A 45-year-old man presents with severe constant epigastric pain radiating to the back, with vomiting. Serum amylase is over three times the upper limit of normal. What is the most likely diagnosis?

Answer: E. Acute pancreatitis

Acute pancreatitis

Severe, constant epigastric pain radiating to the back with vomiting, plus a serum amylase over three times the upper limit of normal, is diagnostic of acute pancreatitis - glandular autodigestion provoking an acute inflammatory response.

Diagnostic criteria

• Clinical: severe epigastric pain radiating to the back, vomiting, and systemic signs of shock in severe cases.
• Biochemical: serum amylase > 3x upper limit of normal (or > 1000 IU), or a raised serum lipase.
• Radiological: contrast-enhanced CT where the diagnosis is in doubt or with delayed presentation.

Why not the alternatives

• Biliary colic is colicky and self-limiting; cholecystitis has a positive Murphy's sign; a perforated ulcer causes generalised peritonitis; an MI causes chest pain with ECG changes (though amylase can rise modestly in other conditions, > 3x ULN with this picture indicates pancreatitis).