2026 ICD-10-CM Diagnosis Code K91.1Postgastric surgery syndromes

ICD-10-CM Codes›K00–K95›K90-K95›K91

ICD-10-CM K91.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K91.1 is a billable ICD-10-CM diagnosis code for postgastric surgery syndromes. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Postprocedural or postoperative digestive system complication.

Code Identity

ICD-10-CM Code
K91.1
Billable Status
Yes — Valid for Submission
Code Describes
Postgastric surgery syndromes
Short Description
Postgastric surgery syndromes
Same as the full description in the CMS dataset.
Parent Code
K91
Intraoperative and postprocedural complications and disorders of digestive system, not elsewhere classified

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK90-K95Other diseases of the digestive system
CategoryK91Intraoperative and postprocedural complications and disorders of digestive system, not elsewhere classified
This CodeK91.1Postgastric surgery syndromes

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Alimentary hypoglycemia
  • Diarrhea after gastrointestinal tract surgery
  • Early dumping syndrome
  • Familial duodenal ulcer associated with rapid gastric emptying
  • Gastric necrosis
  • Late dumping syndrome
  • Metabolic complication of procedures
  • Non-infective diarrhea
  • Post gastrointestinal tract surgery hypoglycemia
  • Postgastric surgery syndrome
  • Post-vagotomy diarrhea
  • Post-vagotomy lesser curve necrosis
  • Post-vagotomy syndrome
  • Reactive hypoglycemia
  • Small stomach syndrome
  • Vitamin B12 deficiency anemia following gastrectomy

Tabular List NotesGuidance

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

Inclusion Terms

  • Dumping syndrome
  • Postgastrectomy syndrome
  • Postvagotomy syndrome

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.

    • Achlorhydria, achlorhydric(neurogenic)
      • secondary to vagotomy
    • Complication(s) (from) (of)
      • gastrointestinal
        • postoperative
          • dumping syndrome
    • Complication(s) (from) (of)
      • surgical procedure (on)
        • dumping syndrome (postgastrectomy)
    • Complication(s) (from) (of)
      • surgical procedure (on)
        • postgastrectomy dumping syndrome
    • Complication(s) (from) (of)
      • surgical procedure (on)
        • postvagotomy syndrome
    • Diarrhea, diarrheal(disease) (infantile) (inflammatory)
      • postgastrectomy
    • Diarrhea, diarrheal(disease) (infantile) (inflammatory)
      • postvagotomy
    • Dumping syndrome(postgastrectomy)
    • Postgastrectomy dumping syndrome
    • Syndrome
      • dumping (postgastrectomy)
    • Syndrome
      • postgastrectomy (dumping)
    • Syndrome
      • postgastric surgery
    • Syndrome
      • postvagotomy

Clinical ClassificationClinical

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

CCSR DIG024
Postprocedural or postoperative digestive system complication
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

After Surgery

After any operation, you'll have some side effects. There is usually some pain with surgery. There may also be swelling and soreness around the area that the surgeon cut. Your surgeon can tell you which side effects to expect.

Read the full article at MedlinePlus

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

Convert K91.1 to ICD-9-CMHistory

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

ICD-9-CM
564.2 Postgastric surgery synd
Exact Match The mapping is direct, with no qualifiers.

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 K91.1Overview

Is K91.1 a billable code?

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

What MS-DRG does K91.1 group to?

When postgastric surgery syndromes 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 K91.1?

Under the General Equivalence Mappings, postgastric surgery syndromes converts to ICD-9-CM 564.2 (postgastric surgery synd). The mapping is a direct match.

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.