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ICD-10-CM 2027 diagnosis code

O00.121Right interstitial ectopic pregnancy without intrauterine pregnancy

✓ Billable / specificNew for 2027CC — complication/comorbidityMaternity · age 9–64

O00.121 is a valid, billable ICD-10-CM code for right interstitial ectopic pregnancy without intrauterine pregnancy. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Right interstit ectopic pregnancy without uterin pregnancy

Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS, effective October 1, 2026. Updated September 29, 2026. About our data

About O00.121

O00.121 is the ICD-10-CM diagnosis code for right interstitial ectopic pregnancy without intrauterine pregnancy. It belongs to category O00 (ectopic pregnancy), block O00-O08 (pregnancy with abortive outcome) and chapter 15 (pregnancy, childbirth and the puerperium). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within O00.12, choose O00.121 (Right interstitial ectopic pregnancy without intrauterine pregnancy) only when documentation doesn't support a more specific option: left interstitial ectopic pregnancy without intrauterine pregnancy (O00.122) and unspecified interstitial ectopic pregnancy without intrauterine pregnancy (O00.129).

Use an additional code from category O08 to identify any associated complication.

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 817 (Other Antepartum Diagnoses with O.R. Procedures with MCC, relative weight 2.0534), DRG 818 (Other Antepartum Diagnoses with O.R. Procedures with CC, relative weight 1.2942), DRG 819 (Other Antepartum Diagnoses with O.R. Procedures without CC/MCC, relative weight 0.7739), DRG 831 (Other Antepartum Diagnoses without O.R. Procedures with MCC, relative weight 1.1558), DRG 832 (Other Antepartum Diagnoses without O.R. Procedures with CC, relative weight 0.7585) and DRG 833 (Other Antepartum Diagnoses without O.R. Procedures without CC/MCC, relative weight 0.5002), in MDC 14 (Pregnancy, Childbirth and the Puerperium), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

The Medicare Code Editor treats this as a maternity diagnosis, expected only for patients age 9 through 64.

It was added in FY2027, effective October 1, 2026.

Notes that apply from higher levels

Instructions written at a parent level also apply to O00.121.

› From O00 Ectopic pregnancy
Includes
  • ruptured ectopic pregnancy
Use additional code
  • code from category O08 to identify any associated complication

Broader instructions also apply from O00-O08 Pregnancy with abortive outcome and Chapter 15: Pregnancy, childbirth and the puerperium.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

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
  • FY2027 (effective 10/1/2026): Added

Common questions about O00.121

Is O00.121 billable?

Yes. O00.121 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can O00.121 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict O00.121 as a principal diagnosis.

Is O00.121 a CC or MCC?

O00.121 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does O00.121 group to?

O00.121 is used in the MS-DRG v44.0 logic for MS-DRG 817 (Other Antepartum Diagnoses with O.R. Procedures with MCC), MS-DRG 818 (Other Antepartum Diagnoses with O.R. Procedures with CC), MS-DRG 819 (Other Antepartum Diagnoses with O.R. Procedures without CC/MCC), MS-DRG 831 (Other Antepartum Diagnoses without O.R. Procedures with MCC), MS-DRG 832 (Other Antepartum Diagnoses without O.R. Procedures with CC) and MS-DRG 833 (Other Antepartum Diagnoses without O.R. Procedures without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

Did O00.121 change for 2027?

Yes. For FY2027 (effective October 1, 2026) it was added to the code set.