Prevalence of Hip Joint Effusion in Children Diagnosed With Transient Synovitis in the Pediatric Emergency Department

Background: Transient synovitis (TS) is a benign condition characterized by acute hip pain and is a common cause of limping in children. Ultrasonography (US) examination frequently reveals hip joint effusion. However, accurate documentation of its prevalence among children with a diagnosis of TS is scarcely documented in the literature. Objectives: The main objective of our study was to evaluate the prevalence of hip joint effusion among children diagnosed with TS in the pediatric emergency department (PED). Methods: A Retrospective chart review of children diagnosed with TS in the PED between 2017 and 2021 who underwent an US examination as part of their evaluation. Results: Overall, 392 children with a mean age of 5 years were included in the study group, of whom hip effusion was demonstrated in 302 (77%) patients. Most participants underwent point-of-care ultrasound (POCUS) performed by the PED physician as part of their evaluation (328, 83%). Children with hip joint effusion had higher pain levels, hip joint tenderness, and higher CRP values compared with children without an effusion. Conclusions: In our study, the prevalence of hip joint effusion among children presenting to the PED with a final clinical diagnosis of TS was 77%. Higher pain levels and hip joint tenderness were associated with the presence of hip effusion in TS.