ICD-10-CM Guidelines 2024/36
Questions & Answers
Conventions for the ICD-10-CM - -The conventions for the ICD-10-CM are the
general rules for use of the classification independent of the guidelines.
These conventions are incorporated within the Alphabetic Index and Tabular
List of the ICD-10-CM as instructional notes.
-The Alphabetic Index and Tabular List - -The ICD-10-CM is divided into the
Alphabetic Index, an alphabetical list of terms and their corresponding code,
and the Tabular List, a structured list of codes divided into chapters based on
body system or condition. The Alphabetic Index consists of the following
parts: the Index of Diseases and Injury, the Index of External Causes of
Injury, the Table of Neoplasms and the Table of Drugs and Chemicals.
-Format and Structure - -The ICD-10-CM Tabular List contains categories,
subcategories and codes. Characters for categories, subcategories and codes
may be either a letter or a number. All categories are 3 characters. A three-
character category that has no further subdivision is equivalent to a code.
Subcategories are either 4 or 5 characters. Codes may be 3, 4, 5, 6 or 7
characters. That is, each level of subdivision after a category is a
subcategory. The final level of subdivision is a code. Codes that have
applicable 7th characters are still referred to as codes, not subcategories. A
code that has an applicable 7th character is considered invalid without the
7th character. The ICD-10-CM uses an indented format for ease in reference.
-Use of codes for reporting purposes - -For reporting purposes only codes
are permissible, not categories or subcategories, and any applicable 7th
character is required.
-Placeholder character - -The ICD-10-CM utilizes a placeholder character
"X". The "X" is used as a placeholder at certain codes to allow for future
expansion. An example of this is at the poisoning, adverse effect and
underdosing codes, categories T36-T50. Where a placeholder exists, the X
must be used in order for the code to be considered a valid code.
-7th Characters - -Certain ICD-10-CM categories have applicable 7th
characters. The applicable 7th character is required for all codes within the
category, or as the notes in the Tabular List instruct. 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.
, -Abbreviations NEC - -"Not elsewhere classifiable" This abbreviation in the
Alphabetic Index represents "other specified." When a specific code is not
available for a condition, the Alphabetic Index directs the coder to the "other
specified" code in the Tabular List.
-abbreviations NOS - -"Not otherwise specified" This abbreviation is the
equivalent of unspecified.
-Brackets are used in the Tabular List to - -to enclose synonyms, alternative
wording or explanatory phrases. Brackets are used in the Alphabetic Index to
identify manifestation codes.
-Parentheses - -are used in both the Alphabetic Index and Tabular List to
enclose supplementary words that may be present or absent in the
statement of a disease or procedure without affecting the code number to
which it is assigned. The terms within the parentheses are referred to as
nonessential modifiers. The nonessential modifiers in the Alphabetic Index to
Diseases apply to subterms following a main term except when a
nonessential modifier and a subentry are mutually exclusive, the subentry
takes precedence. For example, in the ICD-10-CM Alphabetic Index under the
main term Enteritis, "acute" is a nonessential modifier and "chronic" is a
subentry. In this case, the nonessential modifier "acute" does not apply to
the subentry "chronic".
-Colons - -are used in the Tabular List after an incomplete term which needs
one or more of the modifiers following the colon to make it assignable to a
given category.
-"Other" codes - -Codes titled "other" or "other specified" are for use when
the information in the medical record provides detail for which a specific
code does not exist. Alphabetic Index entries with NEC in the line designate
"other" codes in the Tabular List. These Alphabetic Index entries represent
specific disease entities for which no specific code exists, so the term is
included within an "other" code.
-"Unspecified" codes - -Codes titled "unspecified" are for use when the
information in the medical record is insufficient to assign a more specific
code. For those categories for which an unspecified code is not provided, the
"other specified" code may represent both other and unspecified.
-Includes Notes - -This note appears immediately under a three-character
code title to further define, or give examples of, the content of the category.
-Inclusion terms - -List of terms is included under some codes. These terms
are the conditions for which that code is to be used. The terms may be
synonyms of the code title, or, in the case of "other specified" codes, the
Questions & Answers
Conventions for the ICD-10-CM - -The conventions for the ICD-10-CM are the
general rules for use of the classification independent of the guidelines.
These conventions are incorporated within the Alphabetic Index and Tabular
List of the ICD-10-CM as instructional notes.
-The Alphabetic Index and Tabular List - -The ICD-10-CM is divided into the
Alphabetic Index, an alphabetical list of terms and their corresponding code,
and the Tabular List, a structured list of codes divided into chapters based on
body system or condition. The Alphabetic Index consists of the following
parts: the Index of Diseases and Injury, the Index of External Causes of
Injury, the Table of Neoplasms and the Table of Drugs and Chemicals.
-Format and Structure - -The ICD-10-CM Tabular List contains categories,
subcategories and codes. Characters for categories, subcategories and codes
may be either a letter or a number. All categories are 3 characters. A three-
character category that has no further subdivision is equivalent to a code.
Subcategories are either 4 or 5 characters. Codes may be 3, 4, 5, 6 or 7
characters. That is, each level of subdivision after a category is a
subcategory. The final level of subdivision is a code. Codes that have
applicable 7th characters are still referred to as codes, not subcategories. A
code that has an applicable 7th character is considered invalid without the
7th character. The ICD-10-CM uses an indented format for ease in reference.
-Use of codes for reporting purposes - -For reporting purposes only codes
are permissible, not categories or subcategories, and any applicable 7th
character is required.
-Placeholder character - -The ICD-10-CM utilizes a placeholder character
"X". The "X" is used as a placeholder at certain codes to allow for future
expansion. An example of this is at the poisoning, adverse effect and
underdosing codes, categories T36-T50. Where a placeholder exists, the X
must be used in order for the code to be considered a valid code.
-7th Characters - -Certain ICD-10-CM categories have applicable 7th
characters. The applicable 7th character is required for all codes within the
category, or as the notes in the Tabular List instruct. 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.
, -Abbreviations NEC - -"Not elsewhere classifiable" This abbreviation in the
Alphabetic Index represents "other specified." When a specific code is not
available for a condition, the Alphabetic Index directs the coder to the "other
specified" code in the Tabular List.
-abbreviations NOS - -"Not otherwise specified" This abbreviation is the
equivalent of unspecified.
-Brackets are used in the Tabular List to - -to enclose synonyms, alternative
wording or explanatory phrases. Brackets are used in the Alphabetic Index to
identify manifestation codes.
-Parentheses - -are used in both the Alphabetic Index and Tabular List to
enclose supplementary words that may be present or absent in the
statement of a disease or procedure without affecting the code number to
which it is assigned. The terms within the parentheses are referred to as
nonessential modifiers. The nonessential modifiers in the Alphabetic Index to
Diseases apply to subterms following a main term except when a
nonessential modifier and a subentry are mutually exclusive, the subentry
takes precedence. For example, in the ICD-10-CM Alphabetic Index under the
main term Enteritis, "acute" is a nonessential modifier and "chronic" is a
subentry. In this case, the nonessential modifier "acute" does not apply to
the subentry "chronic".
-Colons - -are used in the Tabular List after an incomplete term which needs
one or more of the modifiers following the colon to make it assignable to a
given category.
-"Other" codes - -Codes titled "other" or "other specified" are for use when
the information in the medical record provides detail for which a specific
code does not exist. Alphabetic Index entries with NEC in the line designate
"other" codes in the Tabular List. These Alphabetic Index entries represent
specific disease entities for which no specific code exists, so the term is
included within an "other" code.
-"Unspecified" codes - -Codes titled "unspecified" are for use when the
information in the medical record is insufficient to assign a more specific
code. For those categories for which an unspecified code is not provided, the
"other specified" code may represent both other and unspecified.
-Includes Notes - -This note appears immediately under a three-character
code title to further define, or give examples of, the content of the category.
-Inclusion terms - -List of terms is included under some codes. These terms
are the conditions for which that code is to be used. The terms may be
synonyms of the code title, or, in the case of "other specified" codes, the
