2026 ICD-10-CM Diagnosis Code K59.39Other megacolon

ICD-10-CM Codes›K00–K95›K55-K64›K59

ICD-10-CM K59.39
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K59.39 is a billable ICD-10-CM diagnosis code for other megacolon. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified gastrointestinal disorders.

Code Identity

ICD-10-CM Code
K59.39
Billable Status
Yes — Valid for Submission
Code Describes
Other megacolon
Short Description
Other megacolon
Same as the full description in the CMS dataset.
Parent Code
K59.3
Megacolon, not elsewhere classified

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK59Other functional intestinal disorders
This CodeK59.39Other megacolon

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired megacolon
  • Acquired megacolon in adult
  • Acquired megacolon in child
  • Idiopathic megacolon
  • Idiopathic megacolon in adult
  • Idiopathic megacolon in child
  • Piulachs-Hederich syndrome
  • Secondary acquired megacolon
  • Toxic megacolon due to amebic infection
  • Toxic megacolon due to infectious colitis
  • Toxic state
  • Toxic state due to colonic dilatation

Tabular List NotesGuidance

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

Inclusion Terms

  • Megacolon 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.

    • Dilatation
      • colon
    • Dilatation
      • rectum
    • Excess, excessive, excessively
      • large
        • colon
    • Macrosigmoid
    • Megacolon(acquired) (functional) (not Hirschsprung's disease) (in)
    • Megasigmoid
    • Syndrome
      • faulty bowel habit

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

  • Hirschsprung Disease

    congenital megacolon resulting from the absence of ganglion cells (aganglionosis) in a distal segment of the large intestine. the aganglionic segment is permanently contracted thus causing dilatation proximal to it. in most cases, the aganglionic segment is within the rectum and sigmoid colon.

  • Megacolon

    dilatation of the colon, often to alarming dimensions. there are various types of megacolon including congenital megacolon in hirschsprung disease, idiopathic megacolon in constipation, and toxic megacolon.

  • Megacolon, Toxic

    an acute form of megacolon, severe pathological dilatation of the colon. it is associated with clinical conditions such as ulcerative colitis; crohn disease; amebic dysentery; or clostridium enterocolitis.

  • Hirschsprung Disease|Aganglionic Megacolon|Hirschsprung's Disease|Hirschsprung's Disease

    a congenital disorder characterized by the absence of myenteric ganglion cells in the distal colon. it results in a functional stenosis of the distal colon and a massive distention of the proximal colon.

  • Megacolon

    an abnormal dilation of the colon not due to obstruction.

  • SOX10 wt Allele|DOM|Dominant Megacolon, Mouse, Human Homolog of Gene|PCWH|RP5-1039K5.9|SRY (Sex Determining Region Y)-Box 10 wt Allele|SRY-Related HMG-Box Gene 10|WS2E|WS4|WS4C

    human sox10 wild-type allele is located in the vicinity of 22q13.1 and is approximately 17 kb in length. this allele, which encodes transcription factor sox-10 protein, plays a role in transcriptional activation. mutation of the gene is associated with waardenburg syndrome types 2e and 4c and with peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, waardenburg syndrome, and hirschsprung disease.

Convert K59.39 to ICD-9-CMHistory

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

ICD-9-CM
564.7 Megacolon NEC
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement K59.39 replaces the following previously assigned code(s):

  • K59.3 - Megacolon, not elsewhere classified
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 K59.39Overview

Is K59.39 (Megacolon, not elsewhere classified) a billable code?

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

What MS-DRG does K59.39 group to?

When other megacolon 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 K59.39?

Under the General Equivalence Mappings, other megacolon converts to ICD-9-CM 564.7 (megacolon NEC). 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.