Endometriosis and fertility – Dr. Jessica Farren


Similar to PCOS, endometriosis is a common conditions that may influence fertility.  It affects approximately 1 in every 10 women, Often endometriosis doesn’t cause any problems at all – but we explain a little more what impact it could have, and how it can be managed, below.

What is endometriosis?

Endometriosis is a condition in which the tissue of the lining of the womb (the endometrium) is found in other parts of the body, usually around your womb, ovaries and fallopian tubes. This tissue responds to the hormones of your monthly cycle in the same way as the tissue within your womb, i.e. by growing and then shedding and bleeding. Away from the womb, on the surface of the sensitive organs in your pelvis, this causes pain and inflammation – usually just before and during your period. As the inflammation continues, scar tissue can build up and stop the womb, ovaries and fallopian tubes sitting in position and moving freely as they would otherwise. In some women with severe endometriosis, it can involve the wall of the bowel, where it causes bowel symptoms with each cycle.

It’s not known why endometriosis occurs. Some think it is caused by blood flowing ‘backwards’ through the fallopian tubes (retrograde menstruation). However, we know that this is not the whole explanation because all women, including those without endometriosis, have evidence of blood flowing ‘backwards’ into their abdomen if you perform an ultrasound scan during their period. We know that it runs in families, so some of the cause is likely to be in our genes. There are also some theories that it results from your immune system responding differently, or from environmental toxins (sadly we don’t know what!).

Endometriosis and fertility

It is important first to say that the majority of women who have endometriosis do not experience any unwanted delays to becoming pregnant.

Evidence has however shown an association between infertility and endometriosis. Minimal to mild endometriosis sufferers have an almost normal chance of conception, but some sufferers experience delays for reasons that are not fully understood. The more severe the endometriosis, the lower the chances of natural conception. This is likely to reflect a greater amount of inflammation and scar tissue, which may affect the way eggs are released from the ovaries, or how the fallopian tubes carry the fertilised egg into the womb.

Keyhole surgery to treat endometriosis can improve the chances of getting pregnant naturally. This surgery (also known as laparoscopic surgery) is used to remove endometriosis and scar tissue (called ‘adhesions’ – which can cause organs to stick together), or collections of blood caused by endometriosis in the ovaries (known as endometriomas). The decision over whether or not to remove endometriomas is often a difficult one. This is because it is difficult to remove large endometriomas without damaging some of the surrounding healthy ovary. This may then have a negative effect on ovarian reserve (i.e. the number of eggs you have), which in turn may affect the number of eggs that can be collected at IVF (though probably wouldn’t have a negative effect on natural conception).

If there is severe scarring, or you don’t get pregnant naturally after treatment, IVF may be recommended.

if you have symptoms suggestive of endometriosis and are experiencing unwanted delays to conception (perhaps after trying for 6 months), then you may prefer to see a fertility doctor sooner than the 12-24 months the NHS would usually recommend. They will be able to arrange some tests to assess for any endometriosis (usually an ultrasound first), and whether it might have had an impact on your fallopian tubes.

Endometriosis and pregnancy

If the fallopian tubes are scarred, there is a higher risk of an ectopic pregnancy (a pregnancy sitting in the tubes, which cannot continue, and can be dangerous). If you know you have tubal scarring, you may be advised to have a scan at 6-7 weeks of a pregnancy to check it is in the right place (earlier if you have pain or bleeding).

Endometriosis does not increase your risk of miscarriage or complications later in pregnancy. A healthy pregnancy will also often settle symptoms of endometriosis (as you don’t have a cycle for nine months – more if you choose to breastfeed!).

Other implications of endometriosis

If unchecked, endometriosis can cause scar tissue to progressively build up over time. This can cause chronic abdominal pain (i.e.not just during your period) and painful sex. If you are not trying to get pregnant, then you may wish to consider hormonal treatment (often contraceptive pills), which helps to calm the endometriosis down.