S21.40Unspecified open wound of back wall of thorax with penetration into thoracic cavity

S21.40 is the ICD-10-CM diagnosis code for unspecified open wound of back wall of thorax with penetration into thoracic cavity. It belongs to category S21 (open wound of thorax), block S20-S29 (injuries to the thorax) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

Within S21.4, choose S21.40 (Unspecified open wound of back wall of thorax with penetration into thoracic cavity) only when documentation doesn't support a more specific option: laceration without foreign body of back wall of thorax with penetration into thoracic cavity (S21.41), laceration with foreign body of back wall of thorax with penetration into thoracic cavity (S21.42), puncture wound without foreign body of back wall of thorax with penetration into thoracic cavity (S21.43), puncture wound with foreign body of back wall of thorax with penetration into thoracic cavity (S21.44) and open bite of back wall of thorax with penetration into thoracic cavity (S21.45).

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.