Endometriosis And Infertility: What You Need To Know

How endometriosis affects fertility

Endometriosis is a chronic inflammatory condition estimated to affect about 10% of women and girls of reproductive age.¹ It can cause painful symptoms during menstruation, sex, and everyday life. 

Sadly, many women with endometriosis struggle with infertility. For some, this may mean they cannot fall pregnant at all, while for others, it is possible but difficult. 

Your endometrial tissue is usually only found in the inner lining of your uterus. In endometriosis, this tissue grows outside the endometrium, in and around organs such as the pelvis, ovaries, and fallopian tubes.²

Due to hormonal influences, the endometrial tissue can thicken and form lesions and cysts because the blood has nowhere to go — unlike in normal endometrial tissue, which is expelled by the vagina during menstruation.³

A direct cause-and-effect relationship between endometriosis and infertility has not been proven, but there is a strong association.⁴ This is likely through a combination of physical, hormonal, and inflammatory processes.

Physical mechanisms

If endometrial tissue grows inside or around a woman’s reproductive organs, it can form scar tissue that blocks the passage of sperm and eggs and fuses organs together, leading to fertility problems. This is more common in women who have severe endometriosis.⁵

For fertilization to happen, a mature egg must be released from the ovaries and into the fallopian tube, where it travels until it is met, penetrated, and fertilized by a single sperm.⁶ This fertilized egg must then travel to the endometrium inside the wall of the uterus, where it will attach itself and begin to grow. 

If there is a blockage along the way, it can make the whole process of fertilization and uterine implantation more difficult.

Some examples of the consequences of a blockage due to endometrial tissue growth include:⁷

Around the ovaries

A mature egg can’t be released into the fallopian tubes, so fertilization will not happen. 

Inside the ovaries

Ovulation may not occur, so the egg will not be released. 

Around the fallopian tubes

The egg and the sperm may not be able to travel through the tube and meet, so fertilization will not happen. If they do meet and fertilization does occur, the egg may be unable to travel through the rest of the fallopian tube and implant in the uterus.

Chronic inflammation

When endometrial tissue grows outside the uterus, it causes inflammation in the surrounding areas.⁸ A type of liquid called peritoneal fluid lubricates the inside of the abdominal wall and pelvic cavity. In women with endometriosis, this fluid contains inflammatory chemicals that cause irritation and lead to pain.

How does this chronic inflammatory response occur?

1. The endometrial cells produce messengers known as inflammatory mediators. These include chemical compounds called cytokines and chemokines. 

2. They attract immune system cells, such as neutrophils and macrophages, to the area. 

3. These immune cells put substances called growth factors into the fluid that bathes the endometrial cells. 

4. This causes the endometrial tissue to grow. 

Studies have shown that this chronic inflammation negatively affects important parts of the reproduction process — such as the:⁸

• Eggs

• Sperm

• Embryo quality

• Hormone pathways

• Ability of the embryo to attach and grow

It is known to: 

• Cause changes to the reproductive organs 

• Damage the DNA of the egg and/or sperm 

• Impair the movement of sperm

• Impair implantation of the fertilized egg into the wall of the uterus 

• Cause a hormone imbalance, with high estrogen and low progesterone levels 

• Impair the maturation and fertilization of eggs, which leads to poorer egg quality and lower numbers of mature eggs 

• Cause rejection of the newly implanted embryo, which may lead to an early miscarriage 

How common is infertility in people who have endometriosis?

Many women with endometriosis can conceive naturally. However, infertility is still quite common. Studies have shown that 30–50% of women with endometriosis struggle with infertility.⁷

The association between endometriosis and infertility is stronger in:

• Women over 35

• More severe cases of endometriosis

• Some reproductive organs affected by endometriosis, such as the fallopian tubes or ovaries 

When should you see a specialist for testing?

If you have endometriosis and are over the age of 35, it is recommended that you see a fertility doctor for testing before beginning any treatments or trying to get pregnant.

If you are younger than 35, you likely have a higher chance of conceiving naturally, depending on the severity of your condition.⁹ In this case, you are encouraged first to try naturally. However, it is recommended that you see a fertility specialist if you have had unprotected sex for six months without getting pregnant.

How will a fertility test be conducted?

The fertility specialist will review your endometriosis history and discuss your goals. They will talk you through the available tests and make sure you understand the process.

You must understand what will happen and feel able to ask your doctor any questions, as the invasive tests can be uncomfortable and may make you feel nervous if you are not sure what to expect.

Blood tests

• Anti-Müllerian hormone (AMH): This tells you how large an egg supply you have remaining. This test can also help to predict how effective in vitro fertilization (IVF) would be.¹⁰

• Follicle-stimulating hormone (FSH): This hormone causes the ovarian follicle to grow into a mature egg that can ovulate. FSH levels will be higher in women with fewer eggs because it has more work to do.¹¹

Laparoscopy and dye test

This is a minimally invasive surgical procedure where a medical device with a camera and light is inserted into the pelvic region. It allows the surgeon to examine the pelvis and reproductive organs for abnormalities associated with endometriosis, such as:

• Ovarian cysts

• Scar tissue

• Overgrowth of the uterine lining

When the dye is inserted through the opening, the surgeon can also see if the fallopian tubes are blocked or if any other abnormalities explain infertility.

Hysterosalpingogram (HSG)

This test can either be carried out with ultrasound or an x-ray.¹² A thin tube is inserted through the vagina and into the uterus, with contrast dye flushed through.

It can be used to examine whether the fallopian tubes are open and if there is scar tissue or fibroids in the uterus that may be causing fertility issues.

Can infertility be prevented?

As there is currently no cure for endometriosis, infertility associated with this condition cannot be prevented.

In addition, infertility can have different causes. Many women with endometriosis also have other issues which impact their fertility.¹³ Even if they could get rid of their endometriosis, other factors may make it difficult for them to conceive.

Can infertility be treated?

Fortunately, infertility can be temporary for women with mild-to-moderate endometriosis. It can be treated in a few different ways, and sometimes, a combination of methods may be used.

You should seek advice from your doctor, who will help you decide the best treatment for your specific situation. This could depend on your age, duration of infertility, endometriosis severity and locations, and any surgery you’ve already had for it.

Unfortunately, although these methods can be highly effective, the success rate of assisted reproductive technologies such as IVF and IUI is still lower in women with endometriosis compared to women without endometriosis.

Evidence-backed ways to treat infertility include:¹⁴

In vitro fertilization (IVF)

This involves fertilizing an egg in a lab rather than the fallopian tube. Mature eggs from the mother and sperm from the father are removed, placed in a Petri dish, and left until fertilization occurs.

The fertilized egg — the embryo — is then implanted directly into the mother’s uterus. This will likely be the treatment of choice¹⁵ if a woman is over 35 or has:

• Multiple infertility factors

• Moderate-to-severe endometriosis

• Blocked fallopian tubes

• Reduced egg production

Intrauterine implantation (IUI)

Healthy sperm is removed from the father and directly inserted into the mother’s uterus during ovulation to allow fertilization to occur.

This treatment is less invasive than IVF, so it may be the treatment of choice when possible. It is used mainly in women with mild-to-moderate endometriosis.¹⁵

Operative laparoscopic surgery

In addition to being a useful diagnostic tool for infertility, laparoscopic surgery can also be used as a treatment. This involves removing the excess endometrial tissue from the area surrounding the uterus or that which is causing obstruction of the female reproductive organs.

This procedure improves fertility by making it easier for the egg to travel through the fallopian tube, meet with the sperm, and implant in the uterus. This treatment is most effective in women with mild endometriosis, although it can also be used for more severe cases.

Surgery can increase the chance of subsequent natural conception, although some women will also require assistive treatments such as IVF. There is a risk of scar tissue forming on reproductive organs with repeated surgery, so you should keep this in mind if you’ve had previous surgeries.

Fertility drugs

Some common fertility drugs are ovulatory stimulants and hormones called ‘gonadotropins.’

It is thought that these drugs do not treat fertility well enough on their own for women with endometriosis. However, they can be very effective when paired with other methods such as IUI.¹⁶

Lipiodol hysterosalpingography (HSG)

In addition to being a useful diagnostic tool for infertility in women with endometriosis, HSG can also be used as a treatment for infertility when a contrast medium, lipiodol, is used for flushing the fallopian tubes during the HSG procedure. This is thought to help the endometrium be more receptive to the implantation of a fertilized embryo.¹⁷

This treatment will only be effective if the fallopian tubes are open, which can be confirmed using a regular HSG or other diagnostic tools.

How can you try to fall pregnant if you have endometriosis?

In addition to the fertility treatments discussed above, there are further recommendations to help increase your chance of fertility.

Try to get pregnant as soon as you are ready to have children

Your ovarian reserve naturally depletes as you age.¹⁸ This may happen sooner if you have endometriosis, especially if you have poorer egg quality. Endometriosis is usually a progressive disease, so the longer you have it, the higher your chance of infertility will be.

Try to get pregnant soon after surgery

You should try to get pregnant in the first 6–12 months after having laparoscopic surgery.¹⁹ This timeframe is believed to be most effective and results in the most successful natural pregnancies.

Freeze your eggs

If you have endometriosis but are at a time in your life when you are not ready to have children, you may be able to freeze your eggs to be used for IVF in the future.¹⁸

Consider your medication

Be aware that some medications commonly used to treat endometriosis symptoms may not improve fertility. The main example is hormone medications that inhibit ovarian function, and these will need to be discontinued if you want to get pregnant.

However, stopping them may negatively impact your endometriosis symptoms. In this instance, it would be good to see a doctor and discuss alternative pain management during this time.

Seek medical advice

Always seek advice from your doctor or fertility specialist before making any lifestyle changes or starting new treatments or medications.

Ensure you do your research using trusted sources and follow evidence-based advice.

The lowdown

Being diagnosed with endometriosis and living with painful symptoms can be difficult. It can be even more challenging for you and your partner if you wish to have children but struggle with fertility due to endometriosis.

Seek advice from a doctor or fertility specialist as soon as you are ready to start trying to get pregnant. You can then receive effective treatment while managing your endometriosis symptoms and improving your pregnancy chances.