Question 1

What is ICD-10 code O30.821?

Accepted Answer

O30.821 is the ICD-10-CM diagnosis code for other specified multiple gestation with two or more monoamniotic fetuses, first trimester. A pregnancy with multiple fetuses where two or more babies share the same amniotic sac but have separate placentas, occurring in the first three months of pregnancy. O30.821 sits in the ICD-10-CM chapter for pregnancy, childbirth and the puerperium (o00-o9a), within the section covering maternal care related to the fetus and amniotic cavity and possible delivery problems (o30-o48).

O30.821 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 requires documentation of the specific trimester; use 821 only for first trimester cases.

Question 2

Is O30.821 an HCC code?

Accepted Answer

No. O30.821 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 O30.821 billable?

Accepted Answer

Yes. O30.821 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. O30.821 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 O30.821?

Accepted Answer

O30.821 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 O30.821 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 O30.821?

Accepted Answer

This code requires documentation of the specific trimester; use 821 only for first trimester cases Monoamniotic pregnancies carry increased risk of cord entanglement and require specialized prenatal monitoring

O30.821

Is O30.821 an HCC code?

What This Code Means

Coding Tips

Code Hierarchy

Open O30.821 in the Interactive Encoder