Patients with
choledochal cyst often have repeated attacks of
abdominal pain accompanied by
hyperamylasemia, and they may be diagnosed as having
acute pancreatitis. However, the attacks generally tend to subside in a short period by
conservative treatment, and evidence of
pancreatitis is rarely observed at the time of surgery.
Choledochal cyst is commonly associated with pancreatobiliary maljunction, and high concentrations of pancreatic
enzymes in bile are usually observed. When the bile duct pressure increases due to obstructive
cholangitis, pancreatic
enzymes in bile may regurgitate into the blood stream. Cholangiovenous reflux of
amylase might cause
hyperamylasemia. In order to investigate the mechanism of
hyperamylasemia by cholangiovenous reflux, canine pancreatic juice or bile from a patient with
choledochal cyst was injected into the obstructed common bile duct in dogs. The pancreatic
enzymes in bile could readily enter into the blood stream at the pressure level of 15 mmHg or more in the bile duct. The peak
amylase level in the thoracic lymph was observed to be more than 4 times higher than that in the blood serum, and the lymph flow during 30 minutes increased significantly from 8.1 to 20.4 ml at the bile duct pressure level of 20 mmHg. The reflux of
amylase in bile into the blood stream via both the hepatic vein and thoracic duct might result in
hyperamylasemia in the patients with
choledochal cyst.