ICD-10-CM › S00-T88 › S00-S09 › S04.2 Injury of trochlear nerve › S04.21

S04.21

Injury of trochlear nerve, right side

Not billableICD-10-CM diagnosis code.

This code exists but cannot be submitted on its own. It groups the more specific codes beneath it.

A category header for its whole life, FY2016 onwards. It has never been valid for submission on its own.

Submit one of these 3 more specific codes instead:

  • S04.21XA Injury of trochlear nerve, right side, initial encounter
  • S04.21XD Injury of trochlear nerve, right side, subsequent encounter
  • S04.21XS Injury of trochlear nerve, right side, sequela

This code requires a seventh character. See the rule below.

What has happened to this code

Every change the publisher made, from 2014 to now. Entries marked draft are from the pre-implementation releases: ICD-10 took effect on 1 October 2015, so nothing before FY2016 was ever valid on a claim.

  1. FY2014 Added to the draft code set draft Injury of trochlear nerve, right side

Official coding rules

Published by CDC for FY2027. A rule attached to a category binds every code beneath it, so the rules inherited from this code's ancestors are shown with the code they come from.

Inherited from S04 Injury of cranial nerve

Seventh character required

  • The appropriate 7th character is to be added to each code from category S04

Code first

  • any associated intracranial injury (S06.-)

Code also

  • any associated:
  • open wound of head (S01.-)
  • skull fracture (S02.-)

Also known as

  • The selection of side should be based on the side of the body being affected

Inherited from the S00-S09 section Injuries to the head (S00-S09)

Excludes2 - not included here

  • burns and corrosions (T20-T32)
  • effects of foreign body in ear (T16)
  • effects of foreign body in larynx (T17.3)
  • effects of foreign body in mouth NOS (T18.0)
  • effects of foreign body in nose (T17.0-T17.1)
  • effects of foreign body in pharynx (T17.2)
  • effects of foreign body on external eye (T15.-)
  • frostbite (T33-T34)
  • insect bite or sting, venomous (T63.4)

Code also

  • for any associated infection

Includes

  • injuries of ear
  • injuries of eye
  • injuries of face [any part]
  • injuries of gum
  • injuries of jaw
  • injuries of oral cavity
  • injuries of palate
  • injuries of periocular area
  • injuries of scalp
  • injuries of temporomandibular joint area
  • injuries of tongue
  • injuries of tooth

How CDC's index refers to this code

Wording from the official alphabetic index. Much of it appears nowhere in the code description, which is why a search for the everyday phrase so often finds nothing.

Codes in the same group

CodeDescriptionStatus
S04.20 Injury of trochlear nerve, unspecified side Not billable
S04.22 Injury of trochlear nerve, left side Not billable