ICD-10-CM 2027 diagnosis code
I99.8Other disorder of circulatory system
I99.8 is a valid, billable ICD-10-CM code for other disorder of circulatory system. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Ischemia, ICD-10 code for Angiectasis, ICD-10 code for Vascular insufficiency, ICD-10 code for Fluctuating blood pressure.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About I99.8
I99.8 is the ICD-10-CM diagnosis code for other disorder of circulatory system. It belongs to category I99 (other and unspecified disorders of circulatory system), block I95-I99 (other and unspecified disorders of the circulatory system) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within I99, choose I99.8 (Other disorder of circulatory system) only when documentation doesn't support a more specific option: unspecified disorder of circulatory system (I99.9).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 302 (Atherosclerosis with MCC, relative weight 1.1984) and DRG 303 (Atherosclerosis without MCC, relative weight 0.6612), in MDC 05 (Diseases and Disorders of the Circulatory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 459.89 (other specified disorders of circulatory system).
Notes that apply from higher levels
Instructions written at a parent level also apply to I99.8.
Broader instructions also apply from Chapter 9: Diseases of the circulatory system.
Alphabetic index entries
19 entriesTerms in the official ICD-10-CM index that lead to I99.8.
- Angiectasis, angiectopia
- Atrophy, atrophic (of) › vascular
- Blood › pressure › fluctuating
- Circulation › collateral, any site
- Complication (s) (from) (of) › circulatory system
- Congestion, congestive › circulatory NEC
- Dilatation › blood vessel
- Disease, diseased › circulatory (system) NEC
- Disease, diseased › vascular › occlusive
- Dissection › vascular
- Fluctuating blood pressure
- Insufficiency, insufficient › arteriovenous
- Insufficiency, insufficient › circulatory NEC
- Insufficiency, insufficient › vascular
- Ischemia, ischemic
- Obstruction, obstructed, obstructive › circulatory
- Obstruction, obstructed, obstructive › vessel NEC
- Occlusion, occluded › vascular NEC
- Occlusion, occluded › vessel (blood)
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.
MDC 05 · Diseases and Disorders of the Circulatory System
ICD-9-CM equivalent
Converter →- 459.89Other specified disorders of circulatory systemapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about I99.8
Is I99.8 billable?
- Yes. I99.8 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I99.8 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I99.8 as a principal diagnosis.
Is I99.8 a CC or MCC?
- No. I99.8 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does I99.8 group to?
- I99.8 is used in the MS-DRG v44.0 logic for MS-DRG 302 (Atherosclerosis with MCC) and MS-DRG 303 (Atherosclerosis without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for I99.8?
- The CMS General Equivalence Mappings map I99.8 to ICD-9-CM 459.89.