Which position would best demonstrate the rectum filled with barium?

The best position to demonstrate the rectum filled with barium is the lateral position. When a patient is in a lateral position, typically on their side, the gravity allows the barium to uniformly coat the rectal wall and provides an optimal view of the rectum in its entirety. This position helps visualize the rectum as it extends posteriorly and laterally, making it easier to assess any abnormalities or pathologies that may be present.

In the lateral position, the barium can also help delineate the rectal area more clearly, as it aids in separating the rectum from surrounding structures, reducing superimposition. This is particularly advantageous during a rectal examination or study since it improves the accuracy of imaging findings related to the rectum.

Other positions may not provide the same level of clarity or depth for the rectum. For instance, the supine position would not facilitate the proper distribution of barium in the rectal area as effectively. The prone position could also lead to less optimal filling of the rectum, and the sitting position may not allow for even distribution of the contrast material due to the position of gravity acting on the barium. Thus, the lateral position is the most effective choice for demonstrating a rectum filled with b