Sequence ICD-10-CM Codes for Proper Payment
Five terms lead the way to determining primary diagnosis codes.
When we select diagnosis codes for billing, we are telling the story of a patient’s healthcare encounter. Patients often present with multiple conditions — some related, some not. Medical coders are tasked with selecting the most specific codes and putting them in the right order. This code arrangement is called “sequencing,” and it is an essential step to correct coding.
This article focuses on identifying when you need to report additional diagnosis codes and determining their proper order. If you are unsure of what to look for as you’re trying to determine the right codes and sequencing, the following terms referenced in the ICD-10-CM Official Guidelines for Coding and Reporting will point you in the right direction:
In Diseases Classified Elsewhere
First things first: Why is the patient asking to be seen? The reason for the visit drives code sequencing. This is generally the “first-listed diagnosis.” Once the first-listed diagnosis is established, it may be followed by other coexisting conditions. Sometimes the first-listed diagnosis will be pointed out by the conventions with a “code first” note.
In diseases classified elsewhere:
- Referenced in the Official Guidelines at I.A.13. The convention instructs you to code “in diseases classified elsewhere” codes second to the etiologic condition.
- Etiologic conditions are usually listed under the code.
Example 1: Primary stomach cancer of the fundus with dermatomyositis
C16.1 Malignant neoplasm of fundus of stomach
When you look up this code in the Tabular List of the ICD-10-CM code book, you’ll find that this category has the instructional note “Use additional code to identify alcohol abuse and dependence.”
M36.0 Dermato(poly)myositis in neoplastic disease
When you look up this code in the Tabular List, you’ll find the instructional note “Code first underlying neoplasm (C00-D49).”
Example 2: Parkinson’s disease with dementia, without behavioral disturbance
G20 Parkinson’s disease
F02.80 Dementia in other diseases classified elsewhere without behavioral disturbance
When you look up this code in the Tabular List, you’ll find the instructional note to “Code first” the underlying physiological condition.
Sequela (Late Effects)
A sequela condition is one that results from a previous disease or injury.
- Coding for a late effect usually requires two codes.
- Sequencing comes directly from the Official Guidelines at I.B.10.
Example: Keloid scar as a late effect of third-degree burn to the chest wall
L91.0 Hypertrophic scar
T21.31XS Burn of third degree of chest wall, sequela
Use Additional Code
This convention instructs you to “Code first” the underlying condition, followed by etiology and/or manifestations.
- Appears in the Official Guidelines at I.A.13.
- The “Use additional” code note is found below the underlying condition code.
Example: Type 2 diabetes with stage three chronic kidney disease
E11.22 Type 2 diabetes mellitus with diabetic chronic kidney disease
When you look up this code in the Tabular List, you’ll find the instructional “Use additional code” note to identify the stage of chronic kidney disease (N18.1-N18.6).
N18.3 Chronic kidney disease, stage 3 (moderate)
When you look up this code in the Tabular List, you’ll find the instructional “Use additional code” note to identify kidney transplant status (Z94.0), if applicable.
This convention instructs that two codes may be required, but it does not provide sequencing direction.
- Appears in the Official Guidelines at I.A.17.
- The circumstances of the encounter will determine the sequencing.
Example 1: Secondary pulmonary arterial hypertension in HIV (reason for the encounter is for HIV)
B20 Human immunodeficiency virus [HIV] disease
I27.21 Secondary pulmonary arterial hypertension (code also code)
When you look up this code in the Tabular List, you’ll find the instructional note to “Code also” associated conditions, if applicable, or adverse effects of drugs or toxins.
Example 2: Conn’s syndrome with right adrenal adenoma
D35.01 Benign neoplasm of right adrenal gland (code also code)
When you look up this code in the Tabular List, you’ll find the instructional note to “Use additional code” to identify any functional activity (this determines the order).
E26.01 Conn’s syndrome
When you look up this code in the Tabular List, you’ll find an instructional note to “Code also” adrenal adenoma (D35.0-).
This type of punctuation appears in both the Alphabetic Index and Tabular List.
- Appears in the Official Guidelines at I.A.7. Codes that are in brackets in the Alphabetic Index are always sequenced second.
- Brackets are used in the Tabular List to enclose synonyms, alternative words, or explanatory phrases.
Example: Exanthema epidemic with meningitis – Alphabetic Index entry A88.0 [G02]
A88.0 Enteroviral exanthematous fever [Boston exanthem]
G02 Meningitis in other infectious and parasitic diseases classified elsewhere
When you look up this code in the Tabular List, you’ll find an instructional note to “Code first” any underlying disease.
Coding tip: Remember to follow the ICD-10-CM Official Guidelines for Coding and Reporting for the current year as you encounter different coding scenarios, and that the conventions of the classification take precedence over the guidelines. The guidelines are based on the coding and sequencing instructions in the ICD-10-CM code book.
ICD-10-CM Official Guidelines for Coding and Reporting FY2020
AMA, ICD-10-CM 2020 The Complete Official Codebook
AMA, Principles of ICD-10-CM Coding