Sphincter of Oddi dysfunction that could not be diagnosed with Rome IV: a case report.

A 30-year-old female patient presented with monthly episodes of severe intermittent upper abdominal pain, especially after consuming fatty meals. Over a period of 5 years, she visited the emergency department 21 times due to the intensity of the pain. Although the pain appeared consistent with biliary pain, both blood and imaging tests showed no abnormalities. Despite not meeting the Rome IV criteria, we suspected sphincter of Oddi dysfunction (SOD). To further investigate, we conducted hepatobiliary scintigraphy (HBS), which revealed a clear delay in bile excretion. With the patient's informed consent, we performed endoscopic sphincterotomy (EST) and as of 10 months later, there have been no recurrences. This case demonstrates an instance of SOD that could not be diagnosed using the Rome IV criteria alone but was successfully identified through HBS. It underscores the possibility of hidden cases of SOD among patients who regularly experience severe epigastric pain, where routine blood or imaging tests may not provide a diagnosis. HBS may be a useful non-invasive test in confirming the presence of previously undiagnosed SOD. As SOD can be easily treated with EST, updating the current diagnostic criteria to include such types of SOD should be considered in the future.