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Q21.12 — Patent foramen ovale
Q21.12
What this code means
A patent foramen ovale is a small flap-like opening between the heart's upper chambers that failed to close after birth; very common and usually harmless.
Also called: patent foramen ovale, pfo.
When this code is used
Used for patent foramen ovale.
Where it sits in ICD-10-CM
Code Q21.12 belongs to Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders, which covers codes Q00–QA1 in the FY2027 ICD-10-CM tabular list. The official description above is copied verbatim from the CDC/NCHS FY2027 code file.
Related anatomy
Frequently asked questions
What is ICD-10-CM code Q21.12?
Q21.12 is the ICD-10-CM diagnosis code for “Patent foramen ovale”. A patent foramen ovale is a small flap-like opening between the heart's upper chambers that failed to close after birth; very common and usually harmless.
When is code Q21.12 used?
Used for patent foramen ovale. It belongs to Chapter 17 of ICD-10-CM (Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders).
This guide explains ICD-10-CM codes in plain language for patients, students and other readers. It is educational information only — not coding, billing or medical advice. The code recorded for any real encounter is assigned from the full clinical documentation by the treating team and qualified coders, and only they can decide which code fits a specific case.