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Endometriosis of the Appendix

by Tamer Seckin, MD | Posted on July 13, 2020

What is appendiceal endometriosis?

Endometriosis is defined as the growth of tissue resembling the endometrium outside the uterus. This usually occurs in or around the reproductive organs. However in rare cases, the disease can spread to the bladder, kidneys, lungs, and/or bowels, including the appendix.

How common is endometriosis of the appendix?

It is not known how common endometriosis of the appendix is, and there is great variation in the rate of appendiceal involvement with numbers ranging from 1 to 22 percent.

endometriosis in appenix
Endometriotic implant on the appendix.


Why does endometriosis affect the appendix?

The exact cause of endometriosis is not known, and it is also not known why the disease sometimes spreads to other areas such as the kidneys, diaphragm, or appendix. One hypothesis is retrograde menstruation where the menstrual blood carrying endometrial debris flows backward into the fallopian tubes and subsequently implants and forms lesions [2].

Other theories include [1]:

  • The coelomic metaplasia theory, which suggests that the peritoneal cavity—or the space within the abdomen that contains the intestines, stomach, and liver—houses progenitor cells or cells capable of differentiating into endometrial tissue in response to a specific signal.

  • The induction theory, which suggests that the endometrium, or uterine lining which is shed during menstruation, produces substances to form endometriosis.

  • The cellular immunity theory, which suggests that alterations in the immune system allow endometrial cells to grow outside the uterus.


What symptoms could signal appendiceal endometriosis?

Appendiceal endometriosis can cause a wide range of symptoms that mimic symptoms of acute appendicitis which include a sudden pain that begins on the right side of the lower abdomen and that worsens with movement, loss of appetite, nausea, vomiting, abdominal bloating, constipation or diarrhea, and fever [3]. However, unlike acute appendicitis, endometriosis of the appendix usually causes pain that comes and goes with the menstrual cycle[1].

Are there different types of appendiceal endometriosis?

Patients who have appendiceal endometriosis can be divided into four groups depending on their symptoms [1]. They may experience:

  • the symptoms of acute appendicitis

  • appendiceal invaginations

  • abdominal colic, nausea, and melena, or black stools

  • no symptoms


How can appendiceal endometriosis be diagnosed?

It is difficult to diagnose endometriosis of the appendix because the symptoms are very similar to those of acute appendicitis.

One of the most important tools for diagnosing endometriosis of the appendix is a physical examination. However, imaging techniques such as CT scans can also help diagnose the condition. The surest method for a definitive diagnosis, however, is laparoscopic surgery [1].

Importance of early diagnosis

It is very important that the endometriosis of the appendix is diagnosed early so that the disease can be treated appropriately. If left untreated, appendiceal endometriosis can lead to bleeding or perforation in the intestines and obstruction of the bowels [1].


How is appendiceal endometriosis treated?

An appendectomy (the surgical removal of the appendix) is the best way to treat appendiceal endometriosis. In more severe cases, an ileocecectomy (the surgical removal of the ileum, a part of the small intestine) or hemicolectomy (the removal of a segment of the colon) may be necessary [4].

New research

An interventional clinical trial (NCT01921634) is currently recruiting an estimated 100 participants at Penn State Milton S. Hershey Medical Center in the U.S. to assess whether the incidence of appendiceal endometriosis is related to the method of pathologic analysis [5].

The rate of appendiceal involvement of endometriosis varies greatly, ranging from 1 percent to as high as 22 percent. Researchers hypothesize that the way in which the specimen is analyzed could partly explain this wide disparity. This clinical trial will investigate how the method of pathological analysis influences the incidence of appendiceal endometriosis.

Women aged 18 to 51 who have their appendix removed at the time of laparoscopy to treat their endometriosis and/or pelvic pain are eligible to take part in the study.

Patient Story

A Endo

"Being a freshman in college was enough stress, the last thing I needed was this disease bringing me down. Together, Dr. Seckin, my parents, and I decided surgery was the best option. Going in with no guarantee of success I put all my trust in Dr. Seckin knowing I was in good hands. I am happy to say that now, two weeks after my surgery I feel GREAT! Dr. Seckin removed 15 suspicious adhesions and a very fatty, unhealthy, inflamed appendix. Aside from expected soreness from the surgery, I am confident that I am on the right track back to my old self. " –Anessa Marinello

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  1. Acute appendicitis caused by endometriosis: a case report, Styliani Laskou,Theodossis S Papavramidis, Angeliki Cheva, Nick Michalopoulos, Charilaos Koulouris, Isaak Kesisoglou, and Spiros Papavramidis 
  2. What causes endometriosis?, Tamer Seckin, MD
  3. Appendicitis, Mayo Clinic
  4. Endometriosis of the appendix: Report of three cases, Abdulaziz Saleem, Paula Navarro, John L. Munson, and Jason Hallc 
  5. Endometriosis and the Appendix - Incidence and Pathologic Analysis, Andrea Benton, MD, Milton S. Hershey Medical Center

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You may call us at (646) 960-3080 or have your case reviewed by clicking here.


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