Basics of Diagnosis Coding

Diagnosis coding is the process of translating narrative medical description into a code.

CMS Coding and Reporting Guidelines for diagnosis coding:

• Use the ICD-9-CM codes that describe the patient's diagnosis, symptom, complaint, condition, or problem.
• Use the ICD-9-CM code that is chiefly responsible for the item or service provided.
• Assign codes to the highest level of specificity. Use the fourth and fifth digits when indicated as necessary in your ICD-9-CM volumes.
• Do not code suspected diagnoses in the outpatient setting. Code only the diagnosis symptom, complaint, condition, or problem reported. Medical records, not claim forms, should reflect that the services were provided for "rule out" purposes.
• Code a chronic condition as often as applicable to the patient's treatment.
• Code all documented conditions which coexist at the time of the visit that require or affect patient care or treatment. (Do not code conditions which no longer exist)

ICD-9 Conventions:

Non specific codes

Decimal digits .8 and .9 indicate “other specified” or “non otherwise specified.”  Use only when more specific information is not available, or doesn’t exist, not just “when it is not convenient to get more detailed information.”

NEC (Not elsewhere classified) Used in Volumes 1 and 2

These codes should only be used when a coder lacks precise information necessary to code a term more specifically.

NOS (Not otherwise specified) Used in Volume 1

Etiology codes have "use additional code" notes to indicate when manifestation codes are required and manifestation codes have "code first" notes to indicate when an etiology code is required.

The words "in diseases classified elsewhere" are part of the code title for most ?manifestation codes.

See: Indicates the coder should look up the term specified to find the correct code.

See Also:  Indicates the coder should look up the term specified to find the correct code.

The ICD-9-CM book consists of three volumes.  We use the first two:

Volume 1: Tabular list of Diseases and Injuries

    * Use this volume to select codes

    * Arranged in numerical sequence

    * Contains V codes and E codes

Volume 2 is an Alphabetic Index to Volume 1 and includes:

    *  Alphabetic Index of Diseases and Injuries

    * Table of Drugs and Chemicals

    * Index of External Causes of Injuries and Poisonings

Always begin the initial search for a code with Volume 2, but do not code directly from Volume 2. Coding from Volume 2 can lead to inaccurate codes because:

    *  Not all fifth digits are indicated

    * Include, Exclude, and Notes are not included

V codes are for screening personal history of or family history of.  You are most likely to use them for patients who no longer have active disease or for whom you are doing a screening service. 

E codes are for accidents or incidents, like these.  Motor vehicle accidents are in the range of E-810 to 819; accidental poisonings, E-850 to E-858, and many others. 

    * Code to the highest degree of specificity.  When fourth and fifth digits are available, they must be used.

    * Code the diagnosis, symptom, complaint, condition that is chiefly responsible for the visit

    * If the diagnosis is not known, use symptoms

    * Do not code rule out, probable or possible, use symptoms

    * Code underlying and chronic conditions only if they were considered and documented in today’s visit

    * For multiple injuries: code the most severe first.

    * Limit use of unspecified codes when more specific codes are available and there is definitive information available.

    * For inpatient services, code the reason that lead to admission, then secondary diagnoses.

    * Use acute and chronic conditions when ICD-9 uses those distinctions.

Remember, physician claims are paid based on CPT® code, but denied based on diagnosis code!

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