CAMRT Radiography Practice Exam

Which projection best demonstrates ascites in a patient who cannot stand or sit erect?

1. Left lateral decubitus

2. Dorsal decubitus

3. AP supine

4. AP supine chest

The correct answer is: Left lateral decubitus

The left lateral decubitus projection is the best choice for demonstrating ascites in a patient who is unable to stand or sit erect. This positioning allows for the detection of free fluid within the abdominal cavity, as the fluid will naturally gravitate to the most dependent area when the patient is lying on their side. When the patient is positioned in the left lateral decubitus, any free fluid will typically collect in the right side of the abdomen, which can then be visualized on the radiograph. This technique is particularly important in the imaging of ascites because the presence of free fluid is best identified when the beam is perpendicular to the fluid level, thereby enhancing the visibility of the fluid's outline on the image. The left lateral position also aids in the differentiation between ascitic fluid and other structures within the abdomen. Other options like dorsal decubitus or AP supine do not provide the same quality of visualization for free fluid. An AP supine view may not clearly show the fluid levels due to the absence of the horizontal beam that would be produced in a decubitus position. Additionally, an AP supine chest would primarily focus on the thoracic area, further making it unsuitable for assessing abdominal conditions such as ascites. Thus, the left