This study aims to assess the long-term postoperative changes in the preoperative dilated intrahepatic bile duct (IHBD) in pediatric patients with congenital biliary dilatation (CBD).

The postoperative serial changes in the preoperative dilated left IHBD in pediatric patients who underwent appropriate excision surgery were evaluated using magnetic resonance cholangiopancreatography (MRCP).

The IHBD dilation significantly decreased at a median of 1.5 years and was maintained up to 15 years postop in the 24 CBD patients, regardless of the methods of biliary reconstruction. In the 16 patients with apparent preoperative IHBD dilation (5 mm or more), a significant rapid decrease was also observed and maintained up to 15 years postop, regardless of age at surgery. However, a patient with failed rapid reduction at 1.5 years postop and sustained IHBD dilatation of more than 5 mm developed cholangitis 15 years postop with suspected residual congenital stenosis at the hepatic hilum.

Performing the appropriate excision surgery resulted in a rapid reduction of the preoperative IHBD dilation and maintained long-term reduced IHBD dilation. Patients with failed rapid reduction and sustained dilatation of the IHBD would have residual stenosis and should be carefully followed up for possible late cholangitis.