Is Q21.16 a billable ICD-10-CM code?

Yes. Q21.16 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does Q21.16 sit in the tabular list?

Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0), in the block Congenital malformations of the circulatory system (Q20-Q28).

What cannot be coded together with Q21.16?

Q21.16 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above Q21.16 (Q21) and apply to it just the same.

Q21.16

Q21.16 — Sinus venosus atrial septal defect, unspecified

Billable / specific codeICD-10-CMPOA exempt

Q21.16 is a billable, specific ICD-10-CM code for sinus venosus atrial septal defect, unspecified. It is valid for submission on a claim.

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

Sinus venosus defect, NOS

Excludes1 inherited from the categories above Q21.16

These are not written on Q21.16, but they bind it: a note on a category applies to every code beneath it. Billing Q21.16 with anything listed here is a denial.

Written on Q21 — Congenital malformations of cardiac septa

acquired cardiac septal defect (I51.0)

Excludes2 inherited from the categories above Q21.16

Also inherited, and the opposite of Excludes1: these conditions are not part of Q21.16, but a patient can have both, so you may code both.

Written on Q21.1 — Atrial septal defect

ostium primum atrial septal defect (type I) (Q21.20)

Risk adjustment

Q21.16 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

Q21.16 is named in 21 Medicare coverage policies — 21 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A52850Billing and Coding: Cardiac Catheterization and Coronary Angiography
A52850Billing and Coding: Cardiac Catheterization and Coronary Angiography
A52868Billing and Coding: Transesophageal Echocardiography (TEE)
A52868Billing and Coding: Transesophageal Echocardiography (TEE)

How Q21.16 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to Q21.16.

Abnormal, abnormality, abnormalities›sinus venosus
Defect, defective›sinus venosus
Defect, defective›atrial septal›sinus venosus

Code history

Q21.16 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Related codes at this level

Codes that share Q21.1. If Q21.16 is not quite right, the correct code is usually one of these.

Questions about Q21.16

Is Q21.16 a billable ICD-10-CM code?: Yes. Q21.16 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does Q21.16 sit in the tabular list?: Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0), in the block Congenital malformations of the circulatory system (Q20-Q28).
What cannot be coded together with Q21.16?: Q21.16 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above Q21.16 (Q21) and apply to it just the same.