Updated October 2026 for FY2027. The examples reflect the FY2027 ICD-10-CM code set and Official Guidelines (Section I.A.13), effective October 1, 2026.
A manifestation code reports a condition caused by an underlying disease, such as dementia due to Parkinson’s disease. ICD-10-CM requires the underlying disease (the etiology) to be coded first and the manifestation second, and manifestation codes titled “in diseases classified elsewhere” can never be the principal or first listed diagnosis. The Tabular List flags these pairs with a “use additional code” note at the etiology code and a “code first” note at the manifestation code.
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What Is a Manifestation Code in Medical Coding?
Some conditions have an underlying cause that produces effects in one or more body systems. ICD-10-CM calls the cause the etiology and the effect the manifestation. The Official Guidelines (Section I.A.13, the etiology/manifestation convention) require the etiology to be sequenced first, followed by the manifestation.
How do you recognize a manifestation code?
- “In diseases classified elsewhere” in the code title. Most manifestation codes carry this phrase. These codes are never permitted as the first listed or principal diagnosis.
- A “code first” note under the manifestation code, telling you to report the underlying condition first.
- A “use additional code” note under the etiology code, telling you to add the manifestation.
- Codes in brackets in the Alphabetic Index. When the Index lists two codes together, the code in brackets is the manifestation and is always sequenced second.
Some manifestation codes do not include “in diseases classified elsewhere” in the title. For those, the “use additional code” and “code first” notes still set the order.
What are examples of manifestation codes?
Dementia in Parkinson’s disease
The Official Guidelines use this pair as their example. Parkinson’s disease is coded first from category G20, then dementia from category F02. For example, Parkinson’s disease without dyskinesia or fluctuations with dementia, unspecified severity, without behavioral disturbance:
- G20.A1: Parkinson’s disease without dyskinesia, without mention of fluctuations
- F02.80: Dementia in other diseases classified elsewhere, unspecified severity, without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety
Dementia in Alzheimer’s disease
- G30.9: Alzheimer’s disease, unspecified (etiology, coded first)
- F02.80: Dementia in other diseases classified elsewhere (manifestation, coded second)
What is the difference between a manifestation code and a combination code?
A manifestation pair takes two codes. A combination code describes the cause and the effect in a single code. Many diabetes complications work this way: E11.36, Type 2 diabetes mellitus with diabetic cataract, already includes both the diabetes and the cataract, so no separate manifestation code is needed. Always check the Tabular List, because the classification decides whether one code or two are required. See our guide to ICD-10 combination codes.
How do you sequence a manifestation code?
- Locate the condition in the Alphabetic Index and note any code in brackets.
- Verify both codes in the Tabular List and read the “code first” and “use additional code” notes.
- Report the etiology first and the manifestation second.
- Do not add separate codes for symptoms that are integral to the coded conditions.
Why does manifestation code sequencing matter?
Putting a manifestation code first causes claim edits and denials, and on inpatient claims it can change the MS-DRG. Correct sequencing also keeps public health and quality data accurate. Learn more in our guide to ICD-10-CM coding conventions.
Related guides: Medical Coding Sequela and the Medical Coding Reference Library.
Manifestation Code FAQs
Can a manifestation code be the principal diagnosis?
No. Codes titled “in diseases classified elsewhere” are never permitted as the principal or first listed diagnosis. They must follow the code for the underlying condition.
What is the difference between etiology and manifestation?
The etiology is the underlying disease. The manifestation is the condition it causes in a body system. The etiology is coded first.
How do I find manifestation codes in the Alphabetic Index?
The Index lists the etiology code first and the manifestation code in brackets. The bracketed code is always sequenced second.
Is E11.36 a manifestation code?
No. E11.36 is a combination code that includes both type 2 diabetes and the diabetic cataract.
What does a “code first” note mean?
It tells you the code you are looking at is a manifestation and the underlying condition must be reported before it.
Does every dementia code require an etiology code first?
No. Category F02 (dementia in other diseases classified elsewhere) is a manifestation and needs the underlying condition first, such as G30.9 or G20.A1. Category F03 (unspecified dementia) is not a manifestation code and can be reported on its own.
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