Which position is effective in placing a negative contrast agent in the fundus of the stomach during a double contrast upper GI exam?

The right anterior oblique (RAO) position is effective for placing a negative contrast agent, such as air or gas, in the fundus of the stomach during a double contrast upper GI exam. This positioning allows gravity to facilitate the distribution of the negative contrast agent throughout the stomach, particularly into the fundus, which is the uppermost portion of the stomach.

In the RAO position, the anatomy is ideal for viewing the gastric fundus while ensuring that the negative contrast can rise and outline that area more clearly. This position helps to separate the gastric contents for better visualization and detail in imaging, which is critical during a double contrast study.

The other positions, while they may provide varying visualizations of the anatomy, do not achieve the same effectiveness for specific access to the fundus as the RAO does. The supine position generally keeps the stomach in a more neutral position, and the prone position may compress the fundus due to gravity. The left anterior oblique (LAO) may move the fundus away from the area of interest rather than promoting optimal filling with the negative contrast. Thus, the RAO position is superior for this particular purpose in a double contrast upper GI exam.