Character X Used as a Placeholder | Diagnosis Coding: Using the ICD-10-CM

ICD-10-CM uses a character X as a placeholder in certain codes to:

Allow for future expansion
Fill in other empty characters when a code less than 6 characters in length needs a 7th character

If a placeholder exists, you must use X for the code to be considered valid.

This chart shows 2 examples of using character X as a placeholder.

Table 6. Examples of ICD-10-CM codes using the character X
ICD-10-CM Code	Description
T46.1X5A	Adverse effect of calcium-channel blockers, initial encounter
T15.02XD	Foreign body in cornea, left eye, subsequent encounter