2027 ICD-10-CM Diagnosis Code K31.BHypertrophic pyloric stenosis, in childhood

ICD-10-CM Codes›K00–K95›K20-K31›K31

ICD-10-CM K31.B
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

K31.B is a billable ICD-10-CM diagnosis code for hypertrophic pyloric stenosis, in childhood. 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 pediatric patients (age 0 through 17).

Code Identity

ICD-10-CM Code
K31.B
Billable Status
Yes — Valid for Submission
Code Describes
Hypertrophic pyloric stenosis, in childhood
Short Description
Hypertrophic pyloric stenosis, in childhood
Same as the full description in the CMS dataset.
Parent Code
K31
Other diseases of stomach and duodenum

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK20-K31Diseases of esophagus, stomach and duodenum
CategoryK31Other diseases of stomach and duodenum
This CodeK31.BHypertrophic pyloric stenosis, in childhood

Code EditsBilling

Medicare Code Editor checks that affect claim validity for K31.B.

Pediatric diagnoses
The Medicare Code Editor detects inconsistencies in pediatric cases by checking a patient's age and any diagnosis on the patient's record. The pediatric code edits apply to patients age range is 0–17 years inclusive (e.g., Reye's syndrome, routine child health exam).

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to K31.B: 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.

From K31 Other diseases of stomach and duodenum applies to 26 codes
  • 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.

  • Infantile hypertrophic pyloric stenosis
  • Pediatric hypertrophic pyloric stenosis
  • Pediatric pyloric stenosis

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.

From K31 Other diseases of stomach and duodenum applies to 26 codes
From Block K20-K31 Diseases of esophagus, stomach and duodenum applies to 106 codes
From Chapter 11 (K00-K95) Diseases of the digestive system applies to 863 codes
  • 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.B, its category, or a range that includes it.

Excludes2 1

These codes carry an Excludes2 note naming K31.B: its condition is not part of those codes, and both may be reported when the patient has both.

  • K59 Other functional intestinal disorders
    functional disorders of stomach (K31.-) names K31.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical InformationClinical

  • Pyloric Stenosis, Hypertrophic

    narrowing of the pyloric canal due to hypertrophy of the surrounding circular muscle. it is usually seen in infants or young children.

Code History & ChangesHistory

New Code K31.B was added to the ICD-10-CM code set for FY 2027, effective October 1, 2026.

Replacement K31.B replaces the following previously assigned code(s):

  • Q40.0 - Congenital hypertrophic pyloric stenosis
FY 2027AddedAdded to the ICD-10-CM code setEffective October 1, 2026.
FY 2027CurrentRevised in the current code setEffective October 1, 2026 through September 30, 2027.

Questions About K31.BOverview

What is the ICD-10 code for hypertrophic pyloric stenosis, in childhood?

The ICD-10-CM code for hypertrophic pyloric stenosis, in childhood is K31.B (sometimes written as K31B). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is K31.B (Other diseases of stomach and duodenum) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hypertrophic pyloric stenosis, in childhood on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does K31.B group to?

When hypertrophic pyloric stenosis, in childhood 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.B a CC or MCC?

CMS lists K31.B 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.B be reported for?

The Medicare Code Editor checks hypertrophic pyloric stenosis, in childhood against patient demographics: this code is intended for pediatric patients (age 0 through 17). Claims outside these limits are flagged as inconsistent.