ICD-10 Code I27.849 – Fontan related circulation, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I27.849 – Fontan related circulation, unspecified
What it is
This code identifies a Fontan circulation in a patient with complex single-ventricle congenital heart disease, when the record does not specify a more detailed complication or subtype. Use it when the documentation simply states Fontan related circulation, unspecified.
Clinical signs
Clinical features vary; refer to documentation. Patients may have findings related to the Fontan physiology, such as chronic circulatory limitations or follow-up for the Fontan pathway, but you should code only what is documented.
When to use this code
Use I27.849 when the provider documents Fontan related circulation and gives no further detail, such as a specific failure, obstruction, or other named complication. It is appropriate for encounters focused on ongoing assessment, surveillance, or management of the Fontan circulation. If a more specific diagnosis is documented, choose that code instead.
Do not use for
Do not use this code for general congenital heart defects without a Fontan circulation. Also avoid it when the chart documents a specific Fontan complication or another clearer diagnosis; check documentation.
Coding tip
Code the most specific Fontan-related diagnosis available, and use I27.849 only when the record stays nonspecific.