2027 ICD-10-CM Diagnosis Code K40.91Unilateral inguinal hernia, without obstruction or gangrene, recurrent

ICD-10-CM Codes›K00–K95›K40-K46›K40

ICD-10-CM K40.91
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

K40.91 is a billable ICD-10-CM diagnosis code for unilateral inguinal hernia, without obstruction or gangrene, recurrent. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 393 through 395. Coders also document this condition as recurrent inguinal hernia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Abdominal hernia.

Code Identity

ICD-10-CM Code
K40.91
Billable Status
Yes — Valid for Submission
Code Describes
Unilateral inguinal hernia, without obstruction or gangrene, recurrent
Short Description
Unilateral inguinal hernia, w/o obst or gangrene, recurrent
Parent Code
K40.9
Unilateral inguinal hernia, without obstruction or gangrene

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK40-K46Hernia
CategoryK40Inguinal hernia
This CodeK40.91Unilateral inguinal hernia, without obstruction or gangrene, recurrent

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Recurrent inguinal hernia
  • Recurrent left inguinal hernia
  • Recurrent right inguinal hernia

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to K40.91: its own notes plus those printed at K40, block K40-K46, 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 K40 Inguinal hernia applies to 12 codes
  • bubonocele
  • direct inguinal hernia
  • double inguinal hernia
  • indirect inguinal hernia
  • inguinal hernia NOS
  • oblique inguinal hernia
  • scrotal hernia
From Block K40-K46 Hernia applies to 45 codes
  • acquired hernia
  • congenital [except diaphragmatic or hiatus] hernia
  • recurrent hernia

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 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)

Notes

General instructions on how these codes are used.

From Block K40-K46 Hernia applies to 45 codes
  • Hernia with both gangrene and obstruction is classified to hernia with gangrene.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name K40.91, its category, or a range that includes it.

Excludes2 1

These codes carry an Excludes2 note naming K40.91: its condition is not part of those codes, and both may be reported when the patient has both.

  • K56.7 Ileus, unspecified
    intestinal obstruction with hernia (K40-K46) names K40-K46, which includes this code

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.

CCSR DIG010
Abdominal hernia
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Hernia, Inguinal

    an abdominal hernia with an external bulge in the groin region. it can be classified by the location of herniation. indirect inguinal hernias occur through the internal inguinal ring. direct inguinal hernias occur through defects in the abdominal wall (transversalis fascia) in hesselbach's triangle. the former type is commonly seen in children and young adults; the latter in adults.

Patient EducationClinical

Hernia

A hernia happens when part of an internal organ or tissue bulges through a weak area of muscle. Most hernias are in the abdomen.

Read the full article at MedlinePlus

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

Convert K40.91 to ICD-9-CMHistory

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

ICD-9-CM
550.91 Recur unilat inguin hern
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About K40.91Overview

What is the ICD-10 code for unilateral inguinal hernia, without obstruction or gangrene, recurrent?

The ICD-10-CM code for unilateral inguinal hernia, without obstruction or gangrene, recurrent is K40.91 (sometimes written as K4091). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is K40.91 (Unilateral inguinal hernia, without obstruction or gangrene) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unilateral inguinal hernia, without obstruction or gangrene, recurrent on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does K40.91 group to?

When unilateral inguinal hernia, without obstruction or gangrene, recurrent is the principal diagnosis on an inpatient stay, it groups to MS-DRG 394, 395, 393, with relative weights from 0.6379 to 1.5877 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K40.91?

Under the General Equivalence Mappings, unilateral inguinal hernia, without obstruction or gangrene, recurrent converts to ICD-9-CM 550.91 (recur unilat inguin hern). The mapping is a direct match.