Difficult colorectal polypectomy: Technical tips and recent advances

Table 1 The Japan Narrow-band Imaging Expert Team classification[8]

	Type 1	Type 2A	Type 2B	Type 3
Vessel pattern	Invisible	Regular caliber, regular distribution (meshed/spiral pattern)	Variable caliber, irregular distribution	Loose vessel areas, interruption of thick vessels
Surface pattern	Regular dark or white spots, similar to surrounding normal mucosa	Regular (tubular/branched/papillary)	Irregular or obscure	Amorphous areas
Suspected pathology	Hyperplastic polyp/sessile serrated polyp	Low grade intramucosal neoplasia	High grade intramucosal neoplasia/shallow submucosal invasive cancer	Deep submucosal invasive cancer

Table 2 Characteristics of the difficult colorectal polyps

Size	> 20 mm
Location	Near or involving the appendiceal orifice
	Ileocecal valve
	Anorectal junction
	Behind the fold
	Angulated segment
Morphology	Pedunculated polyp with thick stalk and large head
	Laterally spreading tumor
	Submucosal fibrosis or positive non-lifting sign
Special situation	Recurrent lesion
	Strong colonic peristalsis

Table 3 Size/Morphology/Site/Access scoring system[19]

Parameter	Range	Score
Size	< 1 cm	1
	1.0-1.9 cm	3
	2.0-2.9 cm	5
	3.0-3.9 cm	7
	> 4 cm	9
Morphology	Pedunculated	1
	Sessile	2
	Flat	3
Site	Left	1
	Right	2
Access	Easy	1
	Difficult	3

Size/Morphology/Site/Access (SMSA) level 1: 4-5 points, level 2: 6-8 points, level 3: 9-12 points, level 4: > 12 points.

Table 4 Indications for colorectal endoscopic submucosal dissection[10]

	Lesions requiring enbloc resection
1	Lesions which en bloc resection with EMR is difficult
	LST-NG, particularly LST-NG with pseudo-depressed type
	Lesions with VI-type pit pattern
	Carcinoma with shallow T1 invasion
	Large depressed-type tumor
	Large protruded-type lesions suspected to be carcinoma
2	Mucosal tumors with submucosal fibrosis
3	Sporadic tumors in conditions of chronic inflammation such as ulcerative colitis
4	Local residual or recurrent early carcinomas after endoscopic resection

EMR: Endoscopic mucosal resection; LST-NG: Laterally spreading tumor non-granular type.