A 64-year-old man presents with vomiting and colicky abdominal pain for 12 hours. His last bowel movement was 10 hours ago. Normally, he has two to three bowel movements daily. He has no other symptoms. He also reports intermittent episodes of abdominal pain for the last week that spontaneously subsided. There is no history of abdominal trauma. His medical and surgical histories are unremarkable. He is not on any medications, including over-the-counter drugs or supplements. He drinks socially, between 3 to 4 standard drinks per week on average. He does not smoke or use recreational drugs. A full blood count, serum electrolyte assay, liver profile, renal profile, and serum amylase and lipase levels are all normal.