Can Endometriosis Affect the Appendix?
When you live with endometriosis, a different pain can leave you with questions. Is it a familiar flare, a digestive problem, or something that needs a fresh look? The appendix is one location that may not come to mind.
Yes—endometriosis can affect the appendix. This is called appendiceal endometriosis. Understanding it can help you ask informed questions, while remembering that symptoms alone cannot tell you what is causing your pain.
Three things to know before you read on
Appendix involvement can be difficult to identify before surgery.
Pain does not have to follow a menstrual pattern.
New, persistent or worsening pain deserves assessment—even with a known endometriosis diagnosis.
The key message: new, persistent or worsening abdominal pain deserves medical assessment—even if you already live with endometriosis.
A small organ that can raise big questions
The appendix is a small, finger-shaped pouch attached to the beginning of the large bowel. It is usually in the lower right side of the abdomen (belly).
Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside the uterus. When it involves the appendix, it may be found on its outer surface or within its wall. Some people have no symptoms and learn about it only after surgery. [1, 2]
Does appendix endometriosis have a telltale symptom?
Reported symptoms include recurring or persistent pain in the lower right abdomen. Some people have symptoms that resemble appendicitis. Pain may occur around periods, but it does not have to follow a menstrual pattern. A published case, for example, described months of constant right-sided pain. [1, 2]
Pain, nausea and digestive changes have many possible causes. Symptoms alone cannot tell you whether endometriosis is affecting your appendix.
When should you seek urgent care?
Go to an emergency department for severe abdominal pain. Call 911 if you are seriously unwell or cannot get there safely. Do not wait for an endometriosis appointment.
Get urgent medical assessment for pain that is getting worse, does not go away, or moves toward the lower right abdomen—especially with fever, vomiting or loss of appetite. Appendicitis does not always cause the classic symptoms. You do not need to have every symptom to seek help. [3]
Other conditions can also cause similar pain, including an ovarian cyst, kidney stones or an ectopic pregnancy. Tell the healthcare team if pregnancy is possible. Having endometriosis does not rule out another urgent problem. [3]
Why getting an answer can take more than a scan
A clinician will ask about your symptoms and medical history and examine you. Depending on the situation, assessment may include blood and urine tests, a pregnancy test, ultrasound or CT imaging. The immediate priority with new pain is to check for urgent causes. [3]
Appendiceal endometriosis can be difficult to identify before surgery. Confirmation usually comes from a pathologist examining a removed appendix under a microscope. This laboratory assessment is called histopathology. A 2020 study found that examining more sections of the appendix detected additional cases. [4]
A scan that does not show appendix endometriosis cannot reliably exclude it. In a 2024 study of people having urgent appendix surgery, clinical findings and blood tests did not clearly distinguish those with appendix endometriosis from those without it. [1]
Does everyone with endometriosis need their appendix removed?
No. An endometriosis diagnosis alone does not mean you automatically need an appendectomy—the operation to remove the appendix.
If you are planning endometriosis surgery, ask whether the appendix will be assessed and under what circumstances removal would be considered. Discuss your symptoms, the surgeon’s findings, the possible benefits and risks, and your preferences before surgery. Studies have examined removal during endometriosis operations, but they do not establish that every patient needs it. [5]
If your appendix is removed, ask for the pathology results and a follow-up plan. Removing an affected appendix does not treat endometriosis elsewhere, and it cannot guarantee that all abdominal or pelvic pain will resolve.
Questions to take to your appointment
What other causes of my right-sided abdominal pain need to be assessed?
Could appendix involvement be relevant to my symptoms?
If I am having surgery, will you assess my appendix?
What would make you recommend removing it, and what are the risks?
If it is removed, how will I receive the pathology results?
What is the plan if my pain continues?
Finding the words when your pain feels different
“This pain is new or different from my usual symptoms. It started ___, is located ___, and is getting ___. I also have ___. I have known or suspected endometriosis, but I would like other causes assessed too.”
For recurring symptoms, note where the pain occurs, how long it lasts, any connection to your cycle, and changes in appetite or bowel habits. Bring previous imaging, surgery or pathology reports if you have them. Tracking should never delay urgent care.
You deserve to have changes in your pain taken seriously
Learning about appendix involvement can help you ask informed questions. It cannot diagnose the cause of your pain. New symptoms deserve a fresh assessment.
Explore our Canadian care directory for help preparing your next steps. The directory is not an emergency service.
Sources and further reading
Evidence note: studies of people having surgery do not tell us how common appendix involvement is in everyone with endometriosis. Case reports describe individual experiences and cannot predict another person’s outcome.
Prepared by Endometriosis Canada • November 1, 2026. For general education; this article does not replace individual medical assessment.
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