Introduction

Endometriosis is a chronic disease where tissue that resembles tissue lining the uterus grows in other parts of the body. This abnormal growth is most commonly seen in the pelvic region and results in inflammation and scar tissue formation that often causes extreme amounts of pain. Approximately 10% of women of reproductive age suffer from this inflammatory disease worldwide, but up to 50% of women experiencing infertility issues suffer from the disease.¹ 

These numbers may in fact be much higher, considering the low rates at which endometriosis is diagnosed due to its variety of symptoms and lack of awareness. Although no current cure exists for endometriosis and the cause of the disease remains unknown, methods to treat its symptoms can be explored. This article aims to explore the treatment options to tackle infertility caused by endometriosis. 

Understanding endometriosis 

Different types of endometriosis

Endometriosis can be grouped into three types depending on which area of the pelvis the abnormal tissue growth is appearing.²

Superficial peritoneal endometriosis

The peritoneal layer is a thin layer of tissue surrounding the pelvis. This common form of endometriosis affects 15-50% of women with the disease. It is considered the least severe form and is categorised by endometrial tissue attaching to this peritoneal layer. 

Ovarian endometrioma

Ovarian endometrioma is the most common type of endometriosis found in women struggling with infertility.³ This type of endometriosis is characterised by dark, brown fluid-filled cysts formed by endometrial tissue in the ovaries. 

Deep infiltrating endometriosis

Deep Infiltrating Endometriosis (DIE) is the most advanced and severe form of endometriosis affecting approximately 20% of all women with endometriosis. DIE can affect multiple or all areas of the pelvis and is characterised by endometrial lesions over 5mm of depth.⁴ 

Common symptoms of endometriosis

As previously mentioned, the symptoms of endometriosis are incredibly variable, which makes the disease difficult to diagnose. Some of the most common symptoms reported are:

• Pain during periods, particularly in the lower pelvic region and lower back 
• Pain during or after sex
• Pain during urination or defecation 
• Heavy blood flow during periods 
• Issues with fertility

Diagnosis of endometriosis

The delay in diagnosis of endometriosis is a prevalent issue, with the average time to diagnosis being 8 years and 10 months from the first GP visit to the official diagnosis. There are many reasons for this delay aside from the variability of symptoms. Symptoms commonly overlap with many other diseases, making the diagnosis an increasing challenge. There is also currently no available non-invasive diagnostic test for endometriosis.

A pelvic exam can be used, where healthcare professionals feel the pelvic region, but this only allows for the detection of very large cysts. An ultrasound can be used to capture images of reproductive organs and can provide evidence of cysts but does not confirm the endometriosis diagnosis. At present, the most common diagnostic tool used is a laparoscopy. This surgical procedure involves the insertion of a laparoscope through a small incision in the pelvis that allows the surgeon to view the pelvic area and possible endometriosis. During this procedure, a biopsy, which is a small sample of tissue, can be extracted for further testing.

Impact of endometriosis on fertility

Although not all women with endometriosis suffer from infertility, a large number of infertile women are diagnosed with endometriosis. There are many ways that endometriosis is thought to contribute to this reduced fertility, but there is a lack of consensus on how exactly this disease causes infertility due to limited research.

The growth of endometrial tissue can distort the anatomy of the pelvis, blocking the fallopian tubes and preventing successful ovulation. In extreme cases, the tissue can be embedded in the ovaries.⁵ This type of blocking could prevent the sperm from successfully fertilising the egg.

Other studies suggest that the quality of the oocytes themselves can be affected, particularly by ovarian endometrioma. Endometriosis is hypothesised to alter important hormones, such as anti-Mullerian hormone (AMH) and luteinising hormone (LH) in a way that negatively impacts fertility.⁶

Regardless of the lack of confirmed cause between endometriosis and infertility, there is an undeniable correlation between the two. The result of this infertility can also have a large negative psychological effect, causing women to feel inadequate and has been reported to contribute to depressive symptoms. 

Treatment options for endometriosis-related infertility

The precise mechanisms by which endometriosis correlates to infertility are still unknown. This makes treatment of endometriosis-related infertility increasingly challenging. However, many treatment options are available and are recommended based on the consideration of individual patient factors, such as:⁷

• Age 
• Severity of endometriosis
• Duration of infertility

Broadly, there are three different types of treatments available:⁸

• Surgery for endometriosis removal
• Medical therapy to alleviate pain symptoms
• Technologies adapted to assist reproduction

Surgical treatments

The most common surgical treatments used are laparoscopy and robotic surgery. Surgical techniques involve the removal of endometriosis-induced damage and cysts in an attempt to restore normal pelvic anatomy. Laparoscopy was previously mentioned as a diagnostic tool, and many surgeons conduct both diagnosis and removal (if necessary) during one surgery. Laparoscopy is the most common treatment method for endometriosis as it is less expensive and involves a shorter recovery time.⁹

Medical treatments

Most medical treatments use hormones, such as:

• Combined oral contraceptive pill
• Progestogens
• Danazol 

These types of treatments are effective in alleviating pain caused by endometriosis but do not improve infertility. In fact, their treatment is often associated with further subfertility.¹⁰ However, other forms of medical treatment have been effective in combating infertility when used in combination with Assisted Reproductive Technology (ART). Medications such as Clomiphene Citrate can be used to boost ovulation prior to treatments such as In Vitro Fertilisation (IVF).⁸ 

Assisted reproductive technology (ART)

ART involves handling sperm, eggs, or both outside of the body to assist with reproduction.¹¹ The most common forms of ART used are intrauterine insemination (IUI) and in vitro fertilisation (IVF).⁹

Intrauterine insemination (IUI)

This technique is commonly used for patients presenting with mild endometriosis and unaffected sperm quality but is not effective for patients with severe forms. In this treatment, ovulation is often primarily induced using medication, and sperm is then inserted directly into the uterus. 

In vitro fertilisation (IVF)

This technique has been shown to be successful in increasing infertility in individuals suffering from all forms of endometriosis. It involves stimulating the growth of many eggs using medications, harvesting these eggs, fertilising eggs outside of the body, growing the fertilised eggs in media for a few days and then inserting the embryos back into the uterus, where they will hopefully implant and grow. 

Success rates of treatment options

The best course of treatment will vary depending on patient factors and choosing the most suitable course of treatment will affect the success of the treatment. For example, for younger women (under 35) with minimal-mild endometriosis, medications to stimulate ovulation in combination with IUI are most effective. However, older patients with more severe forms may require more intense dosages of superovulation and techniques such as IVF. For patients suffering from extreme forms of endometriosis-related infertility, conservative surgical approaches will be the best option for treatment.⁸ Laparoscopy has also shown promising improvements in fertility for women suffering from mild-moderate endometriosis.⁹ 

Studies have shown that approximately 59% of women were able to naturally conceive after surgical treatment of endometriosis.¹²  Surgery can also be used in combination with medical and ART techniques to further enhance the likelihood of success. IVF is currently the most effective treatment method generally for endometriosis-induced infertility.⁸ Even for more severe endometriosis, patients have shown a 40.3% successful birth rate following treatment with IVF.¹³ Medical treatments alone have not shown promise in increasing fertility for women with endometriosis, but have been shown to increase the rates of success of ART treatments specifically. 

Summary

Endometriosis is an unfortunately common and often underdiagnosed disease that negatively impacts women’s fertility rates. Although there is still a lot unknown about endometriosis, such as its precise cause and how it induces infertility, there are still many treatment options available that can increase the likelihood of pregnancy. Conservative surgical treatment such as laparoscopy has shown great promise in both alleviating endometriosis-induced pain and allowing women to conceive naturally. Assisted Reproductive Techniques (ART) have demonstrated high success rates especially when used in combination with medical techniques to induce ovulation. Success rates of each fertility treatment vary greatly and the best way to increase the likelihood of success is to consult a healthcare professional. Healthcare professionals can assess individual factors, such as age and endometriosis severity to recommend the best treatment plan.