This document discusses a study assessing the accuracy of colonoscopic localization of colorectal lesions prior to surgical resection. The study found that colonoscopic localization was incorrect in 20.8% of cases, and in 4% of cases this resulted in changes to the planned surgical procedure. Incomplete colonoscopies were a significant factor in incorrect localization. While CT scans provided additional information, they could not reliably localize lesions on their own. The study concludes that emphasis on precise localization during colonoscopy training is important to optimize patient outcomes for colorectal resections.

1. Colonoscopic Localisation Accuracy
for Colorectal Resections
Damian Ianno
BBiom (Hons), Third Year Medical Student, Austin Hospital

2. Background
•CRC: Second most common cancer in Australia
•Colonoscopy: ‘Gold standard’
•Sensitivity of colonoscopy: 85-95%
•Lesion localisation: 80-90%, in setting of open
resection

3. Background
• Laparoscopic assisted resections: Common
• Correct localisation of lesions is essential to
achieving optimal patient outcomes, given
incorrect localisation can lead to:
- Change in intended operation
- Change in bowel segment removed
- Incorrect segment of bowel being removed

4. Objectives
• To assess the accuracy of colonoscopic localisation
and its effect on clinical practice
• To assess factors associated with incorrect
colonoscopic localisation

5. Methods
• Retrospective study
• University teaching hospital
• Inclusion: Patients who underwent colonic
resection after pre-operative colonoscopy
between 2008 and 2013 for a mass lesion
• Exclusion: Other institutions, non-mass lesion
• Scanned medical records: Demographic,
endoscopic, operative and pathological records

6. Methods
• The data was analysed with SigmaPlot 12.0
• Mann-Whitney rank sum and chi-square tests
were used where appropriate with 95% confidence
intervals given
• A p value of <0.05 was deemed statistically
significant

7. Division of colon into segments
Sigmoid colon
Splenic flexure
Rectosigmoid colon
Descending colon
Rectum
Ascending colon
Transverse colon
Caecum
Hepatic flexure
Ileum

8. Demographic Values
Age, years: Mean (SD); range 68.1 (±12.1); 25-92
Sex: n male (%) 130 (61.9%)
Patients: n 210
Lesions: n 221
Complete colonoscopy achieved: n (%) 164 (74.2%)
Incorrectly localised lesions: n (%) 46 (20.8%)

9. Parameter Concordant (175) Non-concordant (46) P
Gender (M/F) 105/70 25/21 0.600
Age (years) 67.39 (±1.76) 70.82 (±3.21) 0.087
Time (minutes) 26.69 (±2.12) 25.61 (±3.43) 0.92
Size (millimetres) 38.37 (±3.11) 40.57 (±4.92) 0.206
Previous resection 8/175 (4.57%) 2/46 (4.35%) 0.739
Tattoo 76/175 (43.4%) 24/46 (52.17%) 0.371
Distance from anal verge 59/175 (33.7%) 13/46 (28.3%) 0.559
Prep quality
- Good
- Satisfactory
- Poor
- Not Recorded
83 (47.4%)
65 (37.1%)
21 (12.0%)
6 (3.43%)
21 (45.7%)
19 (41.3%)
3 (6.5%)
3 (6.5%)
0.562
Complete scope 143/175 (81.7%) 28/46 (60.9%) 0.005

10. Parameter Concordant (175) Non-concordant (46) Accuracy, % P
Clinicians’ Background
- Colorectal
- Gastroenterology
- General Surgery
93
75
7
15
30
1
86.1%
71.4%
87.5%
0.026
Level of Training
- Consultant
- Fellow
- Nurse
- Registrar
76
43
6
48
20
8
5
13
79.2%
84.3%
54.5%
78.7%
0.184

11. Distribution of reported location of lesions on colonoscopy
Sigmoid colon
Splenic flexure
Rectosigmoid colon
Descending colon
Rectum
Ascending colon
Transverse colon
Caecum
Hepatic flexure
Ileum
Unknown1%
17%
10%
7%
5% 1%
6%
25%
7%
20%
1%

12. Location of incorrectly localised lesions on colonoscopy
Sigmoid colon
Splenic flexure
Rectosigmoid colon
Descending colon
Rectum
Ascending colon
Transverse colon
Caecum
Hepatic flexure
Ileum
Unknown1% 0%
17% 7%
10% 11%
7% 20%
5% 4% 1% 4%
6% 9%
25% 24%
7% 20%
20% 0%
1% 2%

13. Results
• Analysis of pre-operative CT records
CT Values
CT performed pre-operatively: n (%) 196/221 (88.7%)
CT sensitivity in identifying lesion: n (%) 116/196 (59.2%)
CT correctly localised lesion: n (%) 84/116 (72.4%)
CT correctly localised non-concordant
lesion: n (%)
17/44 (38.6%)
Note: Only 44 of 46 non-concordant lesions had pre-operative CT performed

14. Results
• Total of 46 incorrectly localised lesions
• 17 lesions required changes to intended surgery
• 29 lesions did not:
- CT aided correct localisation for 6 lesions
- In remaining 23 cases, changes minor enough to
not necessitate changes in surgical planning

15. Results
Changes in surgery Reason n
Lap → open conversion for operative reasons - Adhesions
- Local invasion
- Poor views
2
2
4
• 8 of the 17 lesions that required changes to
intended surgery were due to operative reasons

16. Results
• 9 of the 17 lesions that required changes to
intended surgery were due to incorrect location
Of the 221 lesions in total, over 4% required
changes to surgical procedure due to inaccurate
localisation!

17. Colonoscopic location (planned procedure) --> Actual location (actual procedure) n
• Sigmoid (open left hemicolectomy) --> Caecum (open right hemicolectomy)
• Descending colon (laparoscopic anterior resection) --> Transverse colon (open
extended right hemicolectomy)
• Hepatic flexure (open extended right hemicolectomy --> Caecum
(open right hemicolectomy)
• Hepatic flexure (laparoscopic right hemicolectomy) --> Transverse colon
(laparoscopic extended right hemicolectomy)
• Hepatic flexure (laparoscopic extended right hemicolectomy) --> Ascending colon
(laparoscopic right hemicolectomy)
• Sigmoid (laparoscopic anterior resection) --> Rectum (laparoscopic low anterior
resection)
• Splenic flexure (laparoscopic left hemicolectomy) --> Descending colon
(laparoscopic anterior resection)
1
1
1
1
1
3
1

18. Discussion
• Overall accuracy in line with other studies (≈80%)
• Incomplete scope a significant factor in incorrect
localisation → deprived of important landmarks
• Emphasis on location may be higher amongst
colorectal surgeons → consideration for resection
• CT, although helpful, cannot be relied upon to
correctly localise lesions, especially when
colonoscopy has been unreliable

19. Limitations
• Retrospective study
• Heterogeneous group
• Observer bias → colorectal surgeon likely to be
both endoscopist and surgeon
• No standardised method of description for
location

20. Conclusion
• Incorrect localisation can have serious clinical
consequences
• Localisation is particularly inaccurate if the
colonoscopy is not complete
• Endoscopy training should have a higher
emphasis on correct identification of lesion
location on colonoscopy

21. Conclusion
• All lesions not in rectum or at caecal pole should
be tattooed to help intraoperative localisation if
resection is being considered
• A formal guideline to describe position in the
colon should be created

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