P2.F108: Evaluation of the Use of Ultrasounds in the Diagnosis of Developmental Dysplasia of the Hip in Premature Newborns

Background: Hip ultrasound (US) is the gold standard for diagnosing developmental dysplasia of the hip (DDH). Breech infants are 3.75 times more likely than non-breech infants to develop DDH. However, studies show that while DDH occurs in up to 25% in term breech infants, the risk in preterm breech infants is much lower (9% of infants born < 37 weeks and 2% of infants born < 32 weeks). Current guidelines do not address the role of US screening for DDH in premature infants, which may not be an ideal utilization of resources. We sought to determine if there is any benefit to performing routine screening hip US in preterm breech neonates born < 37 weeks and if there is a specific gestational age (GA) category at which breech presentation increases the risk of developing DDH.

Methods: This is a retrospective chart review of 301 infants born breech at < 37 weeks between January 2013 and December 2021 who were admitted to the Cooper University Hospital NICU. We excluded infants that did not survive until discharge or until the first hip US follow-up appointment. Demographic data, DDH risk factors, results of DDH screenings on physical exam and US were collected. Descriptive analysis was completed.

Results: Our population had a mean GA of 28.7 weeks and mean birth weight of 1162 g. Of the 301 preterm breech infants, there was only one case of DDH, correlating with an incidence of 0.3%. This infant had positive findings of DDH on physical exam and on US at 44-46 weeks corrected GA and was born at 29 weeks. Out of 155 breech preterm newborns born at < 29 weeks, there were no patients who had positive findings for DDH on physical exam or on US. Any patient who had a positive finding on physical exam had a positive diagnosis of DDH on US; any patient who had a negative finding on physical exam had a negative diagnosis of DDH on US.

Conclusion: Despite the presence of known DDH risk factors in our population, the incidence in preterm breech newborns was 0.3%, much lower than the reported incidence in term breech newborns at risk for DDH. Of infants born < 29 weeks, there were no infants who had a positive diagnosis of DDH on physical exam or on US. Universal US screening of preterm breech infants born < 29 weeks may not be necessary due to the significantly lower prevalence of DDH in this population, especially in the absence of positive findings for DDH on prior physical exams.