Question 1

What is ICD-10 code O86.4?

Accepted Answer

O86.4 is the ICD-10-CM diagnosis code for pyrexia of unknown origin following delivery. A fever that develops after childbirth where the cause cannot be identified or determined despite investigation. O86.4 sits in the ICD-10-CM chapter for pregnancy, childbirth and the puerperium (o00-o9a), within the section covering complications predominantly related to the puerperium (o85-o92).

O86.4 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 code should only be used when fever is present but the underlying cause remains unknown after evaluation.

Question 2

Is O86.4 an HCC code?

Accepted Answer

No. O86.4 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 O86.4 billable?

Accepted Answer

Yes. O86.4 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. O86.4 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 O86.4?

Accepted Answer

O86.4 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 O86.4 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 O86.4?

Accepted Answer

This code should only be used when fever is present but the underlying cause remains unknown after evaluation Document the fever duration and any diagnostic workup performed to support this diagnosis

O86.4

Is O86.4 an HCC code?

What This Code Means

Coding Tips

Excludes 2 — Not included here, may code separately

Code Hierarchy

Open O86.4 in the Interactive Encoder