What is indicated if the diagnosis of cholecystitis from an ultrasound is unclear?

• A. Magnetic resonance imaging (MRI)
• B. Endoscopic retrograde cholangiopancreatography (ERCP)
• C. HIDA scan
• D. Laparoscopy

Answer: (C)

When the diagnosis of cholecystitis is unclear based on ultrasound findings, a HIDA scan, or hepatobiliary iminodiacetic acid scan, is indicated to provide additional information. This nuclear medicine imaging technique evaluates the function of the gallbladder and can confirm the diagnosis of cholecystitis by determining whether the gallbladder is visualized on the scan. If the gallbladder does not take up the radioactive tracer, it may suggest inflammation or obstruction, consistent with cholecystitis.

In unclear cases, the HIDA scan can effectively differentiate between acute cholecystitis and other conditions that may present similarly, as well as assess gallbladder function. This makes it a valuable diagnostic tool in situations where ultrasound is inconclusive.

Other modalities, such as MRI or ERCP, may not be as specifically useful in confirming or ruling out cholecystitis due to their focus on alternative parameters or conditions. Laparoscopy is typically reserved for therapeutic intervention, such as gallbladder removal, and is not primarily used as a diagnostic tool when non-invasive methods, like the HIDA scan, are available.