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Q21.8

Q21.8Other congenital malformations of cardiac septa

Billable / specific codeICD-10-CMPOA exempt

Q21.8 is a billable, specific ICD-10-CM code for other congenital malformations of cardiac septa. It is valid for submission on a claim.

Code also

Both codes may be needed to describe the encounter fully. Sequencing depends on the reason for the visit.

  • , if applicable:
  • Eisenmenger's complex (I27.83)
  • Eisenmenger's syndrome (I27.83)

Inclusion terms

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

  • Eisenmenger's defect
  • Pentalogy of Fallot

Risk adjustment

Q21.8 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

Q21.8 is named in 17 Medicare coverage policies 17 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
  • A54111Billing and Coding: Speech Language Pathology (SLP) Services: Communication Disorders
  • A56451Billing and Coding: Cardiac Computed Tomography (CCT) and Coronary Computed Tomography Angiography (CCTA)
  • A56476Billing and Coding: Cardiac Radionuclide Imaging

How Q21.8 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 Q21.8.

  • Bulbus cordis(left ventricle) (persistent)
  • Pentalogy of Fallot
  • Anomaly, anomalousEisenmenger's(ventricular septal defect)
  • Defect, defectiveEisenmenger's
  • Eisenmenger'sdefect
  • Fallot'spentalogy
  • Persistence, persistentbulbus cordis in left ventricle
  • Prematureclosure, foramen ovale
  • Anomaly, anomalouscardiacseptal closurespecified NEC
  • Anomaly, anomalousheartseptumspecified NEC
  • Malformationcardiacseptumspecified type NEC

Related codes at this level

Codes that share Q21. If Q21.8 is not quite right, the correct code is usually one of these.

Questions about Q21.8

Is Q21.8 a billable ICD-10-CM code?
Yes. Q21.8 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does Q21.8 sit in the tabular list?
Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0), in the block Congenital malformations of the circulatory system (Q20-Q28).
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.