Practice Rational Imaging

Suspected left sided diverticulitis

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f928 (Published 27 February 2013) Cite this as: BMJ 2013;346:f928
  1. N de Korte, consultant surgeon1,
  2. W de Monyé, consultant radiologist2,
  3. H B A C Stockmann, consultant surgeon3
  1. 1Department of Surgery, Spaarne Ziekenhuis, Hoofddorp, Spaarnepoort 1, 2134 TM Hoofddorp, Netherlands
  2. 2Department of Radiology, Kennemer Gasthuis, Haarlem, Netherlands
  3. 3Department of Surgery, Kennemer Gasthuis, Haarlem, Netherlands
  1. Correspondence to: N de Korte ndekorte{at}yahoo.com

de Korte and colleagues make the case for using ultrasonography as the first investigation to confirm the diagnosis in patients with suspected diverticulitis

Learning points

  • Left sided diverticulitis can be accurately diagnosed by clinical findings and laboratory tests in only a few patients so imaging tests are usually necessary to confirm the diagnosis

  • Computed tomography and ultrasonography have similar diagnostic accuracy for uncomplicated diverticulitis, but as ultrasonography is widely available, cheap, and avoids exposure to radiation. When possible it should be the first choice of imaging to confirm the diagnosis

  • In the case of non-diagnostic or inconclusive results on ultrasonography, computed tomography should be performed as it is superior to ultrasonography in identifying an alternative diagnosis

  • In a critically ill patient, with a clear indication of infection or high fever, computed tomography should be done without delay to rule out complicated (abscess, perforation) diverticulitis and to guide treatment

A 55 year old man presented to the emergency department with a two day history of progressive pain in the left lower quadrant. On physical examination he had a temperature of 38°C and marked tenderness in the left lower quadrant and some tenderness in the suprapubic area. No rebound tenderness was present. Laboratory testing showed a C reactive protein concentration of 25 mg/L and a white cell count of 13.8 ×109/L.

What is the next investigation?

This patient is suspected of having a left sided diverticulitis. Diagnosis based solely on clinical and laboratory parameters is imperfect. The sensitivity for diagnosing acute diverticulitis on clinical grounds alone is only 68%.1 A small subset of patients with pain only in the lower left quadrant, raised concentration of C reactive protein, and the absence of vomiting has recently been identified in which diverticulitis can be identified with a high degree of diagnostic accuracy without additional imaging.2 3 These results, however, should be validated in a prospective cohort. In most patients with suspected diverticulitis additional imaging is required to confirm the diagnosis.

Ultrasonography—The use of ultrasonography as a first line investigation for diverticular disease is controversial, and most guidelines advocate the use of computed tomography.4 5 6 Some studies, however, have shown that graded compression ultrasonography has a diagnostic accuracy for diverticulitis of up to 92% sensitivity and 90% specificity. In graded compression ultrasonography interposing fat and bowel can be displaced or gradually compressed to show underlying structures. If the bowel cannot be compressed, the non-compressibility itself is an indication of inflammation.7 Ultrasonography is widely available, cheap, and avoids exposure to radiation. It does, however, have major limitations, such as operator dependency, limited experience and availability in some countries, and limitations in obese patients, which is probably why it is not yet widely used as the first investigation. Ultrasonography can also be less accurate in identifying the complications associated with diverticular disease, such as small abscesses, deep pelvic abscesses, and small amounts of free air, although the only available evidence shows that it is as good as computed tomography in identifying abscesses in diverticulitis. Only one small study prospectively compared computed tomography and ultrasonography in diverticulitis and found good agreement between the two techniques for abscesses (κ=0.69).8

Computed tomography—Computed tomography has slightly higher diagnostic accuracy than ultrasonography (sensitivity 94%, specificity 99%), though in a recent meta-analysis this was not significant.7 It is superior to ultrasonography for alternative diagnoses, with a sensitivity between 50% and 100% compared with a sensitivity of 33% and 78% for ultrasonography.7 Furthermore, it is more useful in the planning of percutaneous drainage of an abscess or surgery.7 The main drawback of computed tomography is the exposure to radiation. The newest generation scanners that use advanced reconstruction algorithms, however, can reduce the dose by up to 50%. Moreover, low dose unenhanced computed tomography offers equal diagnostic accuracy compared with normal dose scanning with oral or intravenous contrast.9

Computed tomography and ultrasonography—The prospective OPTIMA study compared the two techniques head to head in 1021 patients with acute abdominal pain and provided the highest level of evidence for a diagnostic accuracy study. A strategy of ultrasonography first and computed tomography only in those with inconclusive or negative results resulted in the best sensitivity and lowest exposure to radiation.10 11

We believe that, if the skills and technology are available, ultrasonography can be used confirm the diagnosis in a patient with suspected acute uncomplicated diverticulitis. This is based on the highest level of evidence available and contradicts most (older) guidelines. This is the case in most patients presenting with acute diverticulitis.12 Computed tomography should be carried out in a critically ill patient with a clear indication of infection (raised C reactive protein concentration, raised white cell count) or high fever in whom complicated diverticulitis (abscess or perforation) is suspected or in a patient with inconclusive or negative results on ultrasonography.10 11

Magnetic resonance imaging—Magnetic resonance imaging could combine the advantages of computed tomography without the exposure to radiation. Reported sensitivity rates vary between 86% and 100% and specificity rates between 88% and 100%.13 Limited availability, high costs, length of the examination, and limited experience hamper the current use of magnetic resonance imaging in the diagnosis of diverticulitis.

Outcome

Ultrasonography showed thickening of the sigmoid bowel wall and inflammation of the pericolic fat around a diverticulum consistent with sigmoid diverticulitis (fig 1). The patient was admitted to hospital for bowel rest and given intravenous antibiotics, although the use of antibiotics in uncomplicated diverticulitis is disputed.14 15 After two days there was a distinct rise in temperature to 39°C. Because complicated diverticulitis was suspected, computed tomography was performed and showed a pericolic abscess consistent with Hinchey Ib (table) diverticulitis (fig 2). Diverticulitis with pericolic abscess formation is generally treated with antibiotics alone.16 In this patient antibiotic treatment was continued, the fever subsided, and infection parameters declined. He was followed up at the outpatient clinic with continuation of oral antibiotic treatment for 10 days. Four weeks after the initial presentation, results of laboratory tests were normal, he was free from pain, and there were no problems with defecation.

Figure1

Fig 1 Graded compression ultrasound image showing compressed sigmoid colon loop (star) with diverticulum (small arrow) with inflamed pericolic fat (large arrow). Ultrasound transducer is marked with circle

Figure2

Fig 2 Computed tomogram showing loop of sigmoid colon (star) with pericolic abscess with fluid (small arrow) and air (large arrow). Inflamed pericolic fat is marked with circle

Modified Hinchey classification of acute sigmoid diverticulitis

View this table:

Notes

Cite this as: BMJ 2013;346:f928

Footnotes

  • This series provides an update on the best use of different imaging methods for common or important clinical presentations. The series advisers are Fergus Gleeson, consultant radiologist, Churchill Hospital, Oxford, and Kamini Patel, consultant radiologist, Homerton University Hospital, London. To suggest a topic for this series, please email us at practice{at}bmj.com.

  • Contributors: NdK drafted the manuscript. WdM assessed the images. All authors critically reviewed the manuscript and accepted the final version and are guarantors.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Provenance: Commissioned; externally peer reviewed.

References