CAMRT Radiography Practice Exam

What degree of rotation should a patient be placed during an AP pelvis exam to correct the obturator foramen discrepancy?

1. Left rotation

2. Right rotation

3. No rotation required

4. Any degree of rotation

The correct answer is: Right rotation

For an AP pelvis examination, the goal is to visualize the pelvis and the hip joints with minimal distortion. The obturator foramen is the bony hole formed by the pubis and ischium bones, and ideally, the shape of the obturator foramen should be nearly symmetrical on both sides to ensure an accurate assessment. When there is a discrepancy in the appearance of the obturator foramen, it often indicates that the pelvis is not positioned correctly in relation to the X-ray beam. Specifically, if one obturator foramen appears larger or more oval than the other, slight rotation of the patient's body is necessary to correct the alignment. In this case, applying a right rotation moves the patient's left side closer to the imaging plate. This adjustment helps achieve a more symmetrical view of the pelvis, thereby allowing for the obturator foramina to appear more equal in size and shape. Achieving this symmetry is crucial for accurate diagnosis, as it can affect the assessment of pelvic fractures, degeneration, or other pathological conditions. Correctly orienting the patient's pelvis with a right rotation not only aligns the obturator foramina but also helps in visualizing the ilia and sacrum, further enhancing the overall diagnostic capacity of the imaging.