Acute appendicitis without mention of peritonitis

This code signifies an acute inflammation of the appendix that has not progressed to involve the peritoneum. It represents the early stages of appendicitis where the infection is localized to the appendix itself.

Use this code for patients presenting with classic symptoms of acute appendicitis (e.g., right lower quadrant pain, nausea, vomiting, fever) where imaging (e.g., ultrasound, CT scan) or surgical findings confirm appendiceal inflammation without evidence of rupture or peritonitis. Documentation should clearly state "acute appendicitis without peritonitis" or similar.

• Differentiate from 540.0 (acute appendicitis with generalized peritonitis) and 540.1 (acute appendicitis with peritoneal abscess) based on documentation of peritonitis.
• If the documentation is unclear regarding peritonitis, query the provider for clarification.
• This code is often a principal diagnosis for appendectomy procedures.