What is the investigation of choice in CBD obstruction?

The investigation of choice in cases of CBD (common bile duct) obstruction is typically an endoscopic retrograde cholangiopancreatography (ERCP). This procedure allows for both diagnostic imaging and therapeutic intervention, such as stone removal or stent placement. Alternatively, magnetic resonance cholangiopancreatography (MRCP) can be used as a non-invasive imaging option. However, ERCP remains the gold standard due to its ability to address the obstruction directly.