Question 1

What is ICD-10 code O43.121?

Accepted Answer

O43.121 is the ICD-10-CM diagnosis code for velamentous insertion of umbilical cord, first trimester. The umbilical cord is abnormally attached to the placenta with blood vessels exposed and unprotected by the placental tissue, detected during the first trimester of pregnancy. O43.121 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).

O43.121 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.

Velamentous insertion is a significant finding that increases risk of cord rupture if membranes rupture.

Question 2

Is O43.121 an HCC code?

Accepted Answer

No. O43.121 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 O43.121 billable?

Accepted Answer

Yes. O43.121 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. O43.121 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 O43.121?

Accepted Answer

O43.121 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 O43.121 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 O43.121?

Accepted Answer

Velamentous insertion is a significant finding that increases risk of cord rupture if membranes rupture. Ensure first trimester documentation (weeks 1-13) is present to use this specific code.

HCC Buddy Code Card

O43.121

Is O43.121 an HCC code?

What This Code Means

Coding Tips

Child Codes

Code Hierarchy

Open O43.121 in the Interactive Encoder

O43.121 ICD-10-CM Code: Velamentous insertion of umbilical cord, first trimester

HCC Buddy Code Card

O43.121

Is O43.121 an HCC code?

What This Code Means

Coding Tips

Child Codes

Code Hierarchy

Open O43.121 in the Interactive Encoder