Under pressure: choledochal malformation manometry

Abstract

Purpose The cause of choledochal (cystic or fusiform) malformation is not known. A favoured hypothesis suggests that abnormal reflux of activated pancreatic secretions via a common pancreatobiliary channel may initiate mucosal injury and mural weakness leading to bile duct dilatation, at normal intraduct pressures. However, bile duct pressures in both normal or disease states are not known in such children. Methods Intraoperative choledochal pressure (CP) measurements were made before any other manipulation. Bile was cultured and its amylase content measured. Biochemical liver function (bilirubin, aspartate aminotransferase, γ-glutamyl transpeptidase, and alkaline phosphatase) was measured. Data were quoted as median (interquartile range). Statistical tests were parametric, where appropriate, and P = .05 was regarded as significant. Results Twenty-five children (age 2.5 [1.25-5.91] years) with choledochal (cystic [n = 13] and fusiform [n = 12]) malformation coming to surgery were studied. Median CP was 13 (8.5-17) mm Hg. Median bile amylase was 6722 (241-18,000) IU/L. Choledochal pressure inversely correlated with bile amylase ( r = −0.60, P = .001), serum aspartate aminotransferase ( r = 0.46, P = .01), and log γ-glutamyl transpeptidase ( r = 0.4, P = .04) but not with bilirubin ( P = .11), alkaline phosphatase ( P = .20), or age ( P = .11). No difference in CP, bile amylase, or liver biochemistry could be identified between the 2 biliary phenotypes. All bile cultures were sterile. Conclusions Increased CP is inversely related to the level of bile amylase (and hence degree of the functional common channel). This suggests that obstructive stenosis at the level of the pancreato-biliary junction (but not the ampulla) may be a causal factor in a proportion of choledochal malformations.