CAMRT Radiography Practice Exam

What happens to air in the colon when a patient changes from a supine to a prone position during CT colonography?

1. It remains in the transverse colon

2. It shifts to the descending colon

3. It moves into the ascending colon

4. It is expelled from the body

The correct answer is: It shifts to the descending colon

When a patient changes from a supine to a prone position during CT colonography, the behavior of air in the colon is influenced by gravity and the anatomy of the gastrointestinal tract. In the supine position, air tends to accumulate in the most anterior parts of the colon, which is typically the transverse colon. As the patient shifts to a prone position, gravity causes the air to move toward the lower parts of the colon. The descending colon, being located posteriorly and inferiorly in relation to the transverse colon, becomes a more likely area for the air to accumulate instead. The air moves downwards and fills the descending colon due to the gravitational effects on the gas in an upright position. This transition is significant for proper imaging and visualization of the colon during CT colonography, as it can affect the diagnostic quality of the study. In this context, the movement of air is influenced by the anatomical layout of the colon and the particular positional change, leading to the conclusion that the air shifts to the descending colon.