Colonoscopy after CT-diagnosed acute diverticulitis: Is it really necessary?

It is estimated that up to 20%–25% of patients with colonic diverticula will progress to diverticulitis.1,2 The diagnosis of acute diverticulitis is typically made using a combination of history, clinical exam, biochemical investigations and diagnostic imaging. Computed tomography (CT) has emerged as the imaging modality of choice given its high sensitivity and specificity for the diagnosis of diverticulitis, with some studies reporting up to 100% in either measure.3–8 Computed tomography findings of diverticula, inflammation of pericolic fat, bowel wall thickness greater than 4 mm and/or pericolic fluid/abscess are highly suggestive of acute diverticulitis.1,8,9 A CT scan also provides prognostic information and guides management by determining whether the diverticulitis is complicated by abscess, fistula formation, stricture/obstruction or free rupture. While most cases of uncomplicated diverticulitis respond well to conservative treatment, complicated diverticulitis requires surgical intervention. There is overlap in the findings of acute diverticulitis and colorectal cancer (CRC), and CT findings alone are insufficient to exclude malignancy approximately 10% of the time.1,10 As a result, the American Society of Colon and Rectal Surgeons recommend performing a colonoscopy to exclude a potential malignancy after an episode of acute diverticulitis has resolved.1,9,11 However, since the advent of multidetector CT scanners that are capable of capturing images more quickly and thus reduce motion artifacts, the image qualities and diagnostic accuracy of CT scans have improved substantially. With increased resolution of the newer 64-slice CT scans that are currently in widespread use, acute diverticulitis can be diagnosed more accurately,12,13 and it may be possible to adequately distinguish acute diverticulitis from malignancy based on radiological features alone. Routine follow-up colonoscopy may no longer be required in patients with acute diverticulitis. The primary aim of this study was to determine the prevalence of colon cancer in patients with diverticulitis diagnosed on high-resolution CT scan to determine the need for follow-up colonoscopy in this patient population.