2027 ICD-10-CM Diagnosis Code G45.9Transient cerebral ischemic attack, unspecified

ICD-10-CM Codes›G00–G99›G40-G47›G45

ICD-10-CM G45.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G45.9 is a billable ICD-10-CM diagnosis code for transient cerebral ischemic attack, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 61 through 63, 69. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 115 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Transient cerebral ischemia.

Code Identity

ICD-10-CM Code
G45.9
Billable Status
Yes — Valid for Submission
Code Describes
Transient cerebral ischemic attack, unspecified
Short Description
Transient cerebral ischemic attack, unspecified
Same as the full description in the CMS dataset.
Parent Code
G45
Transient cerebral ischemic attacks and related syndromes

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG45Transient cerebral ischemic attacks and related syndromes
This CodeG45.9Transient cerebral ischemic attack, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arteriospasm
  • Intermittent cerebral ischemia
  • Recurrent transient cerebral ischemic attack
  • Spasm of cerebral arteries
  • Stroke/transient ischemic attack monitoring first letter
  • Stroke/transient ischemic attack monitoring invitation
  • Stroke/transient ischemic attack monitoring second letter
  • Stroke/transient ischemic attack monitoring status
  • Stroke/transient ischemic attack monitoring third letter
  • Stroke/transient ischemic attack monitoring verbal invitation
  • Transient cerebral ischemia
  • Transient cerebral ischemia due to atrial fibrillation
  • Transient ischemic attack co-occurrent with subarachnoid hemorrhage
  • Transient ischemic attack due to embolism
  • Vasospasm

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G45.9: its own notes plus those printed at G45 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Spasm of cerebral artery
  • TIA
  • Transient cerebral ischemia NOS

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From G45 Transient cerebral ischemic attacks and related syndromes applies to 7 codes
  • neonatal cerebral ischemia (P91.0)
  • transient retinal artery occlusion (H34.0-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G45.9, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming G45.9: they are not reported together with it, unless the two conditions are unrelated.

  • R29.5 Transient paralysis
    transient ischemic attack (G45.9)
  • I65 Occlusion and stenosis of precerebral arteries, not resulting in cerebral infarction
    insufficiency, NOS, of precerebral artery (G45.-) names G45.-, which includes this code

Excludes2 5

These codes carry an Excludes2 note naming G45.9: its condition is not part of those codes, and both may be reported when the patient has both.

  • I69.322 Dysarthria following cerebral infarction
    transient ischemic attack (TIA) (G45.9)
  • I69.351 Hemiplegia and hemiparesis following cerebral infarction affecting right dominant side
    transient ischemic attack (TIA) (G45.9)
  • I73 Other peripheral vascular diseases
    spasm of cerebral artery (G45.9)
  • Chapter 9 (I00-I99) Diseases of the circulatory system
    transient cerebral ischemic attacks and related syndromes (G45.-) names G45.-, which includes this code
  • I63.9 Cerebral infarction, unspecified
    transient cerebral ischemic attacks and related syndromes (G45.-) names G45.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS012
Transient cerebral ischemia
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Transient Ischemic Attack

    a brief attack (from a few minutes to an hour) of cerebral dysfunction of vascular origin, with no persistent neurological deficit.

Patient EducationClinical

Transient Ischemic Attack

A transient ischemic attack (TIA) is a stroke that lasts only a few minutes. It happens when the blood supply to part of the brain is briefly blocked. Symptoms of a TIA are like other stroke symptoms, but do not last as long. They happen suddenly, and include:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G45.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
435.9 Trans cereb ischemia NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About G45.9Overview

What is the ICD-10 code for transient cerebral ischemic attack, unspecified?

The ICD-10-CM code for transient cerebral ischemic attack, unspecified is G45.9 (sometimes written as G459). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G45.9 (Transient cerebral ischemic attacks and related syndromes) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report transient cerebral ischemic attack, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does G45.9 group to?

When transient cerebral ischemic attack, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 69, 61, 62, 63, with relative weights from 0.7962 to 2.7211 depending on complications. Higher weights mean higher Medicare reimbursement.

Is G45.9 a CC or MCC?

CMS lists G45.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 115 closely related codes in its exclusion list.

Can G45.9 be reported with P91.0?

Not as a rule. The Excludes1 note at G45, which applies to G45.9, lists "neonatal cerebral ischemia (P91.0)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).