Rupture of popliteal cyst

This code describes the acute rupture of a Baker's cyst, a fluid-filled sac located behind the knee. The rupture typically results in the sudden leakage of synovial fluid into the surrounding calf tissues, causing pain and swelling.

Apply this code when documentation clearly indicates a ruptured popliteal cyst as the primary diagnosis. This often presents with acute calf pain, swelling, and ecchymosis, mimicking deep vein thrombosis. Supporting documentation includes imaging (e.g., ultrasound) confirming the rupture or a physician's clinical diagnosis based on characteristic symptoms.

• Differentiate from other causes of calf pain and swelling; ensure the documentation specifies "rupture."
• Do not confuse with an unruptured popliteal cyst (M71.2).
• Consider sequencing if an underlying condition (e.g., osteoarthritis, rheumatoid arthritis) is the cause of the popliteal cyst.