Intermittent hydrarthrosis, right knee

This code signifies recurrent, self-limiting episodes of joint swelling in the right knee due to an accumulation of synovial fluid, without an identifiable underlying cause such as trauma or infection. It represents a rare, chronic inflammatory condition characterized by intermittent effusions.

Apply this code when documentation explicitly states "intermittent hydrarthrosis" affecting the right knee. Supporting documentation should describe episodic, non-traumatic swelling of the right knee joint, often resolving spontaneously. This diagnosis is typically made after ruling out other causes of knee effusion.

• Ensure the laterality (right knee) is clearly documented; do not use for bilateral or unspecified knee involvement.
• Distinguish from other forms of hydrarthrosis with known causes (e.g., traumatic, infectious, or associated with specific arthropathies).
• Code any underlying or associated conditions separately if documented, but only if they are not the direct cause of the intermittent hydrarthrosis.