Diagnostic accuracy of point-of-care ultrasound (PoCUS) for the diagnosis of hip effusion in the pediatric emergency department.

Purpose: A new limp or refusal to weight-bear are common symptoms in children presenting to the pediatric emergency department (ED). This poses a diagnostic challenge, particularly among toddlers and nonverbal patients. Point-of-care ultrasound (PoCUS) used by pediatric emergency medicine physicians may detect hip effusion, which dramatically aids diagnostic workup and management. There is limited literature regarding the accuracy of hip PoCUS conducted by pediatric emergency medicine physicians. This study aims to assess the diagnostic performance of pediatric emergency medicine physician-performed PoCUS in identifying hip effusion.

Methods: This prospective study was conducted in a single-center pediatric ED. Children presenting with limb pain or new limp were evaluated by pediatric emergency medicine physicians who also performed hip PoCUS and categorized findings as either "effusion" or "no effusion" based on standard sonographic definitions. Patients also underwent radiology department ultrasound reviewed by a pediatric radiologist. Diagnostic test characteristics with corresponding 95% confidence intervals (CI) were calculated using radiology department ultrasound findings as the reference standard.

Results: A total of 95 patients were enrolled by 8 pediatric emergency medicine physicians. Excellent agreement was observed between PoCUS performed by pediatric emergency medicine physicians and radiology department ultrasound for the presence or absence of hip effusion (kappa = 0.81 [95% CI 0.70-0.93]). Hip effusion was identified by PoCUS in 44 out of 49 effusion-positive patients, with a sensitivity of 89.8% (95% CI 77.7-96.6%), specificity of 91.3% (95% CI 79.2%-97.5%), positive likelihood ratio of 10.33 (95% CI 4.03-26.47), and negative likelihood ratio of 0.11 (95% CI 0.05-0.26).

Conclusion: PoCUS performed by pediatric emergency medicine physicians has reasonably high sensitivity and specificity for diagnosing hip effusion among pediatric patients presenting to the pediatric ED with a limp or leg pain. This practice may potentially expedite both diagnosis and treatment within this patient population.