Which imaging modality is preferred for the evaluation of a suspected biliary obstruction?

Ultrasound is the preferred imaging modality for the evaluation of suspected biliary obstruction due to its effectiveness in visualizing the biliary tree and detecting any obstructions or abnormalities. It is a non-invasive, readily available, and does not involve ionizing radiation, making it safer for patients.

In patients with suspected biliary obstruction, ultrasound can quickly demonstrate the presence of gallstones, dilated bile ducts, and any signs of cholecystitis. It provides real-time imaging and helps in assessing the gallbladder and surrounding structures, which is essential in diagnosing conditions like choledocholithiasis or pancreatitis that may be associated with biliary obstruction.

While other imaging modalities can also be useful in diagnosing biliary obstruction, they have limitations. For instance, a CT scan can provide detailed anatomical information and is excellent for complications; however, it does involve radiation exposure and may not be as sensitive as ultrasound in detecting small stones. X-rays typically do not provide adequate visualization of biliary structures. MRI, particularly MRCP, can be very useful but is generally less accessible and may be reserved for more complex cases after initial ultrasound evaluation.