1. When Is A Colonoscopy Not a Colonoscopy
Dr Linus Chang
Gastroenterologist

2. Mrs BP 67yo woman – referred for screening colonoscopy for +ve FOB
Index colonoscopy in Sep 2009
Multiple polyps; largest was resected (TVA)
Rebooked 8mo later for resection of remaining smaller polyps

3. Mrs BP – Colonoscopy 6mo later
Caecal ulcer
Failed to lift with submucosal injection of saline
Biopsied -> Carcinoma in situ

4. Caecal view Sep 2009
Caecal view May 2010

5. Mrs BP - Surgery Proceeded to R hemicolectomy
Early T2 CRC -> just infiltrating muscularis propria
Loss of nuclear staining seen for MLH1 and PMS2 (consistent with microsatellite instability)
0/10 lymph nodes involved
No adjuvant chemo recommended
Tumour was surrounded by flat lesions which were sessile serrated adenomas (SSA)

6. Colorectal Cancer 2nd most common cause of cancer death
Causes 9% of cancer death overall

7. Colonoscopy in screening for CRC
Screening colonoscopy in 1994 asymptomatic adults
5.7% had advanced neoplasms
Lieberman DA, et al N Engl J Med. 2000;343(3):162
Asymptomatic individuals (mean age 61) colonoscoped then followed for 8 years have reduced CRC incidence and death compared to expected incidence and SEERS data
Kahi CJ, et al. Clin Gas Hepat. 2009;7(7):770

8. Expected Adenoma Detection Rate
Age 30 50 70
> 1 adenoma or cancer
14.6% ( )
23.3%( )
35.2%( )
> 1 nonadenoma/noncancer
26%( )
27.6%( )
29.3%( )
Overall, in colonoscopies, 29.1% had at least 1 adenoma removed.
Males vs Females (24.5% vs 16.7%; p<0.0001)
Chen & Rex J Clin Gastro 2008; 42(6): ⏎

9. Risks of Colonoscopy 1 in 1000 of perforation or major bleeding
0.8/1000 if no biopsy
7/1000 if polypectomy or biopsy

10. Polyp detection depends on endoscopist
Risk of interval cancer between screening colonoscopy and repeat procedure depends on endoscopist’s adenoma detection rate
Withdrawal time of 6 minutes or more increases adenoma detection rate
Barclay RL, et al. N Engl J Med. 2006;355(24):2533

11. Less effective in R sided lesions?
Colonoscopy reduces deaths mainly from L sided CRC, but not R sided lesions:
Baxter NN, Ann Intern Med. 2009;150(1):1.
Singh H, Gastroenterology. 2010;139(4):1128
5% of CRCs arise as “interval” cancers following a colonoscopy

12. Sessile Serrated Adenomas
Distal polyps usually follow conventional adenoma-carcinoma sequence
Up to 20% of all CRCs may arise from serrated polyps
Only recognised as recently as 2003
Serrated pathway polyps become cancers with high levels of microsatellite instability (MSI)
Can become cancers more rapidly than conventional adenomas

13. This is what we’re missing!⏎

14. Sessile Serrated Adenomas (2)
SSAs represent 1-9% of all polyps
Present in 1-4% of the general population
Median age of patients 61
Trend toward female gender bias
More commonly in the proximal colon
Endoscopic appearance:
5mm or larger
Flat or depressed
Covered by adherent layer of yellowish mucus
In patients with at least one SSA
12% have LGD; 2% have HGD; 1% have adenocarcinoma
Huang CS, et al. Am J Gastro 2011; 106: ⏎

15. Natural History of SSAs
Lu F, et al. Am J of Surg Path 2010; 34(7):
All colonic polyps dx between studied
1402 hyperplastic polyps
81 polyps in 55 pts rediagnosed as SSA
40 SSA pts with no prev hx of CRC or AP-HGD
Of these, 5 developed CRC, 1 developed AP-HGD
CRC more commong in SSA pts than in controls with HP (12.5% vs 1.8%) and AP (12.5% vs 1.8%)
All subsequent CRC or AP-HGD developed in proximal colon
4 of 5 subsequent CRC showed MSI
Conclusion: 15% of SSA pts developed subsequent CRC or AP-HGD; especially in the R colon

16. Risk factors for developing SSAs
Cigarette smoking
Obesity
Female gender
Family history of CRC or polyps

17. How quickly to SSAs progress to cancer
We don’t know
Case study suggesting SSA-> CA in 8 months
Mrs BP

18. Surveillance post-resection
SSA with no dysplasia
5 years if <3 lesions, all <1cm in size
3 years if 3 or more, or any 1cm or more in size
SSA with dysplasia
3 years
Screening of first-degree relatives at age 40, or 10y prior to age of diagnosis

19. We are missing SSAs!
Mortality rates from R sided CRC not decreasing despite increasing use of screening colonoscopy
Interval cancers more likely to occur in proximal colon and demonstrate microsatellite instability suggesting they arise from SSAs
Adherent mucus coating is not a useful endoscopic sign unless prep is very good

20. Recognising SSAs Colonoscopy is the only reliable technique
Increasing recognition of SSA
6 min withdrawal time
Split dose bowel preparation
Advanced imaging techniques
Narrow Band Imaging
Indigo Carmine spray

21. Split dose Colonic Preparation
Traditional colonic preparation consists of solution given day prior to colonoscopy
Split dose prep involves giving for example, 2L of prep the day prior, and 1L on the morning of colonoscopy

22. Clear superiority of Split Dose Prep
Achieves better cleansing than conventional
Good/excellent views 75% vs 43% (p=.00001)
Best views within 8 hours of last fluid intake
Adenoma detection rates higher
24% vs 12%, (p=0.001)
Lower rates of failed caecal intubation
1% vs 11%; (p= )
Fewer aborted procedures
7% vs 21%, (p<0.0001)
Marmo R, et al. Gastrintest Endosc Aug; 72(2):

23. Patient acceptance of split-dose bowel prep
In comparisons bet split dose and conventional:
Higher patient satisfaction scores
Higher “no or minimal difficulty” completing
No significant difference in percentage of patients who stop for a bowel movement on way to proc
No difference in compliance
Khan, MA, et al. J Clin Gast. 2010; 44(4):310-1 (Letter)
Park, JS, etal. Endoscopy. 2007; 39(7):616-9
Majority of patients willing to get up early to take split dose Rex DK, et al. Dig Dis Sci. 2010; 55(7):

24. Anaesthetic concerns re morning prep
Traditionally patients have fasted overnight for colonoscopy
Some anaesthetists argue that aspiration risk higher if morning prep is taken
But residual gastric fluid volume similar between split-dose regimen vs conventional Huffman M, Gastrointest Endosc Sep; 72(3):
Anaesthetic guidelines have reduced precolonoscopy fasting to 2 hours.

25. Image Enhanced Colonoscopy
Includes:
Endoscope based image enhancing:
NBI (Olympus)
iScan(Pentax)
Chromoendoscopy
Indigo carmine dye

29. NBI/FICE/iScan
iScan (Pentax) increases detection of neoplasia over white light (38% vs 13%)
FICE (Fuji) showed no difference in adenoma detection over white light
NBI (Olympus) increases detection of flat adenomas over white light, but not adenomas overall.
FICE (Pentax) vs Indigocarmine – no difference in adenoma detection rates
Hoffman A. et al. Endoscopy (10):827-33
Chung SJ, et al. Gastrointestinal Endoscopy. 2010; 72(1):136-42
Paggi S, et al. Clin Gas & Hep. 2009; 7(10)
Pohl J, et al. Gut. 2009; 58(1):73-8

30. Chromoendoscopy
Spraying of indigo carmine through the flushing channel of the colonoscope
Increases detection of flat lesions and hyperplastic polyps, but not of adenomas overall Le Rhun M, et al. Clin Gas & Hep. 2006; 4(3):349-54

31. What makes a colonoscopy a (good) colonoscopy?
SPLIT DOSE COLONIC PREP
At least 6 minutes withdrawal
+/- image enhancing in the R colon (NBI or indigo carmine)
Endoscopist consciously looking for flat R sided lesions

32. Endoscopist Report Card
Ultimately all endoscopists should audit their adenoma detection rate
My performance in 81 colonoscopies between Mar and May 2013 at 1 facility:
Successful caecal intubation
100%
Split Prep
Prep “good or satisfactory”
93%
Complications 0%
Adenoma Detection Rate
(incl SSA)
45.6%
SSA percentage of all polyps
18.9%
SSA detection rate
8.7%