S20.421A Blister (nonthermal) of right back wall of thorax, initial encounter

Billable ICD-10-CM code, FY2026.

Built from S20.421 with 7th character A (initial encounter).

Applies from S20 Superficial injury of thorax

7th character note

• The appropriate 7th character is to be added to each code from category S20

7th character required

• A — initial encounter
• D — subsequent encounter
• S — sequela

Nearby codes

• S20.419A Abrasion of unspecified back wall of thorax, initial encounter
• S20.419D Abrasion of unspecified back wall of thorax, subsequent encounter
• S20.419S Abrasion of unspecified back wall of thorax, sequela
• S20.42 Blister (nonthermal) of back wall of thorax
• S20.421 Blister (nonthermal) of right back wall of thorax
• S20.421A Blister (nonthermal) of right back wall of thorax, initial encounter (this code)
• S20.421D Blister (nonthermal) of right back wall of thorax, subsequent encounter
• S20.421S Blister (nonthermal) of right back wall of thorax, sequela
• S20.422 Blister (nonthermal) of left back wall of thorax
• S20.422A Blister (nonthermal) of left back wall of thorax, initial encounter
• S20.422D Blister (nonthermal) of left back wall of thorax, subsequent encounter