title: Is colonoscopy still mandatory after a CT diagnosis of left-sided diverticulitis: can colorectal cancer be confidently excluded?
abstract: BACKGROUND
  It is routine practice to perform colonoscopy as a follow-up after an attack of diverticulitis, with the main aim to exclude any underlying malignancy.
  
  
  OBJECTIVE
  This study aimed to determine whether colonoscopy is necessary and what additional information is gained from this procedure.
  
  
  METHODS
  This is a study of a retrospective cohort.
  
  
  METHODS
  From January 2003 to June 2009, patients in whom left-sided diverticulitis was diagnosed on CT scan were matched with colonoscopy reports within 1 year from the date of CT by the use of radiology and endoscopy databases. Patients who had colonoscopy within 1 year before the CT scan were excluded. The Western Australian Cancer Registry was cross-referenced to identify patients who subsequently received diagnoses of cancers for whom colonoscopy reports were unavailable.
  
  
  METHODS
  The main outcome measures were the number of patients in whom colorectal cancers were diagnosed and other incidental findings, eg, polyps, colitis, and stricture.
  
  
  RESULTS
  Left-sided diverticulitis was diagnosed in 1088 patients on CT scan, whereas follow-up colonoscopy reports were available for 319 patients. Eighty-two (26%) patients had incidental findings of polyps (9 polyps >1 cm), and 9 patients (2.8%) received diagnoses of colorectal cancers on colonoscopy. After cross-referencing with the cancer registry, the overall prevalence of colorectal cancer among the cohort within 1 year of CT scan was 2.1% (23 cases). The odds of a diagnosis of colorectal cancer were 6.7 times (95% CI 2.4-18.7) in patients with an abscess reported on CT, 4 times (95% CI 1.1-14.9) in patients with local perforation, and 18 times (95% CI 5.1-63.7) in patients with fistula compared with patients with uncomplicated diverticulitis.
  
  
  CONCLUSIONS
  This study was limited by the unavailability of data for private/interstate hospitals, and the relatively small number of cancer cases reduced the statistical power of the study.
  
  
  CONCLUSIONS
  We recommend routine colonoscopy after an attack of presumed left-sided diverticulitis in patients who have not had recent colonic luminal evaluation. The rate of occult carcinoma is substantial in this patient population, in particular, when abscess, local perforation, and fistula are observed.
authors: Department of Surgery, Fremantle Hospital, Fremantle, Western Australia, Australia.
authors: K C
authors: KC
authors: Lau
authors: K
authors: K
authors: Spilsbury
authors: Y
authors: Y
authors: Farooque
authors: S B
authors: SB
authors: Kariyawasam
authors: R G
authors: RG
authors: Owen
authors: M H
authors: MH
authors: Wallace
authors: G B
authors: GB
authors: Makin
mesh_terms: D018784:Abdominal Abscess / Q000150:complications; D000293:Adolescent; D000328:Adult; D000368:Aged; D044683:Colon, Descending / Q000000981:diagnostic imaging*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D003937:Diagnosis, Differential; D004239:Diverticulitis, Colonic / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007412:Intestinal Fistula / Q000150:complications; D007416:Intestinal Perforation / Q000150:complications; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult