What is the first action to take for a patient suspected of having septic arthritis?

In cases of suspected septic arthritis, the first action to take is to perform an arthrocentesis, also known as joint aspiration. This procedure is crucial because it allows for the direct analysis of the joint fluid, which can confirm the presence of infection and help to identify the causative organism through culture and sensitivity testing. This information is vital for guiding appropriate antibiotic therapy.

Additionally, performing an arthrocentesis can also provide therapeutic benefits by relieving pressure in the joint, which may reduce pain and improve function. It helps differentiate septic arthritis from other conditions such as inflammatory arthritis or crystal-induced arthritis, thereby guiding further management.

Starting intravenous antibiotics, ordering imaging studies like a CT scan, or administering NSAIDs without first obtaining the joint fluid can delay the diagnosis and potentially worsen the patient's condition if an infection is indeed present. Therefore, the critical and immediate step in managing a patient with suspected septic arthritis is to conduct an arthrocentesis to obtain joint fluid for analysis.