Pediatric hip effusions: Evaluation with power Doppler sonography

PURPOSE: To determine if power Doppler sonography allows differentiation of infectious from noninfectious hip effusions and thereby obviates joint aspiration. MATERIALS AND METHODS: Twenty-nine consecutive children (30 hips) with sonographically identified hip effusion were prospectively evaluated with power Doppler sonography. Both hips were evaluated in each patient by using identical imaging parameters and were then compared. Medical charts were reviewed to determine the eventual diagnosis. RESULTS: At power Doppler sonography, none of 16 patients with transient synovitis had increased flow in the affected hip compared with the contralateral normal hip. Of 11 patients with septic arthritis, one had asymmetric increased flow, and two others, in whom contralateral comparison images were limited, had probable increased flow. Three patients with miscellaneous diagnoses had asymmetric normal flow. CONCLUSION: Because power Doppler sonograms did not depict increased flow in most patients with septic arthritis, normal flow on power Doppler sonograms does not allow exclusion of septic arthritis and should not preclude aspiration when clinically warranted.