Appendicitis ICD-10-CM Codes

Learn about the common ICD-10-CM codes for appendicitis that you can use through this guide.

By Matt Olivares on Jul 16, 2025.

What ICD-10 codes are used for appendicitis?

Appendicitis is a common condition characterized by inflammation of the appendix, usually due to obstruction. Accurate ICD-10 codes are essential for effective diagnosis and proper medical coding.

Here are some commonly used codes for appendicits (do note that these are just some examples because there are a lot of codes):

K35.80 - Unspecified acute appendicitis
K35.891 - Other acute appendicitis without perforation, with gangrene
K35.211 - Acute appendicitis with generalized peritonitis, with perforation and abscess
K35.30 - Acute appendicitis with localized peritonitis, without perforation or gangrene
K35.219 - Acute appendicitis with generalized peritonitis, with abscess, unspecified as to perforation
K35.31 - Acute appendicitis with localized peritonitis and gangrene, without perforation
K35.200 - Acute appendicitis with generalized peritonitis, without perforation or abscess
K35.33 - Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
K37 - Unspecified appendicitis
K36 - Other appendicitis

Almost all of these codes are for acute appendicitis, which is the sudden inflammation of the appendix.

You just need to determine what kind of peritonitis it has (the redness and swelling of the belly or abdominal lining), if it has perforation (if there is a hole), if there's gangrene (death of body tissue), and if there are abscesses (pus buildup).

K37 is only meant to be used if the specific kind of appendicitis isn't known at the moment.

The last code (K36) indicated is for any other type of appendicitis that isn't acute.

Which appendicitis ICD codes are billable?

All of the aforementioned codes are valid and billable.

Clinical information

Appendicitis is an inflammation of the appendix, a small pouch-like organ located in the lower right side of the abdomen.
It is most commonly caused by obstruction of the appendix, leading to bacterial overgrowth and infection.
The typical clinical presentation includes sudden-onset abdominal pain, usually starting around the belly button and moving to the lower right side of the abdomen.
Other common symptoms include loss of appetite, nausea, vomiting, low-grade fever, and tenderness in the right lower quadrant of the abdomen.
Physical examination findings often include rebound tenderness, guarding, and localized tenderness upon palpation of the abdomen.
Diagnostic imaging studies such as ultrasound or computed tomography (CT) scans may be utilized to confirm the diagnosis or rule out other conditions.
Prompt surgical intervention is the standard treatment for appendicitis, usually involving laparoscopic or open appendectomy.
If left untreated, appendicitis can lead to complications like rupture, abscess formation, or peritonitis, which can be life-threatening.
Postoperative recovery is generally smooth, and most patients can resume normal activities within a few weeks after surgery.
It is crucial to seek medical attention promptly if appendicitis is suspected, as early diagnosis and treatment are vital to prevent complications and ensure a successful recovery.

Synonyms include

Appendiceal inflammation
Appendiceal infection
Acute vermiform appendix inflammation
Acute appendicitis
Inflammation of the cecal appendix
Perforation acute appendicitis
Appendix fistula
Appendix disease
Diseases of appendix
Acute inflammation of the appendix
Other diseases of the appendix

Popular search terms for appendicitis ICD-10 CM codes

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Appendicitis diagnosis codes
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