should follow routine colorectal cancer screening and surveillance intervals
  • ongoing gastrointestinal symptoms
    • common after recovery from the acute phase of diverticulitis, and alternative diagnoses should be considered
    • repeat imaging and colonoscopy is often necessary to rule out a misdiagnosis or ongoing inflammation

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