2026 ICD-10-CM Diagnosis Code K64.5Perianal venous thrombosis

ICD-10-CM Codes›K00–K95›K55-K64›K64

ICD-10-CM K64.5
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K64.5 is a billable ICD-10-CM diagnosis code for perianal venous thrombosis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 393 through 395. Coders also document this condition as external hemorrhoids. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hemorrhoids.

Code Identity

ICD-10-CM Code
K64.5
Billable Status
Yes — Valid for Submission
Code Describes
Perianal venous thrombosis
Short Description
Perianal venous thrombosis
Same as the full description in the CMS dataset.
Parent Code
K64
Hemorrhoids and perianal venous thrombosis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK64Hemorrhoids and perianal venous thrombosis
This CodeK64.5Perianal venous thrombosis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • External hemorrhoids
  • Hematoma of perianal region
  • Thrombosed external hemorrhoids
  • Thrombosed hemorrhoid incised
  • Thrombosed hemorrhoids
  • Thrombosed internal hemorrhoids

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • External hemorrhoids with thrombosis
  • Perianal hematoma
  • Thrombosed hemorrhoids NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Hematoma(traumatic) (skin surface intact)
      • perianal (nontraumatic)
    • Hemorrhoids(bleeding) (without mention of degree)
      • external
        • with
          • thrombosis
    • Hemorrhoids(bleeding) (without mention of degree)
      • thrombosed
    • Thrombosis, thrombotic(bland) (multiple) (progressive) (silent) (vessel)
      • anal
    • Thrombosis, thrombotic(bland) (multiple) (progressive) (silent) (vessel)
      • perianal venous
    • Thrombosis, thrombotic(bland) (multiple) (progressive) (silent) (vessel)
      • vein (acute)
        • perianal
    • Thrombosis, thrombotic(bland) (multiple) (progressive) (silent) (vessel)
      • venous, perianal

Clinical ClassificationClinical

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

CCSR DIG014
Hemorrhoids
Default principal diagnosis: inpatient Yes · outpatient Yes

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Convert K64.5 to ICD-9-CMHistory

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

ICD-9-CM
455.4 Ext thrombos hemorrhoid
Approximate The match is approximate rather than exact.
ICD-9-CM
455.7 Thrombos hemorrhoids 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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K64.5Overview

Is K64.5 (Hemorrhoids and perianal venous thrombosis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report perianal venous thrombosis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K64.5 group to?

When perianal venous thrombosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 393, 394, 395, with relative weights from 0.6490 to 1.5993 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K64.5?

Under the General Equivalence Mappings, perianal venous thrombosis converts to ICD-9-CM 455.4 (ext thrombos hemorrhoid) and 455.7 (thrombos hemorrhoids NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.