The rule
The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
Where a placeholder exists, the X must be used in order for the code to be considered a valid code.
How many codes take one
51,378 of the 74,879 billable codes in FY2027 have 7 characters (69%). By first letter: S 31,049, T 9,924, V 4,086, M 1,574. 14,596 billable codes carry the placeholder X after the third character.
508 lines of the Tabular List define a set of 7th characters, and the set applies to every code below that line. The most common sets:
A D S, as at M97
The same characters and meanings are defined at 409 lines.
| 7th | Meaning (NCHS) |
|---|---|
| A | initial encounter |
| D | subsequent encounter |
| S | sequela |
1 2 3 9, as at E08.32
The same characters and meanings are defined at 25 lines.
| 7th | Meaning (NCHS) |
|---|---|
| 1 | right eye |
| 2 | left eye |
| 3 | bilateral |
| 9 | unspecified eye |
A D G K P S, as at S42.27
The same characters and meanings are defined at 18 lines.
| 7th | Meaning (NCHS) |
|---|---|
| A | initial encounter for closed fracture |
| D | subsequent encounter for fracture with routine healing |
| G | subsequent encounter for fracture with delayed healing |
| K | subsequent encounter for fracture with nonunion |
| P | subsequent encounter for fracture with malunion |
| S | sequela |
0 1 2 3 4 5 9, as at O31
The same characters and meanings are defined at 15 lines.
| 7th | Meaning (NCHS) |
|---|---|
| 0 | not applicable or unspecified |
| 1 | fetus 1 |
| 2 | fetus 2 |
| 3 | fetus 3 |
| 4 | fetus 4 |
| 5 | fetus 5 |
| 9 | other fetus |
Reading one
T36.0X1A: category T36, then 4th character 0, 5th character X (the placeholder), 6th character 1, and the 7th character A. Its title: Poisoning by penicillins, accidental (unintentional), initial encounter.
Quotes: ICD-10-CM Official Guidelines for Coding and Reporting FY 2027 (CMS and NCHS), by section. Counts: computed from the NCHS FY2027 files on this site's build.