In evaluating a child with acute hip pain, which imaging test is a priority?

In the evaluation of a child with acute hip pain, obtaining an anteroposterior (AP) and lateral x-ray of the hip is a priority because it is often the first and most essential imaging study to assess for any acute bony pathology, such as fractures or dislocations. X-rays provide a quick and effective means of visualizing the bone structures, which is crucial in the acute setting.

In children, the differential diagnosis of hip pain can include conditions like septic arthritis, osteomyelitis, or developmental dysplasia, and x-rays can help rule out bony injuries and evaluate alignment issues. Moreover, x-rays are readily available, involve less time than other imaging modalities, and expose the patient to lower levels of radiation compared to CT scans.

While other imaging techniques like ultrasound can also be useful, especially in assessing effusions or fluid collections, they do not provide a comprehensive view of bony anatomy. MRI is valuable for soft tissue assessment and complex cases but is not typically the first step in acute injury evaluation due to its cost, longer duration, and limited availability in emergency settings. Thus, the AP and lateral x-ray remains the priority for initial examination in this context.