In a child with suspected septic arthritis of the hip, which finding helps confirm infection on ultrasound?

In a child with suspected septic arthritis of the hip, which finding helps confirm infection on ultrasound?

• A. Fever
• B. Ultrasound-confirmed effusion
• C. Inability to bear weight
• D. Elevated CRP/ESR

Answer: (B)

The key idea is that seeing fluid inside the joint on ultrasound directly supports a joint infection in a child with suspected septic arthritis and guides further steps. An ultrasound-detected joint effusion indicates there is intra-articular material that can be aspirated for diagnostic tests, such as Gram stain and culture, which helps confirm infection. Fever, inability to bear weight, and elevated CRP/ESR are helpful clues to inflammation or infection but do not visualize the joint itself or provide direct confirmation on imaging. Therefore, ultrasound-confirmed effusion is the best choice because it shows the presence of intra-articular fluid that enables definitive sampling and diagnosis.

The key idea is that seeing fluid inside the joint on ultrasound directly supports a joint infection in a child with suspected septic arthritis and guides further steps. An ultrasound-detected joint effusion indicates there is intra-articular material that can be aspirated for diagnostic tests, such as Gram stain and culture, which helps confirm infection. Fever, inability to bear weight, and elevated CRP/ESR are helpful clues to inflammation or infection but do not visualize the joint itself or provide direct confirmation on imaging. Therefore, ultrasound-confirmed effusion is the best choice because it shows the presence of intra-articular fluid that enables definitive sampling and diagnosis.