Endometriosis is often thought of as a disease of the reproductive organs, but it can affect far more than the uterus.
The condition occurs when tissue similar to the lining of the uterus grows outside the womb.
It most commonly affects organs within the pelvis, including the ovaries and fallopian tubes, as well as the bowel, bladder and urinary tract.
In rare cases, it may occur in distant sites such as the diaphragm and lungs.
Consultant gynaecologist Dr Sharifah Halimah Jaafar notes that out of the approximately 500 endometriosis cases operated on at her hospital, around 40% involved organs beyond the reproductive system.
How it develops
Endometriosis begins with the endometrium – the tissue that lines the inside of the uterus.
Dr Sharifah explains that each month, the endometrium thickens in response to hormonal changes and develops a rich blood supply in preparation for pregnancy.
“If pregnancy does not occur, the tissue sheds during menstruation,” she says.
In endometriosis, however, tissue similar to the endometrium is found outside the uterus, where it does not belong.
These growths most commonly occur behind the uterus, on the ovaries and on the fallopian tubes, although they can also be found on organs outside the reproductive system, as mentioned above.
Although located outside the uterus, this endometrial-like tissue continues to respond to female hormones and undergoes the same monthly cycle as the endometrium.
As a result, they shed and cause bleeding during menstruation.
Because this tissue is located in places where it does not belong, the body responds with inflammation.
As this process repeats month after month, the inflammation becomes chronic.
“This ongoing inflammation is one of the reasons many women with endometriosis experience severe menstrual pain,” Dr Sharifah says.
“It can also lead to fibrosis, or the formation of scar tissue.”
Over time, the scar tissue thickens and may develop into large nodules.
In more advanced cases, the disease can cause organs and surrounding structures to adhere to one another.
The ovaries may develop blood-filled cysts known as ovarian endometriomas (chocolate cysts), while the bowel can become attached to endometriosis nodules.
As scarring progresses, pelvic organs – including the ovaries, bladder, uterus, ureters and bowel – may become stuck together.
In severe cases, this can result in a “frozen pelvis”, where the organs fuse into a single mass and lose their normal mobility.
“This can have a significant impact on a patient’s quality of life and cause debilitating pain,” Dr Sharifah says.
Varying symptoms
The symptoms of endometriosis vary from woman to woman, and do not always reflect the severity of the disease.
Although endometriosis is classified into different stages, Dr Sharifah says some women with severe disease may have no symptoms at all.
That said, severe period pain (dysmenorrhoea) remains the most common symptom, affecting about 90% of women with the condition.
“This pain is much more intense than normal period pain,” she explains.
When endometriosis affects the bowel, women may experience pain during bowel movements, as well as constipation, especially during menstruation.
Some may also develop diarrhoea or difficulty controlling their bowel movements.
If the disease penetrates deeper into the bowel, it can cause bowel obstruction, which may gradually block the bowel over time.
The effects are not limited to the digestive system.
The impact of endometriosis can extend to the urinary system, including the ureters, says Dr Sharifah.
“When endometriosis affects the ureters, scar tissue can gradually narrow or block these tubes, preventing urine from flowing properly from the kidneys to the bladder.
“If left untreated, this can lead to kidney damage, and in severe cases, affect one or both kidneys,” she says.
As a result, women with ureter involvement may experience urinary symptoms, including pain during or after urination, difficulty controlling urination, and occasionally, blood in the urine.
Dr Sharifah explains that in rare cases, endometriosis can also spread beyond the pelvis and affect the diaphragm and lungs.
“Women with thoracic endometriosis may experience symptoms that coincide with their menstrual cycle, such as chest pain or shortness of breath, because the lesions continue to respond to hormonal changes,” she says.
The disease can also affect the nerves, which is considered one of the more severe forms of endometriosis.
“When nerves are involved, women may experience numbness in parts of the leg during menstruation, difficulty walking, severe nerve pain, or intense pain around the anus and rectum,” she says.
Dr Sharifah points out that: “Endometriosis can affect the entire body because it may involve multiple organs and systems.”
Surgery for severe cases
Patients with deep-infiltrating endometriosis often require a personalised treatment approach, especially when multiple organs are involved.
To determine the location and extent of the disease, doctors typically begin with an ultrasound examination.
Ultrasound is effective at detecting lesions affecting various pelvic organs, with a standard gynaecological scan focusing primarily on the uterus and ovaries.
However, a detailed endometriosis ultrasound requires specialised expertise and is not routinely performed by all clinicians.
“If ultrasound findings are inconclusive or insufficient, we rely on magnetic resonance imaging (MRI),” says Dr Sharifah.
MRI is also routinely performed before surgery as it allows doctors to carry out surgical or endometriosis mapping.
This helps them determine the precise location and extent of the disease.
While medications can help control pain and inflammation, they cannot remove established endometriosis lesions or reverse advanced disease.
In such cases, minimally invasive or robotic surgery may be required.
“The aim of surgery is to restore the pelvic anatomy and organ function,” says Dr Sharifah.
When the bowel is involved, the surgical approach depends on how deeply the disease has penetrated the bowel wall:
- Superficial disease (C1): A shaving procedure is used to remove lesions affecting the outer layer of the bowel while preserving the bowel itself.
- Deeper disease (C2): When endometriosis extends into the bowel muscle, a discoid resection may be performed to remove the affected portion of the bowel wall.
- Advanced disease (C3): Larger lesions that narrow the bowel or cause obstruction may require segmental bowel resection to remove the affected section of bowel.
Complex cases usually require a multidisciplinary team comprising endometriosis surgeons, colorectal specialists, urologists and other healthcare professionals.
Dr Sharifah explains: “If a colorectal surgeon is not part of the team, patients may not receive the treatment they need.
“As a result, the disease can continue to progress, leading to bowel complications and other serious problems.”
Reducing recurrence
Following surgery, the focus shifts to reducing the risk of recurrence.
Dr Sharifah says that one of the proposed mechanisms behind endometriosis is retrograde menstruation, where menstrual blood flows backwards into the pelvic cavity.
Women with heavy menstrual bleeding may be at greater risk of this occurring.
“Therefore, one of the goals after surgery is to reduce menstrual flow,” she says.
For this reason, patients are often prescribed hormonal therapy after surgery.
“Hormonal treatment helps reduce or suppress menstruation, thereby lowering the likelihood of disease recurrence,” she explains.
The aim is to give the pelvis, uterus and ovaries time to heal before normal menstrual cycles resume.
In some cases where the disease is severe and surgery has been complex, doctors may temporarily stop menstruation for three to six months using gonadotropin-releasing hormone (GnRH) therapy.
This may be followed by hormone pills or a hormonal intrauterine device (IUD) for women who are not planning a pregnancy.
The goal is to keep the disease under control for as long as possible.
Ideally, doctors hope to prevent recurrence for at least five years, and preferably longer.
Dr Sharifah notes, “If the disease does return, the hope is that it represents new disease rather than residual disease left behind after surgery.”
She also recommends lifestyle modifications as part of endometriosis management.
Many women with the condition develop muscle tension and spasms due to chronic inflammation.
Activities such as yoga may help reduce muscle tightness, cramping and pain.
“While lifestyle changes cannot cure endometriosis, they may play an important role in managing symptoms and supporting recovery,” she says.
