Rare case of Bouveret syndrome

Abstract

Biliary fistulae are an uncommon manifestation of gallstone disease. Bouveret syndrome, the eponymous name for a gastric outlet obstruction due to impaction of a large gallstone in the duodenum following cholecystoduodenal fistula, is an even rarer subset of biliary-enteric fistula. The pathology of this condition evolves from a gallstone causing pressure necrosis with the stomach or proximal duodenum. This is ultimately decompressed via a cholecystoenteric fistula. The gallstone then becomes impacted at the gastric outlet or proximal duodenum, causing gastric outlet obstruction. Classically, the gastric outlet obstruction causes vomiting with resultant hypochloremic, hypokalemic metabolic alkalosis (which when tested, exhibits paradoxical acidic urine). Our case highlights this unusual condition with a near-textbook electrolyte imbalance. A 67-year-old female presented to a tertiary hospital with a sixday history of intractable post-prandial vomiting associated with reduced bowel function. She had a similar episode of vomiting 6 months prior associated with epigastric pain, which had resolved spontaneously. Her previous medical history was consistent with a diagnosis of biliary colic 30 years before with the patient electing for observation without intervention. She had no other significant past medical or surgical history, and was not on any regular medications. On examination, there was a soft abdomen with nonperitonitic tenderness in the epigastrium. Abdominal auscultation demonstrated reduced bowel sounds and baseline observations were within normal haemodynamic and temperature ranges. Her bloods demonstrated a severe metabolic alkalosis (Table 1), with hyponatremia (sodium 129 mmol/L), hypokalemia (potassium 2.3 mmol/L) and hypochloremia (chloride 79 mmol/L). She was also noted to have an acute kidney injury with a creatinine of 109 umol/L. Her liver function tests were unremarkable except for a mildly elevated bilirubin (25 umol/L). Serum lipase was elevated at 1239 U/L. Inflammatory markers were elevated (WCC 13.2 × 10/L). Initial resuscitation was with intravenous normal saline for electrolyte correction. A plain abdominal X-ray demonstrated an irregular partially rim calcified focus in the right parasagittal midabdomen measuring up to 48 mm and a non-specific bowel gas pattern (Fig. 1). An oral and IV portal phase post-contrast enhanced CT abdomen was performed to further clarify the diagnosis. This demonstrated a large gallstone eroding through the wall of the gallbladder and into the duodenum, with associated pneumobilia, where it was lodged at D2/D3, causing mild gastric and proximal duodenal dilatation (Fig. 2). The gallbladder was thickened and fat stranding was noted around the pancreas.