Transient synovitis, unspecified ankle and foot

This code signifies a temporary, non-infectious inflammation of the synovial membrane within an unspecified ankle or foot joint. It is characterized by acute joint pain and swelling without evidence of trauma, infection, or chronic arthropathy. The condition typically resolves spontaneously within a few weeks.

Apply this code when documentation indicates transient synovitis affecting an ankle or foot, and the specific laterality (right or left) is not specified. This diagnosis is often made after ruling out other causes of acute joint pain, such as fracture, sprain, or septic arthritis. Supporting documentation would include clinical notes describing acute onset of pain, swelling, and limited range of motion, with imaging studies (if performed) showing no significant structural damage.

• Do not use this code if the laterality of the affected ankle or foot is documented; instead, select a more specific code (M67.371, M67.372).
• Ensure documentation explicitly states "transient synovitis" or a similar temporary inflammatory process, rather than a chronic or infectious condition.
• Consider sequencing this code as the primary diagnosis when it is the reason for the encounter, especially if other conditions are ruled out.