Coding Process and Diagnosis Rules
This is the most important step in assigning a diagnosis code during a medical encounter.
What is choosing the main term that describes the reason for the visit?
Coders should always begin code selection in this part of the ICD-10-CM book.
What is the Alphabetic Index?
These letters mean a code applies even when specific details are not available.
What are NOS and NEC?
This note means two conditions cannot be coded together.
What is Excludes1?
ICD-10-CM codes can have this many characters at most.
What is 7 characters?
In outpatient settings, coders should not assign codes for diagnoses labeled as these.
What are "rule out," "probable," "suspected," or "questionable" diagnoses?
This part of the book must always be used to verify the code and ensure all rules are followed.
What is the Tabular List?
This symbol [ ] in the Index signals that the code inside can only be used as a secondary code.
What are brackets indicating manifestation codes?
This instruction tells you to code the underlying condition first.
What is “Code first”?
A code with fewer characters than required is this.
What is invalid?
These codes are assigned only when no diagnosis is made and symptoms are all that's known.
What are symptom codes (Chapter 18)?
These vertical marks in the Alphabetic Index help identify the level of subterm indentation.
What are shaded vertical guidelines?
This letter is used as a placeholder when a code needs a 7th character but is missing a 4th–6th character.
What is “X”?
This note tells you to assign an additional code to give a complete picture of the condition.
What is “Use additional code”?
The first 3 characters of an ICD-10 code represent this.
What is the category?
This type of diagnosis can be reported in inpatient settings if documented at discharge, even if it’s not confirmed.
What is an uncertain diagnosis?
These instructional terms in the Index or Tabular list refer you to another location to find a code.
What are "See" or "See also" references?
Parentheses in code descriptions include these types of terms.
What are nonessential modifiers?
This abbreviation (NEC) tells the coder there’s no more specific code available for the documented condition.
What is “Not Elsewhere Classified”?
This is required for certain injury codes to reflect encounter type (e.g., initial, subsequent, sequela).
What is the 7th character?
These codes from Chapter 21 are used when the reason for a visit is something other than a disease or injury.
What are Z codes (Factors Influencing Health Status)?
This is the process of picking a code from the Index, verifying it in the Tabular List, and checking for character completion.
What is locating and confirming a code?
Codes using the word “and” actually mean this.
What is “and/or”?
These two subterms signal a causal link between conditions and should be coded together unless documentation says otherwise.
What are “with” and “due to”?
Placeholder characters and added digits must be verified here before assigning the final code.
What is the Tabular List?