Deep Ovarian Endometriosis (Endometriomas)

Endometriosis can be present in the form of classic implants located on the surface of one or both ovaries but it can also be found deep within them. Deep ovarian endometriosis forms dark fluid-filled cavities that can vary in size known as endometriomas or "chocolate cysts". The diagnosis of an endometrioma may be suspected based on ultrasound imaging of the pelvis, but the final diagnosis must be based on microscopic examination of the cyst itself. (see below).

Endometriomas may be considered the most serious threat to a woman’s reproductive potential, with the exception of cancerous tumors of the reproductive tract. These lesions respond very poorly to medical treatment and have the potential to destroy all of the healthy ovarian tissue, leading to premature or early ovarian failure, problems with ovulation or decreased ovarian function. Endometriomas can also lead to invasive and destructive pelvic surgeries, which can cause partial or complete premature loss of ovarian function. These cysts can represent a medical dilemma even while women are receiving fertility treatments such as assisted reproductive technologies (ART).

Clinical Impact of Endometriomas (in Women of Reproductive Age)

Endometriomas may:

  • Place a woman of reproductive age at a higher risk for ovarian cancer
  • Cause pelvic pain
  • Contribute to infertility
  • Decrease ovarian function
  • Interfere with assisted reproductive technologies

Treatment Options for Endometriomas (in Women of Reproductive Age)

Not all health care providers agree on one single treatment when managing endometriomas; however, most experts believe that women of reproductive age should be treated by fertility specialists.

  • Observation of symptoms
  • Observation by ultrasound
  • Medical treatment
  • Surgical treatment - biopsy, drainage and coagulation of the cyst; stripping of the cyst from the ovary; partial cyst stripping and laser ablation


Oophorectomy (removal of the ovary containing the endometrioma) is never an option in women of reproductive age with symptoms that suggest an endometrioma.

Although less than one percent of ovarian cysts diagnosed as probable endometriomas by ultrasound in women of reproductive age turn out to be malignant tumors, the possibility still exists. Generally, if an ovarian cyst looks like an endometrioma on ultrasound, and persists and is greater than > 4 cm (by current standards) surgery is necessary to rule out a malignant tumor. Surgery is also indicated when severe chronic pelvic pain is present.

Observation and medical management usually are not usually effective in providing relief of symptoms associated with endometriomas. Conservative surgery on the other hand is very effective in providing lasting relief. Surgical “excision” or removal of the endometrioma(s) is also an effective fertility-enhancing surgery in young women suffering from infertility with no other apparent cause (and that are not committed to assisted reproduction). A large research study reported a pregnancy rate of over 50 percent within two years of surgery to remove the endometrioma in women who participated in the study.

Removal of endometriomas is not recommended in women planning to undergo ART (in vitro fertilization). Surgical removal has no beneficial effect on pregnancy rates and can decrease the ovarian output of eggs in this setting (depending on the surgical technique used). However, there are rare situations in which endometrioma surgery is recommended, even in women undergoing ART. These include the following:

  • Endometrioma substantially impairs the retrieval of the eggs
  • Endometrioma is ruptured or infected at the time eggs are retrieved
  • Adequate ovarian stimulation for ART causes severe pain
  • Endometrioma has suspicious radiologic features (malignancy suspected)

Surgery remains the mainstay of modern management of endometriomas. However, how much surgery (which technique is employed) and when it is offered can make a dramatic difference in the ultimate success of treatment. There is no question that even minimally invasive, conservative, standard techniques for the excision of an endometrioma can result in permanent damage to the ovary. The Boston Center for Endometriosis is a highly specialized multidisciplinary center and a leader in technological innovation to explore new ways to treat this challenging condition (also see our section on computer-assisted reproductive surgery). Our goal in treating endometriomas is to preserve fertility while providing safe and quality of life treatments that will enhance reproductive success.

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