Biliary Microlithiasis

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Biliary Microlithiasis - Pancreatitis

Idiopathic Pancreatitis

Foci passing through the CBD may be relatively common but it is uncommon for a circumstance resulting in pancreatitis. The pancreatic duct is a low pressure system, no contractions, multiple varied sized ducts, fragile to pressure and easily obstructed compared to the CBD. The CBD is a simple high pressure tubular system with wall contractions and one point of exit clearing most obstruction by foci relatively easily with or without causing pain. This circumstance creates a potential pressure gradient from the CBD to the pancreatic duct. In normal conditions pressures generated by CBD wall contractions to expel bile may force foci into the low pressure pancreatic duct sporadically due to this pressure gradient, which by itself would not likely cause pancreatitis. Pancreatitis could result with an appropriate anatomical relationship wherein the pancreatic duct enters into the CBD ampulla; a saccular dilatation at this level could be more facilitating for obstruction by foci. The impaction of multiple foci in the ampulla could obstruct the main pancreatic duct orifice resulting in extensive pancreatitis. Foci obstructing in the ampulla distal to the origin of the pancreatic duct, could re-route foci from the high pressure CBD into the low pressure pancreatic duct causing obstruction in small pancreatic ducts resulting in localized pancreatitis. Intermittent RUQ pain is likely due to foci passing through the ampulla and if persistent enough may create edema resulting in pancreatitis.

All patients referred as idiopathic pancreatitis had foci. 50% had intermittent RUQ pain prior to the onset of pancreatitis. Some patients with or without tolerable minimal to mild intermittent RUQ pain, suddenly develop undiagnosed constant moderate to severe upper abdominal pain, lasting from a few hours to a few days. Without risk factors and especially with a normal routine gallbladder ultrasound, low grade pancreatitis is not considered as an etiology so appropriate tests are not ordered. This may be sub-clinical or minor pancreatitis. Foci found in this clinical circumstance should increase the index of suspicion for sub clinical or minor pancreatitis.

We believe cholecystectomy should not be done primarily for biliary microlithiasis. There is still “the same” pain and recurrent pancreatitis after cholecystectomy which supports our theory that foci are formed in the cystic duct in valves of Heister.

Gallstone pancreatitis

This statement may assume gallstones would have to impinge in the ampulla and orifice of the pancreatic duct area to cause pancreatitis. The definition of gallstones > 2mm, would not often include stones small enough to pass through the cystic duct and cause pancreatitis. We found foci associating with some but not all gallstones. Foci may be a common cause of so-called gallstone pancreatitis. Therefore, the rotational technique confirming foci with gallstones may be required to plan therapy.

Post cholecystecomy initial pancreatitis and recurrent pancreatitis Caused by foci continuing to be formed and expelled from the cystic duct remnant. Presumably foci would be propelled into the CBD by secretions and/or contractions in the cystic duct remant.

ERCP induced pancreatitis

This occur with or without gallstones and post cholecystectomy Prior to ERCP, foci could accumulate in the lumen of the ampulla and/or have been diverted into the pancreatic duct by the pressure gradient from the CBD to the pancreatic duct. There could also be foci obstruction in the ampulla in the same area as the orifice of the pancreatic duct. Catheterization and pressure of injections could force foci into the pancreatic duct system causing ductule obstruction resulting in localized pancreatitis or generalized if in the main duct. Foci in the gallbladder with or without gallstones may be a reason not to perform ERCP. Our incidence in the general population of 7% for these foci is similar to the incidence of ERCP induced pancreatitis. If our findings hold true then rotational gallbladder ultrasound could be done prior to ERCP biliary catheterization in the future.

Pregnancy pancreatitis – Gallbladder foci were seen in pregnancy but none examined had pancreatitis.

Familial and alcohol related pancreatitis - Foci were seen in 25 pediatric patients 2 to 18 years but none had pancreatitis. Could there be a familial tendency to foci formation. It may be that alcohol consumption is common and so are foci.