Risk factors associated with missed colorectal flat adenoma: A multicenter retrospective tandem colonoscopy study

Table 4 “Per-adenoma” miss rates and risk factors in detection of advanced flat adenomas during colonoscopy n (%)

Factor	Total (n = 205)	Diagnosed (n = 181)	Missed (n = 24)	χ2test	P value
Size				17.796	< 0.001
< 10 mm	33	22 (66.7)	11 (33.3)
≥ 10 mm	172	159 (92.4)	13 (7.6)
Location				11.838	0.003
Rectum	68	67 (98.5)	1 (1.5)	1.127	0.2881
Left colon	36	32 (88.9)	4 (11.1)
Right colon	101	82 (81.2)	19 (18.8)
Pathologic classification				0.025	0.874
Tubular	57	50 (87.7)	7 (12.3)
Tubulovillous and villous	148	131 (88.5)	17 (11.5)
Age (yr)				1.157	0.282
< 60	98	89 (90.8)	9 (9.2)
≥ 60	107	92 (86.0)	15 (1.4)
Bowel preparation				13.815	< 0.001
Good	162	150 (92.6)	12 (7.4)
Poor	43	31 (72.1)	12 (27.9)
Proficiency				1.078	0.583
> 1000 cases	135	120 (88.9)	15 (11.1)
500-1000 cases	55	49 (89.1)	6 (10.9)
< 500 cases	15	12 (80.0)	3 (20.0)
Specialty				6.167	0.013
Gastroenterologist	156	146 (93.6)	10 (6.4)
Non- gastroenterologist	49	35 (71.4)	14 (28.6)
Operative mode				2.272	0.132
One-person technique	161	145 (90.1)	16 (9.9)
Two-person technique	44	36 (81.8)	8 (18.2)
Withdrawal time
≥ 6 min	145	129 (89.0)	16 (11.0)	0.217	0.641
< 6 min	60	52 (86.7)	8 (13.3)

¹Comparison between the left and right colon.