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ICD-10-CM 2027 diagnosis code

O10.01Pre-existing essential hypertension complicating pregnancy

Not billable — use a more specific code

O10.01 is a header code, so it can't be reported by itself. Choose one of the 4 more specific codes beneath it.

Code last changed in FY2022 (effective October 1, 2021). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About O10.01

O10.01 is the ICD-10-CM diagnosis code for pre-existing essential hypertension complicating pregnancy. It belongs to category O10 (pre-existing hypertension complicating pregnancy, childbirth and the puerperium), block O10-O16 (edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium) and chapter 15 (pregnancy, childbirth and the puerperium). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.

Within O10.0 (pre-existing essential hypertension complicating pregnancy, childbirth and the puerperium), O10.01 is specifically for pre-existing essential hypertension complicating pregnancy. Related codes cover childbirth (O10.02) and the puerperium (O10.03).

To report this condition, pick the subcode that matches the documentation: O10.011 (first trimester), O10.012 (second trimester), O10.013 (third trimester) and O10.019 (unspecified trimester).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015, and changed in FY2022 (title revised).

Specific codes under O10.01

Notes that apply from higher levels

Instructions written at a parent level also apply to O10.01.

› From O10 Pre-existing hypertension complicating pregnancy, childbirth and the puerperium
Includes
  • pre-existing hypertension with pre-existing proteinuria complicating pregnancy, childbirth and the puerperium
Excludes2
  • pre-existing hypertension with superimposed pre-eclampsia complicating pregnancy, childbirth and the puerperium (O11.-)

Broader instructions also apply from Chapter 15: Pregnancy, childbirth and the puerperium.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to O10.01.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • FY2022 (effective 10/1/2021): Title revised — was “Pre-existing essential hypertension complicating pregnancy,”

Common questions about O10.01

Is O10.01 billable?

No. O10.01 is a header code. Report one of its more specific subcodes instead.