Does probe frequency influence diagnostic accuracy in newborn hip ultrasound?

Ultrasonography of the hip has gained wide acceptance as reliable method for diagnosing developmental hip dysplasia in infants. This blinded study was conducted to investigate the influence of two linear probes with different frequency on diagnostic accuracy and reproducibility. In 206 consecutive newborns, the bony roof angle (α-angle) and cartilage roof angle (β-angle) were assessed by three investigators according to Graf. The hips were measured twice both with a 7.5 MHz and a 12 MHz linear transducer (Sonoline G60S(®) ultrasound system; Siemens, Erlangen, Germany). Each investigator evaluated his sonograms 6 weeks later. Depending on the mean values for α-angle and β-angle, the hips were classified. Reproducibility of the Graf classification was not found to be influenced. In two of three investigators, we observed significant improvement concerning variation of the β-angle with the 12 MHz probe. The use of high-resolution transmitters may improve diagnostic accuracy in ultrasonography of the newborn's hip.