Paediatricsmiddle twist
A 4-year-old girl has refused to walk since yesterday and cries whenever her right leg is moved. Temperature is 38.9 degrees Celsius and heart rate 148 per minute, with a blood pressure of 96/62 mmHg and warm peripheries. She lies with the right hip flexed and externally rotated and resists any internal rotation. C-reactive protein is 96 mg/L (less than 5) and the white cell count is 19.4 x10^9/L (5.0 to 15.0). Intravenous access has been obtained, blood cultures taken and analgesia given. Which one of the following should be arranged next for this girl?