American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the diagnostic test of choice for Lyme Arthritis?

1. Joint aspiration

2. Serologic testing for Borrelia burgdorferi

3. Computed tomography scan

4. Magnetic resonance imaging

The correct answer is: Serologic testing for Borrelia burgdorferi

The diagnostic test of choice for Lyme arthritis is serologic testing for Borrelia burgdorferi. Lyme disease is caused by the bacterium Borrelia burgdorferi, which is transmitted through tick bites, and serologic testing is essential for confirming the diagnosis. This type of testing detects antibodies against the bacterium in the patient’s blood, indicating that they have been exposed to the pathogen and may have developed Lyme disease. In the context of Lyme arthritis, serologic tests can help differentiate it from other forms of arthritis, providing a clear link to the underlying infectious cause. The recommended screening tests are enzyme-linked immunosorbent assays (ELISA) followed by confirmatory tests such as Western blot if the initial test is positive or inconclusive. This is crucial because Lyme arthritis typically involves a specific clinical picture and laboratory confirmation, allowing for appropriate treatment with antibiotics. While joint aspiration can be useful in assessing joint inflammation or ruling out other conditions, it does not confirm the presence of Lyme disease itself. Imaging studies like computed tomography scans or magnetic resonance imaging are not definitive diagnostic tools for Lyme arthritis, as they may provide information about the condition of the joints but do not offer evidence of the Borrelia infection. Thus, serologic testing stands