Spontaneous Bile Flow in the Pancreatic Duct

We read with interest the paper by Pohle et al. describing spontaneous flow of bile through the human pancreatic duct in the absence of pancreatitis - ”nature’s human experiment” [1]. The authors report the case of a 16-year-old girl in whom a congenital biliopancreatic fistula allowed continuous flow of bile through a large portion of the pancreatic duct, which was associated with cholangitis but had never led to pancreatitis. They therefore concluded that their case was the first human experience suggesting that pancreatic duct obstruction might provide the main hypothesis to explain the pathogenesis of gallstone-induced pancreatitis, instead of biliary reflux into the pancreatic duct. We also recently treated a patient with a similar case.

A 54-year-old woman was admitted to our hospital due to discomfort in the right upper quadrant. Abdominal ultrasonography revealed a dilation in the common bile duct, and she was investigated further. She had never experienced an attack of cholangitis. The physical examination was unremarkable. Serum alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase, alkaline phosphatase, and amylase levels were all within normal limits. The complete blood count was normal. Computed tomography of the abdomen showed dilation of the common bile duct and a normal pancreas. Endoscopic ultrasonography demonstrated a dilated common bile duct opening into the pancreatic duct and a normal pancreas. Endoscopic retrograde cholangiopancreatography (ERCP) showed a dilated common bile duct, opening into the pancreatic duct; the distal end of the common bile duct was tapered and narrowed and had a hook shape at its junction with the pancreatic duct (Figure [1]). The pancreatic duct was dilated after joining the common bile duct and was normal distally. Following ERCP, the patient experienced a cholangitis attack, which resolved with medical treatment. The patient was followed on an outpatient basis without any need for further treatment.

Figure 1 The endoscopic retrograde cholangiopancreatogram shows a dilated common bile duct, opening into the pancreatic duct. The distal end of the common bile duct is tapered and narrowed and has a hook shape at its junction with the pancreatic duct.

The patient had also never experienced a pancreatitis attack, despite a congenital anomaly allowing continuous flow of bile into the pancreatic duct for more than 50 years. This observation lends support to the theory suggesting that biliary pancreatitis cannot develop without an obstruction in the pancreatic duct.

Pohle et al. [1] state that the abnormal junction between the pancreatic duct and the bile ducts within the pancreas would be expected to allow reflux of pancreatic juice into the biliary tract, weakening the bile duct wall and thus resulting in dilation of the duct. However, we do not agree with this theory. In both of these patients, the distal end of the common bile duct was tapered and narrowed and had a hook shape at its junction with the pancreatic duct. A similar finding is observed in biliary opening anomalies in which the common bile duct and pancreatic duct open separately into the postbulbar region and there is no reflux of pancreatic juice into the biliary tract [2]. Dilation of the common bile duct is observed in almost all of these patients and is due to the opening angle and partial narrowing of the common bile duct at the level of its opening into the duodenal bulb.

In summary, we agree with Pohle et al. that obstruction of the pancreatic duct is the principal hypothesis in the pathogenesis of gallstone-induced pancreatitis. However, we consider that narrowing and the opening angle of the distal end of the common bile duct at the level of its junction with pancreatic duct explains the pathogenesis of common bile duct dilation.

References

• 1 Pohle T, Konturek J W, Domschke W, Lerch M M. Spontaneous flow of bile through the human pancreatic duct in the absence of pancreatitis: nature’s human experiment.  Endoscopy. 2003;  35 1072-1075
• 2 Lee S S, Kim M H, Lee S K. et al . Ectopic opening of the common bile duct in the duodenal bulb: clinical implications.  Gastrointest Endosc. 2003;  57 679-682