Endometriosis vs Ovarian Endometriomas

When we talk about Endometriosis not showing up on imaging, we don’t always clarify that we are referring to Endometriosis lesions, and someone inevitably says their Endometriosis was seen on an MRI or Ultrasound. Then they will elaborate that it was an Endometrioma, not Endometriosis lesions. This is an important distinction so that we are all on the page – because we want to be clear that Endometriosis lesions can only be definitively diagnosed via surgery and pathology. Even still, Endometriomas can evade imaging, mine did!

Regarding Endometriosis of the ovary by Dr. Jeff Arrington::

“The most significant ovarian involvement is an endometrioma. Endometriomas occur when surface ovarian endometriosis lesions start to push into or invaginate into the ovary and then close over the top, forming a cystic mass lined by endometriosis tissue. Endometriomas are also called “chocolate” cysts. The presence of an endometrioma has significant implications as to the extent of Endometriosis and to the potential impact on ovarian function and fertility.” (1)

Endometriomas indicate deep disease, and it is crucial that an expert thoroughly inspects for additional Endometriosis if an Endometrioma is found – even if Endometriosis isn’t initially seen during surgery. Like all Endometriosis, Endometriomas must be meticulously excised from the ovary. A simple draining will not resolve an Endometriomas, and it will very likely continue to “come back.”
We hear this a lot:
“My Endometriosis came back in just a few months.” Was it Endometriosis or an Endometrioma? The distinction is crucial.

“Excision of the endometriosis cyst – or cystectomy – is the process of actually removing the wall of the cyst (the functional part of the endometrioma). This is the part that produces the chocolate-like fluid.” (1)

“Simple drainage of an endometrioma releases the non-active fluid, but leaves the actual endometriosis tissue in place, untreated. Some surgeons will attempt to burn or cauterize the cyst wall with hopes that it will destroy the active tissue of the endometrioma. The perceived benefit of this approach is release of the fluid while minimizing the risk of damaging normal ovarian tissue. Endometriomas treated this way have a high rate of recurrence.” (5)

Sources::

1. Arrington, Jeff. “Ovarian Endometriosis.” The Center for Endometriosis Care, Mar. 2020, centerforendo.com/ovarian.

2. Redwine DB. Ovarian endometriosis: A marker for more severe pelvic and intestinal disease. Fertil Steril 1999;73:310-15.

3. Charles Chapron, Pietro Santulli, Dominique de Ziegler, Jean-Christophe Noel, Vincent Anaf, Isabelle Streuli, Hervé Foulot, Carlos Souza, Bruno Borghese, Ovarian endometrioma: severe pelvic pain is associated with deeply infiltrating endometriosis, Human Reproduction, Volume 27, Issue 3, March 2012, Pages 702–711, https://doi.org/10.1093/humrep/der462

4. Redwine, David B. 100 Q & A About Endometriosis (9780763746391). Jones and Bartlett Publishers, 2008.
5.Vercellini et al. Surgery for endometriosis-associated infertility: a pragmatic approach. Hum Reprod. 2009 Feb;24(2):254-69.