2026 ICD-10-CM Diagnosis Code M65.321Trigger finger, right index finger

ICD-10-CM Codes›M00–M99›M65-M67›M65

ICD-10-CM M65.321
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M65.321 is a billable ICD-10-CM diagnosis code for trigger finger, right index finger. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 557 through 558. Coders also document this condition as acquired trigger finger of left index finger. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tendon and synovial disorders.

Code Identity

ICD-10-CM Code
M65.321
Billable Status
Yes — Valid for Submission
Code Describes
Trigger finger, right index finger
Short Description
Trigger finger, right index finger
Same as the full description in the CMS dataset.
Parent Code
M65.32
Trigger finger, index finger

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM65-M67Disorders of synovium and tendon
CategoryM65Synovitis and tenosynovitis
This CodeM65.321Trigger finger, right index finger

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired trigger finger of left index finger
  • Acquired trigger finger of right index finger
  • Bilateral acquired deformity of finger of hands
  • Bilateral acquired deformity of hands
  • Bilateral acquired trigger finger of index fingers
  • Bilateral trigger fingers
  • Trigger finger of left hand
  • Trigger finger of right hand

Clinical ClassificationClinical

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

CCSR MUS009
Tendon and synovial disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Finger Injuries and Disorders

You use your fingers and thumbs to do everything from grasping objects to playing musical instruments to typing. When there is something wrong with them, it can make life difficult. Common problems include:

Read the full article at MedlinePlus

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

Convert M65.321 to ICD-9-CMHistory

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

ICD-9-CM
727.03 Trigger finger
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 M65.321Overview

Is M65.321 (Trigger finger, index finger) a billable code?

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

What MS-DRG does M65.321 group to?

When trigger finger, right index finger is the principal diagnosis on an inpatient stay, it groups to MS-DRG 557, 558, with relative weights from 0.8932 to 1.4869 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M65.321?

Under the General Equivalence Mappings, trigger finger, right index finger converts to ICD-9-CM 727.03 (trigger finger). 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.