Unspecified appendicitis (K37) ICD-10-CM
The K37 code range covers unspecified appendicitis with 1 ICD-10-CM diagnosis codes. 1 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Codes in the K37 Range 1 codes · 1 billable
- K37 Unspecified appendicitis
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the K37 range.
Appendicitis
Acute inflammation of the APPENDIX. Acute appendicitis is classified as simple, gangrenous, or perforated.
Appendix
A worm-like blind tube extension from the CECUM.
Typhlitis
Necrotizing inflammation of the CECUM (typhlon in Greek), sometimes spreading to the APPENDIX and/or the ILEUM. Symptoms include ABDOMINAL PAIN and DIARRHEA. Its pathogenesis is multifactorial. Typhlitis is often associated with NEUTROPENIA and chemotherapy in immunocompromised individuals (IMMUNOCOMPROMISED HOST).
About the K37 Code Range
The ICD-10 code K37 is used to classify cases of unspecified appendicitis, where the exact type or location of the inflammation in the appendix is not clearly identified. This code applies when documentation does not specify more detailed forms of appendicitis.
When coding for appendicitis conditions, the term "unspecified appendicitis" helps capture diagnoses that do not specify whether the inflammation is, for example, focal appendicitis, retrocecal appendicitis, or periappendicitis. Synonyms like focal appendicitis, retrocecal appendicitis, typhlitis, and even neutropenic typhlitis broadly relate to inflammatory conditions affecting the appendix or nearby intestinal areas. Using code K37 ensures accurate reporting when the exact subtype—such as Crohn disease involving the appendix or other specific forms—is not detailed. This ICD-10 code for unspecified appendicitis is essential for capturing the diagnosis in medical records when precise terminology is lacking, supporting proper treatment and healthcare data management.
Questions About This Page
How many billable codes are in the K37 range?
Of the 1 codes in this range, 1 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the K37 range classify?
The range classifies unspecified appendicitis. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
