Final answer:
In an esophagus study looking for a perforation, a water-soluble contrast is used over barium sulfate to avoid complications should the contrast medium leak into surrounding tissues.
Step-by-step explanation:
For a patient undergoing an esophagus study to look for a perforation in fluoroscopy, a water-soluble contrast is typically used instead of barium sulfate. Barium sulfate is commonly used in medical imaging for various gastrointestinal studies because it provides good detail on X-ray images. However, in cases where a perforation of the esophagus is suspected, barium can pose a risk if it leaks into the surrounding tissues or mediastinum. Therefore, a water-soluble contrast medium, which is less irritating to surrounding tissues and can be absorbed by the body, would likely be the preferred choice for this procedure to minimize the potential risk of complications should a perforation be present.