2026 ICD-10-CM Diagnosis Code K59.04Chronic idiopathic constipation

ICD-10-CM Codes›K00–K95›K55-K64›K59

ICD-10-CM K59.04
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K59.04 is a billable ICD-10-CM diagnosis code for chronic idiopathic constipation. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 391 through 392. Coders also document this condition as chronic constipation. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified gastrointestinal disorders.

Code Identity

ICD-10-CM Code
K59.04
Billable Status
Yes — Valid for Submission
Code Describes
Chronic idiopathic constipation
Short Description
Chronic idiopathic constipation
Same as the full description in the CMS dataset.
Parent Code
K59.0
Constipation

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK59Other functional intestinal disorders
This CodeK59.04Chronic idiopathic constipation

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chronic constipation
  • Chronic idiopathic constipation
  • Functional constipation
  • Functional constipation of infant
  • NRXN1-related severe neurodevelopmental disorder, motor stereotypies, chronic constipation, sleep-wake cycle disturbance

Tabular List NotesGuidance

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

Inclusion Terms

  • Functional constipation

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.

    • Constipation(atonic) (neurogenic) (simple) (spastic)
      • chronic
        • idiopathic
    • Constipation(atonic) (neurogenic) (simple) (spastic)
      • functional

Clinical ClassificationClinical

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

CCSR DIG025
Other specified and unspecified gastrointestinal disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Constipation

    infrequent or difficult evacuation of feces. these symptoms are associated with a variety of causes, including low dietary fiber intake, emotional or nervous disturbances, systemic and structural disorders, drug-induced aggravation, and infections.

  • Opioid-Induced Constipation

    constipation associated with the use of opioids.

Patient EducationClinical

Constipation

Constipation means having fewer than three bowel movements a week. The stool (poop) can be hard and dry. Sometimes it is painful to pass. At one time or another, almost everyone gets constipated. In most cases, it lasts a short time and is not serious.

Read the full article at MedlinePlus

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

Convert K59.04 to ICD-9-CMHistory

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

ICD-9-CM
564.09 Constipation NEC
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement K59.04 replaces the following previously assigned code(s):

  • K59.09 - Other constipation
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K59.04Overview

Is K59.04 (Constipation) a billable code?

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

What MS-DRG does K59.04 group to?

When chronic idiopathic constipation is the principal diagnosis on an inpatient stay, it groups to MS-DRG 391, 392, with relative weights from 0.7796 to 1.2683 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K59.04?

Under the General Equivalence Mappings, chronic idiopathic constipation converts to ICD-9-CM 564.09 (constipation NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.