Abscess of tendon sheath, unspecified upper arm

This code signifies an infection with pus formation within the synovial sheath surrounding a tendon in the upper arm. This condition typically presents with localized pain, swelling, warmth, and tenderness along the tendon's course, often limiting movement.

Assign this code when documentation specifies an abscess of a tendon sheath in the upper arm, but the laterality (right or left) is not documented or is unknown. This diagnosis is supported by clinical findings consistent with infection and imaging (e.g., ultrasound, MRI) confirming a fluid collection within the tendon sheath.

• Ensure documentation clearly states "abscess" and "tendon sheath" to differentiate from other soft tissue infections.
• Avoid using this code if laterality is specified; instead, select the more specific code for the right (M65.021) or left (M65.022) upper arm.
• Code any associated infectious organism (e.g., Staphylococcus aureus) as an additional diagnosis, if documented.