Question 1

What is ICD-10 code Y65.51?

Accepted Answer

Y65.51 is the ICD-10-CM diagnosis code for performance of wrong procedure (operation) on correct patient. A surgeon performed the correct surgical procedure, but it was the wrong procedure for that particular patient's condition or needs. Y65.51 sits in the ICD-10-CM chapter for external causes of morbidity (v00-y99), within the section covering misadventures to patients during surgical and medical care (y62-y69).

Y65.51 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

This differs from wrong site surgery; document what procedure was performed versus what should have been performed.

Question 2

Is Y65.51 an HCC code?

Accepted Answer

No. Y65.51 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is Y65.51 billable?

Accepted Answer

Yes. Y65.51 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. Y65.51 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

What is the V28 vs V24 difference for Y65.51?

Accepted Answer

Y65.51 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards Y65.51 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting Y65.51?

Accepted Answer

This differs from wrong site surgery; document what procedure was performed versus what should have been performed Coordinate with the operative report to clearly establish the discrepancy between planned and performed procedures

Y65.51

Is Y65.51 an HCC code?

What This Code Means

Coding Tips

Excludes 1 — Do NOT code together

Code Hierarchy

Open Y65.51 in the Interactive Encoder