Sphincter of Oddi dysfunction is a complex and poorly understood syndrome that usually manifests as pain of apparently biliary or pancreatic origin in the absence of an organic cause after conventional investigations. Transduodenal sphincteroplasty with transampullary septectomy (TDS/TAS) is a therapeutic option.¹ Although biliary manometry is the gold standard diagnostic test, the morphine–prostigmine provocation (Nardi) test is sometimes used to screen patients. A fourfold increase in either serum amylase or lipase and reproduction of pain after intramuscular injection of 10 mg morphine (to induce sphincteric spasm) and 1 mg prostigmine (to stimulate pancreatic exocrine secretions) is considered a positive test.^2,3 However, the enzymatic changes may also occur in healthy subjects and in patients with irritable bowel syndrome,^3,4 bringing the clinical value of the test into question. Conversely, when the Nardi test was carried out on 70 patients with chronic abdominal pain, enzyme elevation was detected in only 23 patients (33%), 16 (70%) of whom had ampullary stenosis.⁵

We undertook these studies to characterise the response to the Nardi test in 20 healthy young adult subjects and 24 patients with sphincter of …