2027 ICD-10-CM Diagnosis Code K26.1Acute duodenal ulcer with perforation
ICD-10-CM Codes›K00–K95›K20-K31›K26
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 78
- Not Chronic
K26.1 is a billable ICD-10-CM diagnosis code for acute duodenal ulcer with perforation. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 380 through 382. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 76 closely related codes. Coders also document this condition as acute duodenal ulcer with obstruction. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastroduodenal ulcer and Gastrointestinal and biliary perforation.
For Medicare Advantage risk adjustment, K26.1 maps to CMS-HCC Category 78 (Intestinal Obstruction/Perforation) under the V28 model, adding a risk factor of about 0.326 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
K26.1 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute duodenal ulcer with obstruction
- Acute duodenal ulcer with perforation
- Acute duodenal ulcer with perforation AND obstruction
- Acute duodenal ulcer with perforation but without obstruction
- Acute peptic ulcer with perforation AND obstruction
- Duodenal ulcer with perforation AND obstruction
- Duodenal ulcer with perforation but without obstruction
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to K26.1: its own notes plus those printed at K26, block K20-K31, and Chapter 11. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- erosion (acute) of duodenum
- duodenum ulcer (peptic)
- postpyloric ulcer (peptic)
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- hiatus hernia (K44.-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name K26.1, its category, or a range that includes it.
Excludes1 3
These codes carry an Excludes1 note naming K26.1: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Duodenal Ulcer
a peptic ulcer located in the duodenum.
Patient EducationClinical
Peptic Ulcer
A peptic ulcer is a sore in the lining of your stomach or your duodenum, the first part of your small intestine. A burning stomach pain is the most common symptom. The pain:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert K26.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About K26.1Overview
What is the ICD-10 code for acute duodenal ulcer with perforation?
The ICD-10-CM code for acute duodenal ulcer with perforation is K26.1 (sometimes written as K261). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is K26.1 (Duodenal ulcer) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report acute duodenal ulcer with perforation on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does K26.1 group to?
When acute duodenal ulcer with perforation is the principal diagnosis on an inpatient stay, it groups to MS-DRG 381, 380, 382, with relative weights from 0.7283 to 1.9243 depending on complications. Higher weights mean higher Medicare reimbursement.
Is K26.1 a CC or MCC?
CMS lists K26.1 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 76 closely related codes in its exclusion list.
Can K26.1 be reported with a code from K27?
Not as a rule. The Excludes1 note at K26, which applies to K26.1, lists "peptic ulcer NOS (K27.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is K26.1?
K26.1 (acute duodenal ulcer with perforation) maps to CMS-HCC Category 78 (Intestinal Obstruction/Perforation), commonly written as HCC 78, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 33 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does K26.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, K26.1 adds a risk adjustment factor of about 0.326 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.326 to 0.688 depending on the payment segment). A more severe related category (HCC 77) supersedes it when both are reported. See the full factor table on the HCC 78 category page.
