Colonoscopic Localisation Accuracy

for Colorectal Resections

Damian IannoBBiom (Hons), Third Year Medical Student, Austin Hospital

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

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

Objectives• To assess the accuracy of colonoscopic localisation

and its effect on clinical practice

• To assess factors associated with incorrect colonoscopic localisation

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

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

Division of colon into segments

Sigmoid colon

Splenic flexure

Rectosigmoid colon

Descending colon

Rectum

Ascending colon

Transverse colon

Caecum

Hepatic flexure

Ileum

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%)

Parameter Concordant (175) Non-concordant (46) PGender (M/F) 105/70 25/21 0.600Age (years) 67.39 (±1.76) 70.82 (±3.21) 0.087Time (minutes) 26.69 (±2.12) 25.61 (±3.43) 0.92Size (millimetres) 38.37 (±3.11) 40.57 (±4.92) 0.206Previous resection 8/175 (4.57%) 2/46 (4.35%) 0.739Tattoo 76/175 (43.4%) 24/46 (52.17%) 0.371Distance from anal verge 59/175 (33.7%) 13/46 (28.3%) 0.559Prep 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

Parameter Concordant (175) Non-concordant (46) Accuracy, % PClinicians’ Background-Colorectal-Gastroenterology-General Surgery

93 757

15 30 1

86.1%71.4%87.5%

0.026

Level of Training- Consultant- Fellow - Nurse - Registrar

76 436 48

20 8 5 13

79.2%84.3%54.5%78.7%

0.184

Distribution of reported location of lesions on colonoscopy

Sigmoid colon

Splenic flexure

Rectosigmoid colon

Descending colon

Rectum

Ascending colon

Transverse colon

Caecum

Hepatic flexure

IleumUnknown1%

17%

10%

7%

5% 1%

6%

25%

7%

20%1%

Location of incorrectly localised lesions on colonoscopy

Sigmoid colon

Splenic flexure

Rectosigmoid colon

Descending colon

Rectum

Ascending colon

Transverse colon

Caecum

Hepatic flexure

IleumUnknown1% 0%

17% 7%

10% 11%

7% 20%

5% 4% 1% 4%

6% 9%

25% 24%

7% 20%

20% 0%1% 2%

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

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

Results

Changes in surgery Reason n

Lap → open conversion for operative reasons - Adhesions - Local invasion - Poor views

224

• 8 of the 17 lesions that required changes to intended surgery were due to operative reasons

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!

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)

11

1

1

1

3

1

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

Limitations• Retrospective study• Heterogeneous group• Observer bias → colorectal surgeon likely to be

both endoscopist and surgeon • No standardised method of description for

location

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

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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