What is the diagnosis when joint aspiration is performed, but no synovial fluid is aspirated?

From the Guidelines

When a knee joint aspiration yields no fluid, it does not necessarily indicate the absence of infection, and further diagnostic steps should be considered. The absence of fluid, also known as a "dry tap," can occur even in the presence of infection 88. In such cases, it is essential to ensure proper needle placement, potentially using ultrasound guidance, and consider repositioning the needle or attempting aspiration at a different site, such as the suprapatellar pouch or medial approach 1.

If clinical suspicion for infection or effusion remains high despite the initial failure to aspirate fluid, several strategies can be employed. These include using a larger gauge needle (18-20G) or injecting a small amount (1-2 mL) of sterile saline and then re-aspirating to help retrieve diagnostic fluid. The decision to proceed with these techniques should be guided by the patient's clinical presentation and the suspicion of underlying conditions such as infection, inflammatory arthritis, or crystalline arthropathy.

It is also crucial to document the attempted procedure, including the technique used and the absence of aspirated fluid, as this information itself has diagnostic value 1. In cases where symptoms persist and the suspicion of infection is high, despite negative or unsuccessful aspiration, further diagnostic tests such as blood work (e.g., CRP, ESR) and imaging studies (e.g., ultrasound, MRI) may be warranted to guide further management. The combination of clinical judgment, laboratory tests, and imaging can help in making an accurate diagnosis and guiding appropriate treatment, even in the absence of aspirated fluid.

From the Research

Joint Aspiration with No Fluid Aspirated

• Joint aspiration is a procedure used to diagnose and treat joint disease, and it involves removing fluid from the joint space 2, 3, 4.
• The knee is the most common site for joint aspiration, but any non-axial joint can be aspirated 2, 3, 4.
• If no fluid is aspirated during joint aspiration, it may be due to several reasons, such as:
  • The joint space is dry, meaning there is no excess fluid in the joint.
  • The aspiration technique is incorrect, or the needle is not in the correct position.
  • The joint is not inflamed, or there is no synovial fluid present.
• Analysis of synovial fluid is helpful in the differential diagnosis of arthritis and is the definitive method for diagnosis of septic arthritis and crystal arthritis 3, 4.
• However, the provided studies do not specifically address the scenario where no fluid is aspirated during joint aspiration.

Possible Next Steps

• Re-evaluate the joint aspiration technique and ensure that the needle is in the correct position.
• Consider using imaging studies, such as ultrasound or MRI, to guide the aspiration needle and confirm the presence of fluid in the joint.
• If no fluid is still aspirated, consider alternative diagnostic methods, such as blood tests or other imaging studies, to diagnose the underlying condition.

Related Studies

• Studies have shown that intra-articular injections of corticosteroids can provide rapid pain relief and resolution of inflammation in most injected joints 2, 3, 4.
• Other studies have investigated the use of intra-articular non-steroidal anti-inflammatory drug injections for the treatment of osteoarthritis, which may be an alternative therapy for joint pain 5.
• A prospective observational study found that joint aspiration and intra-articular corticosteroid injection can reduce knee pain and improve quadriceps strength in individuals with knee synovitis 6.