An Anterior-Posterior (AP) Pelvis X-ray is a standard, front-facing medical image of your pelvic bones, hip joints, and upper thigh bones. The term "AP" means the X-ray beam enters through the front (anterior) of your body and exits through the back (posterior) while you lie flat on your back. It is the most common starting scan doctors use to check the health and alignment of your entire pelvic structure.