Role of ultrasound in follow-up after choledochal cyst surgery.

Choledochal cyst, which is a congenital dilatation of the bile duct, is a common congenital disease requiring surgical repair. This disease usually occurs in children aged < 10 years, necessitating a relatively long follow-up after repair. The incidence of this congenital disease in Asian countries, including Japan, was reported to be higher than that in other countries. Thus, follow-up of pediatric patients after choledochal cyst surgery is especially important in Japan. Specific or non-specific choledochal cyst repair complications occur in various organs and are categorized as early or late complications. In the liver, biliary obstruction, such as an anastomotic stricture or intrahepatic bile duct stone, may occur. Biliary carcinoma is an important late complication. In the pancreas, pancreatitis, residual bile duct dilation, or pancreatic fistula/leakage may occur. In the intestines, Roux-en-Y reconstruction complications, such as an obstruction at the site of anastomosis or retrograde intussusception, may occur in the early and late phases. Some complications warrant urgent surgical intervention. In this review, we present the sonographic findings of choledochal cyst repair complications to guide clinicians in conducting a careful evaluation of the involved organs in the presence of these complications.