Intrahepatic duct dilatation in type 4 choledochal malformation: pressure-related, postoperative resolution

BackgroundType 4 choledochal malformations (CMs) may be defined as those with both intrahepatic and extrahepatic bile duct dilatation. The aims of this study were to investigate possible causes of intrahepatic duct (IHD) dilatation in CM and to define the effect of surgery over time.MethodsThis study was a single-center retrospective review of a database of all children with CM undergoing surgery (excision of extrahepatic bile duct dilatation and hepaticojejunostomy) and identified as type 4 (on imaging and at surgery). Data included intraoperative choledochal pressure measurements and biliary amylase content and were expressed as median (interquartile range [IQR]). All comparisons used nonparametric statistical tests. P ≤.05 was regarded as significant.ResultsTwenty children were identified as type 4 CM (age, 4.3 years; range, 2.7-10.4 years) with preoperative IHD dilatation (right duct: diameter [range], 8.5 [4.5-14] mm; left: 8 [4-14.5] mm). Median intraoperative choledochal pressure was 17 (8-27) mm Hg (normal, <5 mm Hg), and intraoperative bile amylase was 3647 (range, 500-58 000) IU/L (normal, <100 IU/L). Preoperative IHD diameter correlated with choledochal pressure (right: rs=0.46, P = .03; left: rs=0.34, P = .07) but not with biliary amylase (P = .28 and P = .39, respectively).At 1 year postsurgery, median (range) IHD diameter had decreased to 1 (1-2.5) mm for right duct (P = .0002) and 1.5 (1-3) mm for left duct (P = .0006) and remained stable for up to a 10-year follow-up.ConclusionOur data suggest that IHD dilatation is related to sustained increased intrabiliary pressure rather than any intrinsic intrahepatic CM. Effective surgery invariably reduces measured IHD toward normal values.