Gallstones Misbehaving

• Gallstone ileus: A gallstone that erodes through a biliary-enteric fistula and gets imapcted in the terminal ileum, causing obstruction. Occurs in 15% of patients with a biliary-enteric fistula.
• Mirizzi syndrome: Gallstone impacted in the cystic duct results in extrinsic compression and obstruction of the extrahepatic bile duct. The cystic duct is usually oriented parallel to the extrahepatic bile duct. CT, ultrasound, or MRI shows a calculus at the junction of the cystic duct and extrahepatic bile duct in conjunction with a dilated bile duct proximal to and a normal-caliber duct distal to the calculus.
• Bouveret syndrome: Biliary-enteric fistula allows a gallstone to enter the duodenum. Gastric outlet obstruction may occur due to impaction of the gallstone in the distal stomach or proximal duodenum. Occurs most commonly in elderly women.
• Dropped calculi: Gallstone spillage is fairly common during laparoscopic cholecystectomy (up to 30%). Abscess formation is relatively rare (< 3%), with the calculus serving as the nidus for infection days to years after cholecystectomy. Patients will usually develop recurrent abscesses until the calculus is removed (drainage and antibiotics by themselves are not effective). Calculi may be found anywhere in the peritoneal or even pleural cavity. Dropped calculi may mimic peritoneal metastases and metastatic ovarian cancer. Invasion through the abdominal wall or across tissue planes with fibrosis and draining sinuses can be seen with actinomycosis, and may mimic a malignant process.

References

• Brennan GB, Rosenberg RD, Arora S. Bouveret syndrome. Radiographics. 2004 Jul-Aug;24(4):1171-5.
• Gayer G, Petrovitch I, Jeffrey RB. Foreign Objects Encountered in the Abdominal Cavity at CT. Radiographics. 2011 Mar-Apr;31(2):409-28.
• Turner MA, Fulcher AS. The cystic duct: normal anatomy and disease processes. Radiographics. 2001 Jan-Feb;21(1):3-22;
• Vyas JM, Kasmar A, Chang HR, Holden J, Hohmann E. Abdominal abscesses due to actinomycosis after laparoscopic cholecystectomy: case reports and review. Clin Infect Dis. 2007 Jan 15;44(2):e1-4.