In simple words: This code refers to a follow-up visit for a specified injury to the vein behind the knee, which is not a simple cut or tear. The injured leg (right or left) isn't specified in this code.

This code describes an injury to the popliteal vein, which is located at the back of the knee. The injury is specified as "other," meaning it's not a simple laceration or tear. The affected leg is unspecified (right or left), and this is a subsequent encounter, meaning it's not the initial visit for this injury.

Example 1: A patient was previously treated for a popliteal vein injury, unspecified leg, due to a deep laceration in the back of the knee. They return for a follow-up appointment to check on healing and ensure blood flow is not compromised. , A patient who experienced a posterior knee dislocation some weeks ago now presents with persistent pain and swelling behind their knee. After imaging studies, a follow-up visit confirms the presence of a popliteal vein injury as a consequence of the earlier dislocation., Following a sporting accident, a patient received treatment for an injury to the popliteal vein area. They now present for a scheduled follow-up evaluation to monitor the healing process.

The medical record should document the specific type of injury to the popliteal vein, the location (even if unspecified as to laterality), and that this is not the initial encounter for this injury. It should also include details of the initial injury and any subsequent treatments. 

** For accurate coding, it is crucial to determine whether the leg is specified, because specific codes exist for right and left leg injuries (S85.591- and S85.592-, respectively). If laterality is known, the unspecified code (S85.599-) should not be used. This code should only be used for subsequent encounters related to the injury, after the initial encounter is documented with the appropriate "A" code.