A 58-year-old man presents with excruciating upper abdominal pain, nausea, retching, and diaphoresis for around 30 minutes. No other symptoms are present. Further questioning reveals a history of episodic mild upper abdominal pain and cramps for one year. These always resolved spontaneously. He sought medical attention for this around six months ago and was started on proton pump inhibitors. However, his symptoms did not resolve, and he defaulted on follow-up.

His medical and surgical histories are otherwise unremarkable, and he is not on any medications currently. His last routine health screening was around 1 year ago, at which time he tested negative for diabetes mellitus and dyslipidemia. He does not smoke, only drinks socially, and does not use recreational drugs. His family history is unremarkable. A complete blood count, random capillary glucose, serum electrolyte assay, renal profile, liver profile, and serum amylase and lipase levels are all within normal parameters. Serial ECGs are also normal. Bedside ultrasonography shows no features suggestive of gallstones or acute cholecystitis.