If RUQ ultrasound is unclear for cholecystitis, what is the next best step?

• A. ERCP
• B. CT scan
• C. HIDA scan
• D. Endoscopic ultrasound

Answer: (C)

When a right upper quadrant ultrasound is inconclusive for cholecystitis, the most appropriate next step is to perform a HIDA scan. A HIDA scan, or Hepatobiliary Iminodiacetic Acid scan, is a nuclear imaging technique that evaluates the function of the gallbladder and can provide confirmation of cholecystitis. It specifically assesses the gallbladder's ability to concentrate the radioactive tracer; if the gallbladder does not visualize on the scan, it indicates cholecystitis due to a blockage, often caused by gallstones.

In situations where the ultrasound does not provide clear answers, the HIDA scan's ability to assess gallbladder function makes it a valuable tool in establishing a definitive diagnosis. Other imaging modalities, while also useful in certain contexts, do not directly assess gallbladder function in the same way. For example, a CT scan may provide additional anatomical detail or identify complications but does not specifically evaluate gallbladder activity. The decision not to proceed with ERCP or endoscopic ultrasound further aligns with established diagnostic pathways for suspected cholecystitis, as these techniques are not the first line for diagnosing gallbladder inflammation directly.

The HIDA scan offers a targeted approach to address