Risk factors for postoperative stone formation in pediatric choledochal cysts: a study of 457 cases.

Postoperative bile duct stones, including intrahepatic bile duct (IHD) stones and remnant distal common bile duct (remnant intrapancreatic common bile duct, RIPD) or common channel duct (CCD) stones, are long-term complications following choledochal cyst (CC) excision. We aimed to retrospectively review occurrence, associated factors, and treatment of postoperative bile duct stones. Records of 457 pediatric patients who underwent CC excision at Asan Medical Center (1992-2021) were retrospectively reviewed. Data on cholelithiasis, operation, and outcomes were analyzed. Overall, 457 pediatric patients underwent CC excision, with 21 developing intrahepatic duct (IHD) stones, primarily associated with Todani type IVa cysts, especially Tsuchida types 2 or 3, which are often linked to IHD dilation and upstream stenosis. Patients with RIPD/CCD stones were all identified with complicated Komi types, and the impact of pancreas divisum itself was unclear. Early surgery even before 6 months of age is associated with improved prognosis regarding the occurrence of IHD stones, but not related with RIPD/CCD stones. This is the largest retrospective study to date, comprising 21 IHD and 18 RIPD/CCD stones from 457 pediatric patients with CCs and their clinical outcomes. We found that the structural characteristics of the bile duct influence stone formation. In addition, our findings indicate the need for more systematic and long-term follow-up of patients with CCs after surgery.