Endometriosis of the appendix, unspecified depth

This code describes the presence of endometrial-like tissue within the appendix, without further specification of how deeply the tissue has invaded the appendiceal wall. This ectopic tissue can cause symptoms similar to appendicitis, such as abdominal pain, and may be discovered incidentally during surgery or imaging.

This code is appropriate when documentation confirms endometriosis affecting the appendix, but the extent or depth of involvement (e.g., superficial, deep, or involving serosa) is not specified. It is often used when a pathology report confirms appendiceal endometriosis without further detail on its penetration.

• Ensure documentation explicitly states "endometriosis of the appendix" and does not specify depth.
• Do not use if the depth of invasion is known; instead, select a more specific N80.54- subcategory.
• Consider sequencing this code after a code for acute or chronic appendicitis if the endometriosis is identified as the underlying cause or a co-occurring condition.