What is in the drink for a ct scan? what does it do?

The drink is: a contrast material that absorbs xrays and therefore is easily identified on CT scan, often dilute barium. It distends the bowel loops, allowing them to be easily identified, and also allowing bowel wall pathology to be identified. Without the contrast, unopacified, collapsed bowel loops can sometimes be mistaken for pathology, and bowel pathology such as wall edema can be easily missed.