ObjectiveTo compare Roux-en-Y hepatico-jejunostomy with complete resection of the cyst or incomplete resection with 1-cm remnant proximal cyst wall in treating adult type I choledochal cyst (CC).MethodsThe medical records of 267 adult patients with type I CC from January 1998 to December 2015 were reviewed retrospectively. Among them, 171 underwent Roux-en-Y hepatico-jejunostomy with complete resection (PBD 0-cm group) and 96 underwent Roux-en-Y hepatico-jejunostomy with 1-cm proximal cyst wall left (PBD 1-cm group). The short- and long-term post-operative complications were compared between the two groups.ResultsNo significant difference was observed in operative time or anastomotic diameter between the two groups. The incidence of perioperative complications was significantly higher in the PBD 1-cm group than that in the PBD 0-cm group (28.1% vs 14.0%, p=0.005), especially post-operative cholangitis (7.3% vs 1.2%, p=0.021). The incidence of long-term post-operative complications was not significantly different, including anastomotic stricture, reflux cholangitis, intra-hepatic bile duct stones and bile leak (all p >0.05). Post-operative intra-pancreatic biliary malignancy occurred in one patient in the PBD 0-cm group at 25 months and one patient in the PBD 1-cm group at 5 month, respectively. Anatomical site malignancy was observed in one patient in the PBD 1-cm group at 10 months.ConclusionEase of performing anastomosis does not justify retaining a segment of choledochal cyst in type I CC due to its higher risk of post-operative complication and malignancy. A complete excision of the CC with anastomosis to the healthy proximal bile duct is necessary in treatment of type I CC.