Diagnosis of DD
Radiology
Barium enema was once considered the best tool for demonstrating the extent and severity of colonic DD. This is because this radiological technique allows examination of the entire colon, including all anatomical alteration (e.g. stenosis) that may affect endoscopic exploration. However, the use of BE is now discouraged due to poor patient compliance, long examination time, high risk of complications and radiation exposure. There are now more sophisticated and sensitive methods that provide greater information about the characteristics of the colonic wall and the pericolonic tissues. The diagnostic accuracy of barium enema for DD is similar to that of computer tomograpy colonography (CTC), but use of barium enema should only be considered if CTC is unavailable. CTC is easy, standardised and much less labour-intensive and invasive than barium enema or colonoscopy (Figure 1). CTC can provide a balanced view of the disease by incorporating visual analysis with quantitative analysis by using a CTC-based DD severity score; this score appears to correlate with relevant coexisting lesions and can potentially influence therapeutic decision making. CTC is strongly advisable in cases where colonoscopy is incomplete, has failed, or is unfeasible, but is contraindicated in acute abdominal conditions, such as acute diverticulitis, because of the high risk of complications (i.e. perforations).
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Figure 1.
Colonic diverticulosis on CT colonography. This technique is strongly advised when colonoscopy is incomplete, failed, or unfeasible.
Abdominal computed tomography (CT) plays an important role in the diagnosis of diverticulosis, but it is particularly helpful in diagnosing acute diverticulitis. Moreover, a CT scan is able to differentiate between uncomplicated (acute diverticular inflammation without stenoses, and/or fistulas and/or abscesses) (Figure 2a) and complicated diverticulitis (acute diverticular inflammation with stenoses, and/or fistulas and/or abscesses) (Figure 2b).
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Figure 2.
Acute diverticulitis on computerised tomography. (a) Uncomplicated disease. Thickening of the colonic wall with fat stranding in pericolic tissue (arrow). (b) Complicated disease. Thickening of the colonic wall with the presence of an abscess (arrow).
Ultrasound has also been successfully used for diagnosis, and magnetic resonance imaging has significant potential as a radiation-free imaging test for acute colonic diverticulitis. However, results from these imaging modalities remain inconclusive in terms of their ability to provide clinical direction.
Colonoscopy
Colonoscopy remains the main tool used for the diagnosis and management of diverticulosis and DD. Diverticulosis is the most commonly reported finding on routine colonoscopy. Endoscopic diagnosis of diverticulosis is generally incidental and does not affect the safety or accuracy of colonoscopy. However, detection of massive diverticulosis, especially in the sigmoid, may increase the risk of perforation, because of rigidity of the colon and potential confusion between diverticular lumen and true colonic lumen when multiple large diverticular openings are detected. Colonoscopy is also able to detect the first occurrence of acute diverticulitis. Ghorai et al. found that endoscopic findings of diverticular inflammation were reported in about 0.8% of patients undergoing colonoscopy without clinical evidence of diverticulitis. More recently, Tursi et al. found that endoscopic signs of diverticulitis may be detected in 2% of people undergoing colonoscopy.
Colonoscopy is currently advised in managing DD of the colon, ranging from treatment to diverticular bleeding to differential diagnosis with IBDs or colorectal cancer (Figure 3).
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Figure 3.
Endoscopic appearances of inflammation in association with diverticula. (a) Inflammation affects only the diverticulum (indicated by the arrow). This is diverticulitis. (b) Inflammation affects the entire colonic mucosa. This is ulcerative colitis in a patient with diverticulosis (diverticulum indicated by the arrow). (c) Inflammation affects only inter-diverticular mucosa, with sparing of the diverticulum (indicated by the arrow). This is segmental colitis associated with diverticulosis (SCAD).