What imaging technique is often the first step in investigating suspected gallstone disease?

The abdominal ultrasound is typically the first step in investigating suspected gallstone disease due to its effectiveness in visualizing the gallbladder and the presence of gallstones. This imaging modality is non-invasive, does not involve radiation, and provides real-time images, allowing clinicians to assess the size, number, and possible complications associated with gallstones, such as inflammation or obstruction.

Ultrasound is particularly adept at detecting gallstones as they appear as echogenic (bright) structures with posterior acoustic shadowing. Additionally, abdominal ultrasound can evaluate other related conditions like cholecystitis, which can be associated with gallstones.

Other imaging techniques may be used for further evaluation or in specific circumstances, but they are typically not the first choice. For instance, a CT scan might be used in cases where complications are suspected or detailed imaging of adjacent organs is necessary, but it involves radiation exposure and is not as readily available in all settings. X-rays are not particularly useful for detecting gallstones because they are often radiolucent. MRCP is a specialized MRI technique that provides detailed images of the biliary and pancreatic ducts and might be used later if there is a suspicion of complications or other conditions but is not typically the first-line investigation.