Reproducibility and accuracy of visual estimation of polyp size in large colorectal polyps

Figures & data

Table 1. Demographics.

	Patients (n = 40)
Age (years)	70.6 ± 8.6
Sex (male)	22 (55.0 %)
Indication of primary colonoscopy
National screening program*	19 (47.5 %)
Symptoms	14 (35.0 %)
Surveillance^θ	4 (10.0 %)
Miscellaneous	3 (7.5 %)
Interval between colonoscopies (days)	29.3 ± 32.4
	Polyps (n = 45)
Measurement reference (OC2)
2 cm snare	2 (5.3 %)
2.5 cm snare	26 (68.4 %)
3 cm snare	1 (2.6 %)
4 cm snare	7 (18.4 %)
ESD-instruments	1 (2.6 %)
Endoscope (while looping)	1 (2.6 %)
Not specified	7 (18.4 %)
EMR/ESD	38 (84.4%)/7 (15.6 %)
Polyp location	Primary colonoscopy	Secondary colonoscopy
Caecum	8 (17.8%)	7 (15.6%)
Ascending colon	4 (8.9%)	8 (17.8%)
Hepatic flexure	2 (4.4%)	–
Transverse colon	3 (6.7%)	4 (8.9%)
Splenic flexure	4 (8.9%)	2 (4.4%)
Descending colon	1 (2.2%)	2 (4.4%)
Sigmoid colon	11 (24.4%)	12 (26.7%)
Rectum	10 (22.2%)	10 (22.2%)
Not specified	2 (4.4 %)	–
Polyp morphology	Primary colonoscopy	Secondary colonoscopy
Pedunculated	10 (22.2%)	13 (28.8%)
Sessile	22 (48.9%)	25 (55.6%)
Non-polypoid	9 (20.0%)	7 (15.6%)
Not specified	4 (8.9 %)	–
Histology
Hyperplastic	3 (6.7%)
Sessile serrated adenoma	3 (6.7%)
Tubular adenoma	29 (64.4%)
Tubulovillous adenoma	8 (17.8%)
Villous adenoma	–
Adenocarcinoma	2 (4.4%)
Dysplasia (n = 40)
None	1 (2.5%)
Low grade dysplasia	36 (90.0%)
High grade dysplasia	3 (7.5%)

Continuous variables are presented as means with standard deviation. Ordinal and binary variables are presented with percentages. *First colonoscopy after a positive fecal immunochemical test. ^θSurveillance are control colonoscopies after polypectomy 1–5 years earlier. OC2: secondary optical colonoscopy. EMR: endoscopic mucosal resection. ESD: endoscopic submucosal dissection.

Figure 1. OC1 vs OC2 with 95% LA. On the left-hand side a scatter plot comparing in-situ measurements of both colonoscopies. On the right-hand side a Bland–Altman plot showing the differences between the measurements in comparison to the average of both measurements as well as 95% limits of agreement (horizontal lines on equal distance from the mean). OC1: primary optical colonoscopy. OC2: secondary optical colonoscopy. LA: limits of agreement.

Table 2. Average difference between size measurements.

	95% LA	Difference in mm (95% CI)	p Value
OC1 vs. OC2 (n = 37)	−14.2–19.0	2.4 (−0.4–5.2)	.09
OC1 vs. postfixation (n = 26)	−13.2–16.9	1.8 (−1.2–4.9)	.23
OC2 vs. postfixation (n = 33)	−8.9–9.1	0.1 (−1.5–1.8)	.88
OC2 vs. prefixation (n = 35)	−10.6–9.0	−0.8 (−2.5–0.9)	.35
Prefixation vs. postfixation (n = 33)	−5.6–7.6	1.0 (−0.2–2.2)	.09

p-Value of a two-sided paired t-test comparing the means of different size measurements. LA: limits of agreement. CI: confidence interval; OC1: primary optical colonoscopy; OC2: secondary optical colonoscopy.

Table 3. Agreement on ≥20 mm polyp sizes.

	Observed agreement	Cohen’s Kappa (95 % CI)	p Value
OC1 vs. OC2 (n = 37)	83.8 %	0.65 (0.60–0.70)	.00
OC1 vs. post-fixation (n = 26)	81.5 %	0.63 (0.56–0.69)	.00
OC2 vs. post-fixation (n = 33)	93.9 %	0.88 (0.76–0.94)	.00
Pre-fixation vs. post-fixation (n = 33)	93.9 %	0.88 (0.83–0.93)	.00

CI: confidence interval; OC1: primary optical colonoscopy; OC2: secondary optical colonoscopy.