Usefulness of Ultrasound in the diagnosis of Septic Arthritis: about a case

Introduction. Septic arthritis in the pediatric age group is a medical emergency with serious consequences if not treated early. Early diagnosis is essential to initiate appropriate treatment and prevent permanent joint damage. Ultrasound has emerged as an essential tool for the early and accurate detection of septic arthritis, allowing for a rapid and detailed evaluation of the affected joint, especially in cases where clinical findings are subtle. Clinical Case. A 1-month-old male infant was brought by his mother to the emergency service of our hospital due to irritability and crying when changing his diaper, significant increase in the volume of the right thigh, and pain during movement. An initial ultrasound was performed, which reported signs of superficial cellulitis, and a second ultrasound was performed, which revealed thickening of the synovium, a fluid collection in the joint capsule with echoes inside it, which concluded with the diagnosis of septic arthritis of the right hip. Discussion. Ultrasound not only allowed the identification of joint effusion and synovial thickening, but was also crucial in differentiating between superficial infection (cellulitis) and deeper septic arthritis. Conclusions. The importance of our clinical case lies in the use of ultrasound as a diagnostic method to detect joint involvement early. In combination with the clinical method and microbiological studies, it becomes an important component of the diagnostic approach and timely management of septic arthritis, thus reducing associated complications.