Rheumatoid arthritis without rheumatoid factor, right knee

This code identifies a chronic autoimmune inflammatory condition primarily affecting the synovial lining of the right knee joint, characterized by the absence of rheumatoid factor in diagnostic testing. It signifies a seronegative form of rheumatoid arthritis, leading to pain, swelling, stiffness, and potential joint destruction in the specified articulation.

Apply this code when documentation confirms a diagnosis of rheumatoid arthritis, specifically noting seronegative status (rheumatoid factor negative) and the primary affected joint as the right knee. This is appropriate for initial diagnoses, exacerbations, or ongoing management of seronegative RA impacting this specific joint. Supporting documentation includes physician notes, lab results confirming seronegative status, and imaging reports detailing right knee involvement.

• Ensure documentation explicitly states "rheumatoid factor negative" or "seronegative" to differentiate from seropositive forms.
• Verify laterality (right knee) is clearly documented; do not assume if not specified.
• Consider sequencing this code as the primary diagnosis when the right knee is the focus of the encounter, followed by codes for any associated manifestations or complications.