Final answer:
During an intraoperative evaluation of the common bile duct, a contrast dye is typically used as part of an Endoscopic retrograde cholangiopancreatography (ERCP); this allows the visualization of biliary structures on an X-ray.
Step-by-step explanation:
The medication that might be used during an intraoperative evaluation of a patient's common bile duct, such as in the case of Mr. Robertson, usually involves the injection of a dye. This procedure is likely to be an Endoscopic retrograde cholangiopancreatography (ERCP), which is a technique that uses a tube placed down the throat and into the small intestine. Once the tube is correctly positioned, a dye is injected to help visualize the structure of the common bile duct, other bile ducts, and the pancreatic duct on an X-ray.
In some cases, if an obstruction or a complication is suspected, other medications may be administered to manage symptoms or to treat any infection that may have caused the symptoms. However, the primary substance used during the procedure to evaluate the bile duct intraoperatively is most commonly a contrast dye.