All About Endometriosis

Endometriosis is very common and a frequent cause of infertility. If you have chronic pelvic pain or difficulty trying to conceive, you may have wondered if you have it yourself.

In the U.S., approximately 7 million women may be affected by endometriosis — that’s about 10% of all reproductive-age women. Endometriosis is especially common in women affected by pelvic pain, with studies showing that up to 80% of women with pelvic pain have endometriosis. It is thought that up to 50% of infertile women have endometriosis.

Let’s dig into what endometriosis is, how it’s diagnosed, and its impact on fertility. We’ll also review the treatment options for pain management and trying to conceive.

Take me to the bottom line

What is endometriosis?

To start, it’s helpful to know about the endometrium — the lining of the uterus. This tissue is hormonally active and grows each month. The endometrial tissue then sheds and comes out as menstrual blood during your period.

Endometriosis is when endometrial tissue ends up growing outside the uterus. The tissue can also implant on other organs and surfaces in the body — we call these “endometrial implants.” The implants are functional, meaning their tissue responds hormonally just as if it were in the usual place within the uterus. This leads to inflammation, bleeding, and changes to your anatomy through scar tissue and adhesions. Endometriosis can implant on any tissue; the fallopian tubes, ovaries, bladder, and bowel are some of the most common places.

Frequent signs of endometriosis are painful periods, painful intercourse, and bladder or bowel issues. Another common symptom of endometriosis is infertility. However, some patients have what is called silent endometriosis — up to 25% of all cases are asymptomatic.

Several risk factors for endometriosis have been identified. A low body mass index (BMI), as well as alcohol use and smoking, are associated with an increased risk of endometriosis. Race may also play a role, as studies show that Caucasian women are more likely to be diagnosed with endometriosis than African American women. Genetics and family history may also play a role; studies show that if you have a first-degree relative with endometriosis, you are six to seven times as likely to be diagnosed with endometriosis yourself.

There are several leading theories about what causes endometriosis, including changes in the flow of menstrual blood and the transformation of certain types of tissue. There is no definitive answer to this question, though.

How is endometriosis diagnosed?

During diagnosis, a staging system is used to grade the severity of the endometriosis. There are four stages, from mild to severe. This helps patients and physicians communicate about the degree of disease. Interestingly, the stage of endometriosis does not necessarily correlate with the degree of symptoms. So someone with stage IV (severe) endometriosis may experience less pain month-to-month than someone with stage III (moderate).

The symptoms of endometriosis can vary widely. Many women with endometriosis experience cyclical pain that fluctuates with their menstrual cycle. Some have more constant pain due to an endometriosis cyst on the ovary. Some only have bladder or bowel symptoms. And others have minimal pain — the endometriosis comes to light only during the infertility workup. That’s why, when talking to your doctor, it’s important to bring up all of your abdominal and pelvic symptoms. I’ve had several patients come in thinking they have gastrointestinal disorders. Then we come to find out their symptoms fluctuate with their menstrual cycle, and they have been suffering from endometriosis on the bowels.

If your doctor suspects endometriosis, they may get clues from a pelvic exam or pelvic imaging. But most endometrial implants cannot be identified that way. Therefore, the current “gold standard” for diagnosis is surgical, often a laparoscopy, where endometrial implants can be observed and biopsied. The benefit of a surgery for suspected endometriosis is not only that we can confirm a definitive diagnosis, but that we can surgically remove the endometrial implants as well.

Why does it cause infertility?

We know that up to half of women with endometriosis have infertility and that monthly pregnancy rates are lower in people with endometriosis than those without. Why does this happen?

There are several ways we think endometriosis may contribute to infertility. First, endometriosis is known to contribute to pelvic adhesions or scar tissue in the pelvis. If this scar tissue involves the fallopian tubes, it can inhibit their ability to pick up the egg after ovulation. Scar tissue on the fallopian tubes can also cause tubal blockage, preventing the movement of sperm or a fertilized egg. The tubes may not even need to be totally blocked to inhibit fertility; inflammation likely plays a role too.

Second, endometriosis may negatively impact the quality of the egg or the embryo. Embryos from patients with endometriosis who undergo IVF develop at a slower pace than those without endometriosis. This poor embryo development may be the result of lower egg quality. Evidence for this comes from studies involving egg donors who have endometriosis. When eggs from these donors are used to create embryos for patients without endometriosis, the embryo quality is reduced and the implantation rates are lower. This suggests that the egg itself has been impacted by endometriosis, and this effect carries through to both embryo development and implantation.

Finally, despite the fact that endometriosis involves endometrial tissue being outside the uterus, it seems that the function of the normal tissue inside the uterus may be compromised as well. Studies show that molecules on the lining of the uterus that allow the embryo to attach and implant may be reduced in women with endometriosis. Other studies have shown altered levels of antibodies and certain types of white blood cells in the endometrial tissue in the uterus in women with endometriosis. These changes may decrease the ability of an embryo to implant in those with endometriosis.

What are the different treatment options?

The treatment of endometriosis is based on the patient’s goals.

For pain control, treatment typically involves suppressing ovulation, which in turn suppresses the hormonal fluctuations that cause pain from endometriosis. The most common medication used for this purpose is oral contraceptives, and they appear to work best for pain control when taken continuously. Other options are progesterone-only contraceptive pills, or GnRH agonists (Lupron) or antagonists (elagolix). However, because these treatments suppress ovulation, they do not work for people who are trying to conceive.

For pregnancy, one treatment option for endometriosis is IUI paired with medications that induce the body to ovulate more than one egg (also known as superovulation, or SO-IUI). This method has higher pregnancy rates than timed intercourse alone. The data is difficult to interpret, though, because most of the studies looked at women who had previously undergone surgical treatment for endometriosis. The lack of clarity is that we don’t know here if it was the surgery or the SO-IUI that improved fertility.

Another option is surgery. Laparoscopy, a minimally invasive surgical procedure, is not only helpful for diagnosis but also when the suspicion of endometriosis is very high and the patient would benefit from surgical removal of the endometrial implants. Laparoscopy may also be chosen if other surgical procedures can be performed at the same time, like removing a cyst from the ovary, removing scar tissue or adhesions, assessing the fallopian tubes, or removing the appendix. There is no evidence to perform laparoscopy for suspected silent endometriosis, as there is no proven benefit.

For stage I/II (mild to moderate) endometriosis, studies show only a slight increase in the monthly pregnancy rate after surgery. In fact, these studies show that you would need to do 12 laparoscopies to result in one additional pregnancy. In patients with stage III/IV (severe) endometriosis, there may be a bigger impact on the monthly pregnancy rate. But there are some drawbacks as well. If the endometriosis is on the ovaries, surgically removing it inevitably reduces the number of eggs. This is a particularly important factor for patients with low ovarian reserve who are considering IVF. For someone experiencing painful symptoms in addition to infertility, or where removal of a cyst may improve surgical access to the eggs, surgery may be the right decision. Otherwise, there isn’t much evidence to suggest that removal before IVF improves outcomes.

IVF on its own is the most efficient treatment option for endometriosis-related infertility. That said, meta-analyses show that patients with endometriosis undergoing IVF tend to have fewer eggs retrieved and lower fertilization rates, implantation rates, and pregnancy rates. So, it’s important to discuss expectations with your doctor before choosing this option.

To wrap up, let’s review the treatment options if you are trying to conceive and facing this decision:

If you are under 35 with suspected stage I/II endometriosis, surgery for endometriosis followed by timed intercourse offers some benefit, but you may be better served by surgery followed by SO-IUI or going to SO-IUI directly.
If you are older than 35 with a more complex fertility case or suspected stage III/IV endometriosis, surgery followed by SO-IUI or IVF is one option, while another reasonable choice is to go straight to IVF.
If you have very severe endometriosis and are considering a repeat surgery, while there may be some benefit in reducing monthly pain symptoms, you will be best served by going right to IVF.

The bottom line

Endometriosis affects about 10% of reproductive-age women and is a leading cause of both pelvic pain and infertility, although 25% of cases are asymptomatic.
The only definitive way to diagnose endometriosis is through laparoscopic surgery, which can also allow for the removal of endometrial implants.
Endometriosis can impair fertility by causing scar tissue and inflammation, damaging egg and embryo quality, and disrupting implantation in the uterus.
Pain from endometriosis is typically treated by suppressing ovulation, but these treatments are not suitable for those trying to conceive.
For infertility, IVF is generally the most effective treatment, especially for older patients or those with severe endometriosis.