Routine colonoscopy following acute uncomplicated diverticulitis

Sir,

Thank you for your request for further clarification of aspects of this study. Our study found that in patients who have had acute uncomplicated diverticulitis, having colonoscopy the yield of advanced colonic neoplasia is equivalent to or less than that detected on screening asymptomatic average-risk individuals. These results question the value of routine colonoscopy after an episode of acute uncomplicated diverticulitis. These results are in contrast to the recently published ACPGBI position Statement on elective resection for diverticulitis which states that “Barium enema or colonoscopy after resolution of the acute episode is essential to rule out alternative diagnosis or second pathologies” (1).

Aravinda Page et al report similar results to ours in a smaller series in their letter however they appear to have included some patients with complicated diverticular disease requiring percutaneous drainage. In our study complicated diverticulitis was deliberately excluded as this is more difficult to differentiate from neoplasia on CT. This is one of a number of important differences between this study and a recent study published by Lau et al (2). Lau’s study found a neoplasia rate of 2.1% in patients after a CT “suggesting” acute diverticulitis. Complicated cases were included and these cases were associated with a much higher risk of neoplasia on subsequent colonoscopy compared with uncomplicated cases (Odds ratios 6.7, 4 and 18 for abscess, perforation and fistula respectively). These results in fact support the findings of the present study and vindicate the exclusion of complicated diverticulitis.

H Colvin et al in their letter ask three questions; firstly what were the indications for and timing of colonoscopy patients? In the published manuscript we state that “of the 292 patients included in the study 205 patients (70.2 per cent) underwent subsequent evaluation of their colon or had undergone colonoscopy/CTC within the preceding 2 years”. The indications of those who had colonoscopy prior to the episode of acute diverticulitis was not looked at, in the case of those who had their colonic assessment after, it was the index episode of acute uncomplicated diverticulitis that lead to this evaluation. Colonoscopies within two years of the index episode of diverticulitis were included in our study as it is common practice not to reinvestigate the colon in patients admitted with a diagnosis of diverticulitis and recent luminal imaging. While the colonic visualisation rate of 70.2% was high compared to other studies, the NZ cancer registry was cross checked to ensure no cancer cases had been missed in those patients where colonoscopy results were not available and no cancers were found in this group with a median follow up of 43 months.

H Colvin et al also ask why we used of a foreign population as a control group which may be criticised as there are inevitably demographic and management variations across such broad geography and go on to ask was there a reason why a sample from less far afield was not considered? I am not certain what they refer to here as the study was done in New Zealand (The UK is not the only place with a city called Christchurch). If they are referring to the discussion and reference to the meta analysis 68,324 participants have screening colonoscopies (3), then this meta analysis includes studies from many countries around the world.

And lastly they ask if the title of the paper is slightly misleading in that it should make clear that these cases of diverticulitis were diagnosed by computerised tomography in the first instance. In keeping with the ACGBI guidelines we believe “patients should not be told that they have diverticulitis unless there is colonoscopic and/or radiological evidence of inflammation in the presence of diverticular disease.” (1)

The authors of the present study stress in the methods, discussion and conclusion that the paper is dealing with CT diagnosed diverticulitis, the current gold standard for diagnosis. We point out that the need for follow-up luminal imaging in those with only a clinical diagnosis of diverticulitis, complicated diverticulitis or those with other factors independently warranting colonoscopy should be considered separately. The findings of the present study should obviously only be applied to those with a CT diagnosis of uncomplicated acute diverticulitis performed on modern CT scanners and reported by radiologists experienced in gastrointestinal imaging.

Yours sincerely

Westwood DA, Eglinton TW, Frizelle FA.
Colorectal Unit, Department of Surgery, Christchurch Hospital,
Christchurch , New Zealand
Frank.Frizelle@cdhb.govt.nz

References

1. Fozard JB, Armitage NC, Schofield JB, Jones OM; Association of Coloproctology of Great Britain and Ireland. ACPGBI position statement on elective resection for diverticulitis. Colorectal Dis. 2011 Apr;13 Suppl 3:1-11.

2. Lau KC, Spilsbury K, Farooque Y, Kariyawasam SB, Owen RG, Wallace MH, Makin GB. Is colonoscopy still mandatory after a CT diagnosis of left-sided diverticulitis: can colorectal cancer be confidently excluded? Dis Colon Rectum. 2011;54(10);1265-70.

3. Niv Y, Hazazi R, Levi Z, Fraser G. Screening colonoscopy for colorectal cancer in asymptomatic people: a meta-analysis. Dig Dis Sci 2008; 53: 3049-54.

• Commentor: Westwood DA, Eglinton TW, Frizelle FA. - Christchurch Hospital, New Zealand
• Date: Oct 27, 2011

Sir,

Westwood and colleagues raise important questions regarding colonic visualisation following a computerised tomography diagnosis of simple acute diverticulitis. However there are a number of areas that we would feel are worthy of further discussion.

Firstly, indications for and timing of colonoscopy should be clarified. The inclusion of patients undergoing colonoscopy prior to the computerised tomography diagnosis could lead to selection bias. There may also be patients who underwent colonoscopy up to five years post acute diverticulitis and interval carcinoma may result [1]. The numbers of neoplasms detected was low but we would suggest that the timescale be clarified as this may be an important factor in any chance in practice advocated by this and similar studies.

The use of a foreign population as a control group may be criticised as there are inevitably demographic and management variations across such broad geography. Was there a reason why a sample from less far afield was not considered?

We would humbly suggest that the title of the paper is slightly misleading in that it should make clear that these cases of diverticulitis were diagnosed by computerised tomography in the first instance.

We would appreciate the above clarification and would be interested to hear the authors’ response in the context of published data suggesting contrary conclusions [2].

Yours sincerely,

HS Colvin, R Velineni, AGNR Robertson, S Yalamarthi, PJ Driscoll
Queen Margaret Hospital, Fife
hcolvin@doctors.net.uk

References

1. Farrar WD, Sawhney MS, Nelson DB, Lederle FA, Bond JH. Colorectal cancers found after a complete colonoscopy. Clin Gastroenterol Hepatol. 2006;4(10):1259-64.

2. Lau KC, Spilsbury K, Farooque Y, Kariyawasam SB, Owen RG, Wallace MH, Makin GB. Is colonoscopy still mandatory after a CT diagnosis of left-sided diverticulitis: can colorectal cancer be confidently excluded? Dis Colon Rectum. 2001;54(10);1265-70.

• Commentor: HS Colvin, R Velineni, AGNR Robertson, S Yalamarthi, PJ Driscoll - Queen Margaret Hospital
• Date: Oct 17, 2011

Sir,

We commend Westwood and colleagues on their single-centre retrospective longitudinal study investigating the validity of routine luminal imaging following hospital admission with acute uncomplicated diverticulitis based on computed tomography (CT) diagnosis.

Their conclusions suggesting that subsequent colonic evaluation following acute uncomplicated diverticulitis may not be required are echoed in our own local experience. We carried out a similar study for the year 2009 to quantify the added diagnostic value of luminal imaging in uncomplicated acute diverticulitis treated with antibiotics and radiologically guided abscess drainage if required. We excluded all patients requiring surgery during their admission. Ninety-six patients were included, with follow-up endoscopy arranged for 80 and an attendance of 76% achieved. No cases of colorectal cancer were identified, including in those who did not have endoscopy. Adenomas were found in 6 patients (8%), with only one having high grade dysplasia.

Our findings support those of Westwood et al, and add further to their proposal that in the absence of other factors, follow-up luminal imaging may not be required after CT proven diverticulitis that is treated without surgery.

A Aravinda Page, A Khan, R Justin Davies
Cambridge Colorectal Unit, Addenbrookes Hospital
Cambridge University Hospitals NHS Foundation Trust
aravindapage@gmail.com

• Commentor: A Aravinda Page, A Khan, R Justin Davies - Cambridge Colorectal Unit, Addenbrookes Hospital
• Date: Oct 05, 2011