We have undertaken routine ultrasound screening for neonatal hip instability in Coventry since June 1989. Of the 14 050 babies scanned during the first three years, 847 (6%) had ultrasound abnormalities. A grading system, based on the percentage of femoral head coverage, is presented. The proportion of abnormal hips decreased gradually so that by nine weeks, 90% had normal ultrasound appearances. Abnormality was more common in babies with a family history of CDH and in breech presentations. All babies with clinically abnormal hips had an abnormal first ultrasound examination. Five babies not diagnosed by clinical examination and with no risk factors had abnormal ultrasound appearances and were subsequently found to have clinically abnormal hips. Routine ultrasound screening has detected cases which would otherwise have presented late.

Of 4,617 babies born in Coventry in 1986, a total of 448 (9.7%) had either clinical abnormality of the hip or at risk factors for CDH. All were examined by ultrasound, but only 17 required treatment (3.7 per 1,000); in five of these no clinical abnormality had been detected. An additional 81 babies had ultrasound abnormalities but did not require treatment, despite the fact that ultrasound at first showed major hip displacement in 17 of them. Three late cases of CDH have presented among the babies born in 1986, but not examined by ultrasound. This incidence of late CDH is unchanged compared with the previous nine years, although ultrasound had detected covert displacement in a number of hips.