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General Coding Guidelines for ICD-10-CM

General Coding Guidelines for ICD-10-CM - Medical Billers and Coders

ICD-10-CM Basics

Selecting accurate diagnosis codes using ICD-10-CM is challenging due to the availability of more than 68,000 codes. In this blog, we shared general coding guidelines for ICD-10-CM, which will help you select accurate diagnosis codes. Before we proceed with coding guidelines, you’ll need access to two lists in ICD-10 CM: the Alphabetical Index of diagnostic terms and the Tabular List of ICD-10 codes.

The Alphabetical Index of diagnostic terms lists thousands of ‘main terms’ alphabetically. Under each of those main terms, there is often a sub-list of more detailed terms; for instance, ‘Cataract’ has a sub-list of 84 terms. The Tabular List of ICD-10 codes is organized alphanumerically from A00.0 to Z99.89. It is divided into chapters based on body parts or conditions.

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General Coding Guidelines for ICD-10-CM

Locating a code in the ICD-10-CM 

To select a code in the classification corresponding to a diagnosis or reason for a visit documented in a medical record, locate the term in the Alphabetic Index and then verify the code in the Tabular List.

Read and be guided by instructional notations in the Alphabetic Index and the Tabular List. It is essential to use both the Alphabetic Index and Tabular List when locating and assigning a code.

The Alphabetic Index does not always provide the complete code. The entire code, including laterality and any applicable 7th character, can only be selected in the Tabular List.

A dash (-) at the end of an Alphabetic Index entry indicates that additional characters are required. Even if a dash is not included in the Alphabetic Index entry, referring to the Tabular List is necessary to verify that no 7th character is required.

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Level of Detail in Coding 

Diagnosis codes are to be used and reported at the highest number of characters available and to the highest level of specificity documented in the medical record. ICD-10-CM diagnosis codes are composed of 3, 4, 5, 6, or 7 characters.

Codes with three characters are included in ICD-10-CM as the heading of a category of codes that may be further subdivided by using fourth, fifth, or sixth characters, which provide greater detail.

A three-character code will be used only if not further subdivided. If applicable, a code is invalid if it has not been coded to the total number of characters required for that code, including the 7th character.

Multiple Coding for a Single Condition 

In addition to the etiology/manifestation convention that requires two codes to describe a single condition that affects multiple body systems entirely, other single conditions also need more than one code. ‘Use additional code’ notes are found in the Tabular List for codes not part of an etiology/manifestation pair where a secondary code is helpful in fully describing a condition.

The sequencing rule is the same as the etiology/manifestation pair. ‘ Use additional code’ indicates that a secondary code should be added if known. 

Combination Code 

A combination code is a single code used to classify two diagnoses: a diagnosis with an associated secondary process (manifestation) or an associated complication. Combination codes are identified by referring to sub-term entries in the alphabetic index and reading the inclusion and exclusion notes on the tabular list.

Assign only the combination code when that code fully identifies the diagnostic conditions involved or when the Alphabetic Index directs. Multiple coding should not be used when the classification provides a combination code that identifies all the elements documented in the diagnosis.

When the combination code lacks specificity in describing the manifestation or complication, an additional code should be used as a secondary code.

Sequela (Late Effects) 

A sequela is a residual effect (condition produced) after the acute phase of an illness or injury has terminated. There is no time limit on when a sequela code can be used. The residual may be apparent early, such as in cerebral infarction, or it may occur months or years later due to a previous injury.

Examples of sequela include scar formation resulting from a burn, deviated septum due to a nasal fracture, and infertility due to tubal occlusion from old tuberculosis. Coding of sequela generally requires two codes sequenced in the following order: the condition or nature of the sequela is sequenced first. The sequela code is sequenced second.

Use of Sign/Symptom/Unspecified Codes 

Sign/symptom and ‘unspecified’ codes have acceptable, even necessary, uses. While specific diagnosis codes should be reported when supported by the available medical record documentation and clinical knowledge of the patient’s health condition, there are instances when signs/symptoms or unspecified codes are the best choices for accurately reflecting the healthcare encounter. Each healthcare encounter should be coded to the level of certainty known for that encounter. 

Impending or Threatened Condition 

Code any condition described at the time of discharge as ‘impending’ or ‘threatened’ as follows: 

  • If it did occur, code it as the confirmed diagnosis. 
  • If it did not occur, reference the Alphabetic Index to determine if the condition has a subentry term for ‘impending’ or ‘threatened’ and also reference primary term entries for “Impending” and ‘Threatened.’
  • If the sub-terms are listed, assign the given code. 
  • If the sub-terms are not listed, code the existing underlying condition(s), not the condition described as impending or threatened.

Remaining Coding Guidelines for ICD-10-CM

Here are some additional important guidelines to keep in mind when coding with ICD-10-CM:

  • The appropriate codes from A00.0 through T88.9, Z00-Z99.8, and U00-U85 must be used to identify diagnoses, symptoms, conditions, problems, complaints, or other reason(s) for the encounter/visit.
  • Codes that describe symptoms and signs, as opposed to diagnoses, are acceptable for reporting purposes when the provider has not established a related definitive diagnosis.
  • Signs and symptoms associated routinely with a disease process should not be assigned as additional codes unless otherwise instructed by the classification.
  • Additional signs and symptoms that may not be associated routinely with a disease process should be coded when present.
  • If the same condition is described as acute (sub-acute) and chronic, and separate subentries exist in the Alphabetic Index at the same indentation level, code both and sequence the acute (sub-acute) code first.
  • Each unique ICD-10-CM diagnosis code may be reported only once for an encounter. This applies to bilateral conditions when no distinct codes identify the same ICD-10-CM diagnosis code classifies laterality or two different situations.
  • Some ICD-10-CM codes indicate laterality, specifying whether the condition occurs on the left, right, or is bilateral. If no bilateral code is provided and the condition is bilateral, assign separate codes for both the left and right sides. If the side is not identified in the medical record, assign the code for the unspecified side.
  • If the provider documents a ‘borderline’ diagnosis at the time of discharge, the diagnosis is coded as confirmed unless the classification provides a specific entry (e.g., borderline diabetes). If a borderline condition has a particular index entry in ICD-10-CM, it should be coded as such. Since borderline conditions are not uncertain diagnoses, no distinction is made between the care setting (inpatient versus outpatient). 

Medical Billers and Coders (MBC) is a leading medical billing company that provides complete billing and coding services. For provider education purposes, we shared general coding guidelines for ICD-10-CM. The following link provides a detailed explanation.

In case any assistance is needed for medical billing and coding, contact us at 888-357-3226 / info@medicalbillersandcoders.com

FAQs

1. What is ICD-10-CM?

ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification) is a system healthcare providers use to classify and code all diagnoses, symptoms, and procedures recorded in conjunction with hospital care.

2. How do I use the Alphabetical Index and Tabular List in ICD-10-CM?

First, locate the diagnostic term in the Alphabetical Index to select a code. After identifying the code, verify it in the Tabular List, which organizes codes by body systems and conditions. This ensures you assign the correct and complete code.

3. What is the importance of laterality in ICD-10-CM coding?

Laterality specifies whether a condition affects the body’s left, right, or both sides. If a code for laterality is not specified, you must assign separate codes for each side or use an “unspecified” code if the documentation lacks details.

4. What is a combination code in ICD-10-CM?

A combination code classifies two diagnoses: a diagnosis with a secondary manifestation or a diagnosis with a complication. It should be used when it fully identifies the condition. If not, additional codes may be required.

5. Can multiple codes be used for a single condition in ICD-10-CM?

Yes, some conditions may require multiple codes to describe the diagnosis and its effects fully. This often happens with conditions that affect various body systems, where ‘use additional code’ notes in the Tabular List guide the selection of secondary codes.

6. What is meant by “sequela” in ICD-10-CM coding?

Sequela refers to a residual condition resulting from a previous illness or injury. Two codes are typically required in coding: one for the current condition and another for the sequela.

7. How detailed should ICD-10-CM coding be?

Diagnosis codes should be reported with as many characters as available to achieve the highest specificity. Codes may contain 3 to 7 characters, with three-character codes acting as general categories unless further details are available.

8. When should unspecified or symptom codes be used in ICD-10-CM?

Unspecified or symptom codes should be used when the diagnosis is not confirmed, or the medical record lacks sufficient information to assign a more specific code. These codes are acceptable when necessary to accurately reflect the healthcare encounter.

9. What should I do if a condition is described as “impending” or “threatened”?

If the condition occurred, code it as a confirmed diagnosis. If it did not, use the Alphabetic Index to determine if “impending” or “threatened” terms have specific codes. If no code is available, document the underlying condition instead.

10. How can Medical Billers and Coders (MBC) assist with ICD-10-CM coding?

MBC provides comprehensive medical billing and coding services, including assistance with ICD-10-CM coding and ensuring compliance with coding guidelines. For more information, contact MBC at 888-357-3226 or info@medicalbillersandcoders.com.

Reference: ICD-10-CM Official Guidelines for Coding and Reporting FY 2023
ICD-10 CM Copyright @World Health Organization (WHO) 

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