U.S. ICD-10-CM · FY 2027

Q21 ICD-10-CM Code: Congenital malformations of cardiac septa

A clear reference for the official code description, hierarchy, and related coding information from the FY 2027 U.S. release.

Code definition

Official description

Q21

Congenital malformations of cardiac septa

ICD-10-CM diagnosis code · United States clinical modification

Classification

Where Q21 sits

  1. 1

    Chapter 17

    Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1)

  2. 2

    Section

    Congenital malformations of the circulatory system (Q20-Q28)

  3. 3

    Category Q21

    Congenital malformations of cardiac septa

  4. 4

    Code Q21

    Congenital malformations of cardiac septa

More specific choices

Codes under Q21

Q21 is a non-billable category. Choose the child code that best matches the documented diagnosis.

Documentation details

Notes for this code

Inclusion terms

No inclusion terms are listed for Q21.

Code first

No “code first” instruction is listed for Q21.

Use additional code

No “use additional code” instruction is listed for Q21.

Excludes1

Conditions that should not be reported together with this code.

  • acquired cardiac septal defect (I51.0)

Excludes2

Conditions not included here that may be reported separately when present.

No Excludes2 note is listed for Q21.

Transparency

Source and release

Data release

U.S. ICD-10-CM · FY 2027

Effective date

Oct 1, 2026

This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.

Review the CDC/NCHS ICD-10-CM source

Code-specific guidance

Frequently asked questions

What does ICD-10-CM code Q21 mean?

Q21 is the FY 2027 U.S. ICD-10-CM code for “Congenital malformations of cardiac septa.”

Is Q21 a billable or specific ICD-10-CM code?

No. Q21 has more specific child codes in the FY 2027 reference data. Select the code that matches the documentation and confirm the active code set and payer requirements.

Where is Q21 located in ICD-10-CM?

Q21 is listed in Chapter 17, Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1), within Congenital malformations of the circulatory system (Q20-Q28) (Q20–Q28), under category Q21, Congenital malformations of cardiac septa.

What coding notes are listed for Q21?

No inclusion terms are listed for Q21 in this reference record. No code-first instruction is listed. Excludes1 notes: acquired cardiac septal defect (I51.0). No Excludes2 note is listed.

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