2027 ICD-10-CM Diagnosis Code K31.1Adult hypertrophic pyloric stenosis
ICD-10-CM Codes›K00–K95›K20-K31›K31
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
K31.1 is a billable ICD-10-CM diagnosis code for adult hypertrophic pyloric stenosis. 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 complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 20 closely related codes. The code is restricted by the Medicare Code Editor to adult patients (age 15 through 124). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified disorders of stomach and duodenum.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for K31.1.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acquired hypertrophic pyloric stenosis
- Acquired nonhypertrophic constriction of pylorus
- Acquired obstruction of pylorus
- Acquired pyloric constriction
- Acquired pyloric stricture
- Adult hypertrophic pyloric stenosis
- Peptic ulcer with hemorrhage, with perforation AND with obstruction
- Pyloric antral stenosis
- Pyloric obstruction
- Pyloric obstruction due to gallstone
- Pyloric stenosis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to K31.1: its own notes plus those printed at K31, 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.
- functional disorders of stomach
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Acquired hypertrophic pyloric stenosis
- Adult pyloric stenosis
- Pyloric stenosis NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- congenital pyloric stenosis (Q40.0)
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)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name K31.1, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Constriction See Also: Stricture;
pylorus, adult See Also: Stricture, pylorus; K31.1
Stenosis, stenotic (cicatricial) See Also: Stricture;
pylorus (hypertrophic) (acquired) K31.1
adult K31.1
Stricture See Also: Stenosis;
pylorus (hypertrophic) K31.1
adult K31.1
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Stomach Disorders
Your stomach is an organ between your esophagus and small intestine. It is where digestion of protein begins. The stomach has three tasks. It stores swallowed food. It mixes the food with stomach acids. Then it sends the mixture on to the small intestine.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert K31.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About K31.1Overview
What is the ICD-10 code for adult hypertrophic pyloric stenosis?
The ICD-10-CM code for adult hypertrophic pyloric stenosis is K31.1 (sometimes written as K311). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is K31.1 (Other diseases of stomach and duodenum) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adult hypertrophic pyloric stenosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does K31.1 group to?
When adult hypertrophic pyloric stenosis 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 K31.1 a CC or MCC?
CMS lists K31.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 20 closely related codes in its exclusion list.
Who can K31.1 be reported for?
The Medicare Code Editor checks adult hypertrophic pyloric stenosis against patient demographics: this code is intended for adult patients (age 15 through 124). Claims outside these limits are flagged as inconsistent.
