What imaging study is most appropriate for diagnosing cholecystitis?

Ultrasound of the right upper quadrant (US RUQ) is the most appropriate initial imaging study for diagnosing cholecystitis due to its high sensitivity for detecting gallstones and inflammation of the gallbladder. The ultrasound is a non-invasive procedure that does not involve radiation, making it particularly suitable for evaluating gallbladder conditions, especially in patients who may be pregnant or have other contraindications for CT or MRI.

Ultrasound can visualize gallstones, assess gallbladder wall thickening, and detect pericholecystic fluid, all of which are indicators of acute cholecystitis. It is typically the first-line test because it is readily available, quick to perform, and provides immediate information regarding the state of the gallbladder.

In addition to ultrasound, a CT scan of the abdomen can also be useful, especially in complicated cases, but it is not the first-line imaging due to higher radiation exposure and its reduced specificity for gallbladder issues compared to ultrasound. MRI is not routinely used for the diagnosis of cholecystitis, as it is more time-consuming and expensive, and is better reserved for specific indications such as imaging without radiation. An X-ray is generally not effective for diagnosing cholec