Strategies for achieving successful cannulation in endoscopic retrograde cholangiopancreatography: A technical overview

Table 2 Selected studies with identified risk factors for difficult canulation[23,24,26,29-31]

Ref.	Number of patients	Identified risk factors
Noda et al[30]	102	Type III (enlarged/protruding) papillary morphology
		Absence of the ampullary bile duct
Saito et al[31]	1406	Non-expert endoscopist
		Low-volume center
		Absence of cholangitis
		Normal serum bilirubin
		Intradiverticular papilla
		Type of major papilla
Cáceres-Escobar et al[24]	498	Gender female
		Acute care hospital setting
		Redundant papilla
		Peridiverticular papilla
		Pancreatic cancer
Chen et al[23]	286	Small papilla
		Protruding papilla
		Malignant bowel obstruction
		Age
Tabak et al[29]	614	Periampullary diverticum
		Ampullary carcinoma
		Papillary anatomy
Williams et al[26]	3209	Billroth surgery
		Multiple/large stones
		Old age
		Physical status
		Presence of trainee
		Suspected biliary stricture
		Ampullary tumor