ICD-10-CM subcategories can contain how many characters?

ICD-10-CM subcategories are designed to provide detailed specificity in coding diagnoses. They can indeed contain four, five, or six characters. The structure begins with a three-character category code, followed by an additional character that extends the detail regarding the condition. Further, a subcategory may have additional characters that refine the specificity even more, leading to a total of four to six characters.

The format begins with a letter followed by two numbers, and then additional characters can be alphanumeric. Thus, the correct choice recognizes the flexible length of subcategories, which vary based on the complexity and specificity of the diagnosis being coded. This allows for a comprehensive representation of medical conditions, aligning with the goals of detailed documentation and correct reimbursement practices.