Normal and anomalous pancreaticobiliary union in children and adolescents.

Background: The normal length of the pancreaticobiliary union (common channel) in the pediatric population is not known, nor is the frequency of anomalous pancreaticobiliary union and the extent to which it is associated with pancreaticobiliary disease.

Methods: ERCP was performed on 136 patients younger than 1 year (group 1) and 128 older than 1 year (group 2).

Results: In group 1 the average length of the common channel was 1.8 +/- 0.61 mm with a maximal length of 3 mm (mean plus 2 standard deviations). In group 2 the average length and maximal length of the common channel increased with age. In the 1 to 3 year age range the average length was 2.2 +/- 0.47 mm with a maximal length of 2.7 mm, in the 4 to 6 year range it was 2.8 +/- 0.40 mm (3.6 mm maximal), in the 7 to 9 year range it was 3.2 +/- 0.43 mm (4.1 mm maximal), in the 10 to 12 year range it was 3.9 +/- 0.5 mm (4.4 mm maximal), and in the 13 to 15 year range it was 4.0 +/- 0.51 mm (5 mm maximal). The prevalence of the anomalous pancreaticobiliary union was 25% (66/264). In group 1 the anomaly was present in 4.4% (6 of 136) of patients, 1.3% (1/76) with neonatal hepatitis, 4.6% (3/44) with biliary atresia, and 100% (2/2) with choledochal cyst. In group 2 the anomaly was present in 46.9% (60/128) of patients, 100% (57/57) with choledochal cyst and 15.7% (3/19) with idiopathic recurrent pancreatitis without bile duct dilatation.

Conclusions: The mean length of the common channel increases with age. The maximum normal length of the common channel in neonates and infants younger than 1 year is 3 mm. It increases with age to a maximum of 5 mm in children and adolescents between 13 and 15 years of age. Anomalous pancreaticobiliary union is relatively common among children and adolescents undergoing ERCP in our center, including those with idiopathic recurrent pancreatitis (15.7%). ERCP is valuable in the diagnosis of this anomaly.