Is O21 a billable ICD-10-CM code?

No. O21 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does O21 sit in the tabular list?

Pregnancy, childbirth and the puerperium (O00-O9A), in the block Other maternal disorders predominantly related to pregnancy (O20-O29).

O21

O21 — Excessive vomiting in pregnancy

Non-billable headerICD-10-CM

O21 is a non-billable header ICD-10-CM code for excessive vomiting in pregnancy. It cannot be billed on its own: choose one of the more specific child codes below.

Other codes that can never be billed with O21

These codes carry an Excludes1 note pointing at O21. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading O21 alone.

R11Nausea and vomiting
E87Other disorders of fluid, electrolyte and acid-base balance

Risk adjustment

O21 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead O21

5 child codes. Green means billable.

Questions about O21

Is O21 a billable ICD-10-CM code?: No. O21 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does O21 sit in the tabular list?: Pregnancy, childbirth and the puerperium (O00-O9A), in the block Other maternal disorders predominantly related to pregnancy (O20-O29).