Why does endometriosis cause infertility?
According to medical statistics it is estimated that infertility can affect around 40% of women with Endometriosis
Infertility can be one of the consequences of Endometriosis. Women are not only dealing with a debilitating disease but they are also in fear of not being able to have children.
But let’s not paint a gloomy picture here. It is fortunate that not all women who have endometriosis are infertile. (If all women who had endometriosis were infertile then birth rates would drop considerably and a rush to find successful treatment for this disease would, hopefully, be implemented.)
Interestingly, it has been found that between 30 to 40 percent of women undergoing laparoscopy as part of an infertility evaluation are found to have Endometriosis. This is when women are finally diagnosed with the disease by default.
There appears to be a number of mechanisms by which Endometriosis impacts on fertility. Scarring or adhesion's in the pelvis, for example, may cause infertility. The fallopian tubes and ovaries may adhere to the lining of the pelvis or to each other, restricting their movement.
The scarring and adhesions that takes place with Endometriosis may mean that the ovaries and fallopian tubes are not in the right position, so the transfer of the egg to the fallopian tubes cannot take place. Similarly, Endometriosis can cause damage and/or blockage to the inside of the fallopian tube, impeding the journey of the egg down the fallopian tube to the uterus.
Another factor which could cause infertility for women with Endometriosis, may be the over-production of prostaglandins. These are hormones which play and important role in the fertilization and implantation of the embryo. An excess of prostaglandins may interfere with these processes.
Because Endometriosis often causes painful intercourse, couples may fail to have intercourse during the woman’s most fertile time, which will obviously impede the possibility of conception.
A closer look at some of the possible causes of infertility
Abdominal Adhesions and Infertility
As the Endometriosis implants grow and develop in the abdomen, the body tries to surround them with fibrous connective tissue (scar tissue). The body does this in an attempt to isolate the implants and prevent them from doing harm. Adhesions can also be formed during surgery when abdominal tissue is traumatise.
These fibrous growths also have the effect of making the implants stick to adjacent tissue, and in some case organs can be ‘glued’ together. Also the blood from internal bleeding from the implants can forms adhesions, so that an implant may be stuck to several different tissues. For example, an Endometriosis implant on the top of the uterus may cause the ovary and small intestine to become attached at the site of the implant.
If the adhesions caused by Endometriosis pinch off the fallopian tube or if they cause blockage to the opening of the fallopian tube, they could obstruct the merger of egg and sperm and prevent fertilisation and conception. Also ectopic pregnancy is more common with Endometriosis, if the embryo can't travel to the womb. This type of obstruction can be easily diagnosed and surgically corrected.
However, this does not explain how patients with just a few Endometrial implants and no adhesions can become infertile. Adhesions can also cause pain, as internal organs which normally slip and slide are firmly glued together. For example, if the bowel is stuck to a tender, painful ovary, flatulence could cause pain.
Secretions from implants
The normal Endometrium which lines the womb is a very active and vital tissue that secretes a wide variety of nutrients and hormones required for normal conception.
The endometrial implants also secrete these same substances, but instead of depositing them into the lumen (centre) of the womb as normal, the endometrial implants release their chemical secretions into the abdominal cavity. Some of these substances are potent hormones which could interfere with fertility.
One major group of hormones secreted by the normal endometrium is that of the prostaglandins. Prostaglandins are oil-based hormones found in nearly all the tissues of the body and are required for many bodily processes, including several stages of the menstrual cycle and pregnancy.
Prostaglandins are required for ovulation, regression of the corpus luteum (i.e., ending the monthly menstrual cycle), sperm motility, immune interaction, contraction of the uterus at birth and menstrual cramps. Endometriosis implants and the endometrium of the uterus are the richest source of prostaglandin production in the body.
However, the problem with Endometriosis implants includes:
- Prostaglandins are released into the abdomen instead of inside the womb
- Prostaglandins release by the implants seem to be out of phase with their release by the uterus. Prostaglandins are produced at the wrong time sending the wrong message.
For instance, there is a normal surge in prostaglandin F production at the end of the menstrual cycle, causing the effect of the copus luteum of the ovary to die down and signalling the start of a new menstrual cycle. The implants of Endometriosis produce their own prostaglandin surge several days after that of the womb lining. This may be one of the main causes of very early miscarriage.
If a women is a few days pregnant then the Endometriosis implants producing prostaglandin F would incorrectly signal the ovary to start a new menstrual cycle, causing the womb lining with the implanted egg to be expelled - and the consequence is an early miscarriage.
Prostaglandins also play an important role in the contractions of womb and fallopian tubes. During the normal menstrual cycle, the gentle contraction of the womb and fallopian tube aids the movement of egg and sperm to the outer third of the fallopian tube where fertilisation occurs. High concentrations of endometriosis implants may prevent fertilisation. An excess of PGF2 and PGE2 could cause contractions that are too strong and expel the egg too quickly.
The most common time for a miscarriage to occur is during the first three months of pregnancy. During this time, the embryo is developing into a fetus and is undergoing dramatic changes, including the formation of most of its internal organs. This is a critical period of development that requires an appropriate nutrient-rich environment, a healthy placenta and a very delicate balance between the various hormones involved in pregnancy.
However, the real problem of a an early miscarriage, is that if it occurs during the first six weeks of pregnancy there is a good chance that women may not even be aware that they were pregnant. They may think their period was late.
Regardless of whether or not there is a high miscarriage rate in Endometriosis patients, it is imperative to eat the right sort of nutrient-rich food to try to ensure the maintenance of a pregnancy.
Nutrition in both parents, even before pregnancy has a profound effect on the state of the egg and sperm, as well as on the nature of the secretions within the peritoneal cavity. Choice of foods, particularly fats and oils, may be a crucial factor as these affect the production of prostaglandins, cell membranes, steroid hormones, and neurotransmitters etc.
Fertility and the Alert Immune System
In order to achieve pregnancy, sperm has to enter the body. This sperm can be judged as 'alien' by a women's immune cells, because it is 'non-self'. If pregnancy is achieved, the women's immune system has to adapt to the presence of 'alien' tissue growing inside her for nine months.
However, there will be some mechanism in nature, which tells the female immune system that this alien tissue is not a danger, in order to avoid damage to the embryo. Perhaps when the immune system is malfunctioning in Endometriosis, this mechanism fails and causes an immune attack on the embryo and sperm, thought to lead to infertility. Correcting or strengthening the immune system may help to achieve fertility for women with Endometriosis.
Tests for Infertility
For a woman to be fertile, the ovaries must release healthy eggs regularly, and her reproductive tract must allow the eggs and sperm to pass into her fallopian tubes for a possible union.
After your doctor asks questions regarding your health history, menstrual cycle and sexual habits, a general physical examination is done. This includes a regular gynaecological examination. Specific fertility tests may include:
Mayoclinic.org - endometriosis