There are two theories about how endometriosis develops:

One is that endometrial cells, which are shed during menses, egress out the fallopian tube and into the abdominal cavity where they grow. Immune cells normally prevent their growth, but in women with endometriosis, this immune response is impaired.

The other theory is that there are cells inside the abdominal cavity that simply differentiate abnormally into endometrial cells. However it forms, the endometrial cells trigger an inflammatory response. It is the inflammatory response in the pelvis that can cause pain, infertility, scar tissue formation, adhesions and bowel problems.

Endometriosis typically occurs in the pelvic area on the ovaries, on fallopian tubes and ligaments that support the uterus, on the area between the vagina and rectum, and along the lining of the pelvic cavity. Symptoms are quite variable and the severity of symptoms do not correlate with the extent of the disease.

An estimated six percent of women have endometriosis and the incidence may be 12-15% in women who have infertility. Endometriosis may have a genetic component as there is an about 6-fold increased incidence in women with an family history of endometriosis in a mother or sister. Endometriosis can grow under the influence of estrogen and typically regresses when women enter menopause.


The two major symptoms of endometriosis are pain and infertility. Symptoms of endometriosis-related pain may include:

  • Painful, disabling cramps during menses
  • Pain with mid-cycle ovulation
  • Pain with intercourse
  • Pain with urination
  • Abdominal pain association with constipation and /or diarrhea

Many women have no symptoms of pain but have difficulty conceiving. Suspicious signs of endometriosis when there is no pain include:

  • Ultrasound evidence of persistent ovarian cysts
  • An abnormal pelvic exam where the uterus is fixed in retroverted or “tipped “ position”
  • A rectal exam in which endometriosis can be palpated behind the uterus

How endometriosis affects fertility

There are primarily two ways that endometriosis affects fertility:

  • Inflammation: This means that the immune cells in the pelvic cavity are activated. In the fluid that baths the pelvic cavity, an increased concentration of products of the immune cells, such as cytokines are found. It is thought that these inflammatory hormones may interfere with fertilization or early embryo development. So there is an unfavorable environment for fertility.
  • Scar tissue: As part of the inflammatory response, scar tissue forms between the tubes and ovaries. This can result in the alterations in the normal anatomical relationships between the tubes and ovaries, which can result in difficulty conceiving.


Endometriosis may be suspected based on a woman’s symptoms, pelvic exam or pelvic sonogram. There is no good imaging technique for diagnosing endometriosis but on ultrasound, ovarian cysts (called endometriomas or “chocolate cysts”) have a characteristic appearance and are sometimes the first clue that a woman has endometriosis.  Smaller implants of endometriosis cannot be imaged with ultrasound, MRI or CT scan.

The only means to make a definitive diagnosis of endometriosis is by laparascopy in which the endometriosis lesions can be seen directly and biopsied. At the time of laparoscopy, the diagnosis of endometriosis can be confirmed, the extent of the disease can be ascertained and the patient’s prognosis can be established. At the same time, the endometriosis can be removed, improving the chances of conception and decreasing the severity of pain. Knowing that endometriosis exists and how severe it is can help the patient make appropriate choices for future treatment if needed.


There are two options for treating infertility due to endometriosis: surgery or IVF

  • For Minimal and Mild Endometriosis: Some studies show surgical treatment of endometriosis results in improved pregnancy rates. Other studies show equal efficacy of use of fertility medications for ovulation induction with intrauterine insemination.
  • For Moderate to Severe Endometriosis: In-vitro fertilization (IVF) is the most effective treatment. Because the eggs and sperm are removed from the unfavorable environment of endometriosis, there is no negative impact of endometriosis on fertilization and early embryo development.

There is no consensus on the benefit of removing endometriomas before IVF. There are studies that show no negative impact of endometriomas on IVF outcome so surgery is not necessary. With surgery, there is some concern about resection of endometriomas and the risk of destroying normal ovarian function. However, if an endometriomas is growing then the endometriosis can destroy normal ovary and decrease a woman’s chance of conceiving even with IVF.

Robotic surgery

With the robotic laparoscopy approach, endometriomas can be resected more completely decreasing the risk of recurrence. In addition, with robotic assisted laparoscopy, suturing can be used instead of electrocoagulation, which can decrease the risk of destroying normal ovary.

The decision when to apply surgery or IVF in endometriosis-associated infertility needs to take into account several factors:

  • age of the patient
  • ovarian reserve testing
  • progression and severity of the endometriosis
  • the presence of other infertility factors
  • duration of infertility
  • past treatments
  • whether or not there is pain

Generally, surgery for endometriosis is used as a first line treatment and not repeated. If treatment of endometriosis surgically fails, then IVF is the next line of treatment.

Endometriosis can progress and recurs at a rate of 20 to 40 percent within five years following conservative surgery. Periodic pelvic exams and sonography are means to monitor recurrence of endometriosis.

There is no cure for endometriosis but since it is an estrogen responsive disease, hormonal treatment to ameliorate the symptoms is possible. Medical treatment suppresses ovulation.  For treatment of pain due to endometriosis and for women who do not wish to become pregnant the options are surgery or medication.

Experience counts

Experience does count in surgery in order to reduce recurrence of disease. The more experienced the surgeon, the more likely she will recognize and skillfully remove all disease, reducing the risk of recurrence.