What Is a Manifestation Code in Medical Coding?

In medical coding, accuracy is crucial for proper diagnosis reporting, insurance reimbursement, and compliance. One specific type of diagnosis code that often confuses new coders is the manifestation code. Understanding what these codes represent—and how to use them correctly—is essential for coding integrity.

Definition of a Manifestation Code

A manifestation code describes the sign or symptom of an underlying disease or condition. It is not the primary diagnosis but rather a secondary code that explains the clinical consequences of another condition.

In other words, the manifestation code “manifests” the effect of the root cause.

For example:

• E11.36 – Type 2 diabetes mellitus with diabetic cataract

  • E11.36 (diabetic cataract) is a manifestation of Type 2 diabetes mellitus.

  • The underlying cause—diabetes—must be coded first, followed by the manifestation code.

Key Characteristics of Manifestation Codes

• Always secondary – They cannot be used as the principal diagnosis.

• Require a code for the underlying cause – This is known as “code first” instruction in ICD-10-CM.

• Often identified by instructional notes such as “Code first underlying disease” or “Use additional code to identify…” in the Tabular List.

• Frequently appear in the ICD-10-CM with phrases like “in diseases classified elsewhere”.

Coding Guidelines for Manifestation Codes

1. Code the underlying condition first – This establishes the primary reason for the patient’s care.

2. Assign the manifestation code second – This explains the clinical expression or complication of the disease.

3. Follow ICD-10-CM instructions – The Tabular List will guide the correct sequencing with specific notes.

4. Do not code symptoms separately – If the manifestation code fully describes the condition, avoid adding duplicate symptom codes.

Example:
Patient has Parkinson’s disease with dementia.

• G20.A1 – Parkinson’s disease with dyskinesia

• F02.80 – Dementia in other diseases classified elsewhere, unspecified severity

  • Here, F02.80 is the manifestation code, sequenced after Parkinson’s disease.

Why Correct Use Matters

• Compliance – Improper sequencing can result in claim denials and compliance violations.

• Data Accuracy – Public health data relies on correct primary and manifestation coding for research and statistics.

• Reimbursement – Accurate sequencing ensures proper DRG assignment and payment.

Tips for Coders

• Always check for “code first” notes in the ICD-10-CM Tabular List.

• Familiarize yourself with conditions that have common manifestations (e.g., diabetes, infections, neurological disorders).

• Use the Alphabetic Index to locate the underlying condition and then verify both codes in the Tabular List.

• Remember: manifestation codes are never standalone—they complete the coding picture.

ICD-10 conventions https://codingclarified.com/icd-10-cm-coding-conventions/

Manifestation ICD-10-CM Codes

The following 422 ICD-10-CM codes describe the manifestation of an underlying disease, not the disease itself.

https://www.icd10data.com/ICD10CM/Codes/Rules/Manifestation_Codes#google_vignette

Coding Clarified signs & symptoms https://codingclarified.com/medical-coding-signs-symptoms-in-diseases/