Final answer:
When hypertonic contrast media are introduced into the intestinal tract, water moves out of the cells into the intestinal lumen due to osmosis, potentially causing cellular dehydration.
Step-by-step explanation:
When higher osmolality contrast media are given for imaging of the intestinal tract, there is a movement of fluid from the cells into the intestinal lumen. This happens because the contrast media create a hypertonic solution in the intestinal tract. As a result, fluid from inside the cells, which are in an area of lower osmolality compared to the hypertonic solution in the intestinal tract, will move towards the area of higher solute concentration via osmosis. This movement of water out of the cells can potentially lead to cellular dehydration if the water is not replaced. In terms of water absorption, typically, the small intestine absorbs approximately 90 percent of the fluid that enters it, driven by osmotic gradients. However, the introduction of a hypertonic contrast medium reverses this gradient, causing water to move from the cells and interstitial fluid into the intestinal lumen.