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ICD-10 Code Structure | MicroMD


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ICD-10 Codes

What is defined in an ICD-10 code?

ICD-10 codes allow doctors to specifically define diseases, signs, symptoms, abnormal findings, complaints, social circumstances, and external causes of injuries and diseases. There is a heightened level of specificity to ICD-10 which is reached through detailed documentation.

What is ICD-10’s code structure?

In ICD-10-CM (Clinical Modification), the codes structure is as follows:

The code is 3-7 characters long. The first character is an alpha character (other than “U”). The second character is numeric. These two first characters together describe the code’s category. Characters 3-7 can be any combination of alpha or numeric characters. They describe the etiology, anatomical site, and severity of the codes, while character 7 serves as an extension code, if needed. A decimal is placed after the third character.

For ICD-10-PCS (Procedure Coding System), the code structure is as follows:

The code is 7 alphanumeric characters long. The first character identifies the section or type of procedure. The second character identifies the body system or anatomical region the procedure is taking place in. The third character identifies the root operation or objective of the procedure. Character four identifies the body part or specific anatomical site of the procedure. Character five identifies the approach or technique used during the procedure. The sixth character identifies any devices left at the operative site, and character seven identifies qualifiers for any additional information. As not all procedures involve leaving devices at the operative site and there will not always be additional information, characters six and seven can be filled in with a Z. There are no decimals in ICD-10-PCS codes.



Doesn’t identify right versus left.

Identifies right versus left >40% of codes.

Codes are 3-5 digits

  • First digit is alpha (E or V) or numeric
  • Digits 2-5 are numeric
  • Decimal is placed after the third character

7 digits

  • Digit 1 is alpha; Digit 2 is numeric
  • Digits 3-7 are alpha or numeric
  • Decimal is placed after third character

No placeholder characters

“X” placeholders

14,000 codes

69,000 codes to better capture specificity

Limited Severity Parameters

Extensive Severity Parameters

Limited Combination Codes

Extensive Combination Codes to better capture complexity

1 type of Excludes Notes

2 types of Excludes Notes

Limited available space for new codes

Flexibility to add new codes

Ambiguous overall detail embedded within codes

Very specific detail embedded within codes (Allows description of comorbidities, manifestations, etiology/causation, complications, detailed anatomical location, sequelae, degree of functional impairment, biologic and chemical agents, phase/stage, lymph node involvement, lateralization and localization, procedure or implant related, age related, or joint involvement)

Sample code: 813.15, Open fracture of head of radius

Sample code: S52123C, Displaced fracture of head of unspecified radius, initial encounter for open fracture type IIIA, IIIB, or IIIC

Sources: ICD-10 Implementation Guide for Small and Medium Practices & Road to 10

ICD-9 Procedure Codes


3-4 numbers in length

7 alpha-numeric characters in length

Approximately 3,000 codes

Approximately 87,000 available codes

Based on outdated technology

Reflects current usage of medical terminology and devices

Limited space for adding new codes

Flexible for adding new codes

Lacks detail

Very specific

Lacks laterality

Has laterality

Generic terms for body parts

Detailed descriptions for body parts

Lacks descriptions of methodology and approach for procedures

Provides detailed descriptions of methodology and approach for procedures

Lacks precision to adequately define procedures

Precisely defines procedures with detail regarding body part, approach, any device used, and qualifying information

Source: American Medical Association