P&C 48- What is endometriosis?

Endometriosis is a condition where endometrial-like tissue grows outside of the uterus, typically on other pelvic or
abdominal organs (ovaries, fallopian tubes, the lining of the pelvis, and even on the bowels or bladder).

Epidemiology

The prevalence of endometriosis is estimated to be between 2% and 10% of women of reproductive age, with a
higher prevalence in women with infertility (30-50%). The typical age of onset for endometriosis is between 25 and
35 years old, but it can occur at any age, even during adolescence.

Etiology & Risk Factors

The exact cause of endometriosis is still unknown, but several theories have been proposed:

 Retrograde Menstruation Theory: One of the most widely accepted theories is the retrograde menstruation
theory, which suggests that during menstruation, some of the menstrual tissue flows back through the fallopian
tubes and into the pelvic cavity, where it implants and grows. This theory is supported by the fact that
endometriosis is more common in women who have a shorter distance between the cervix and the fallopian
tubes.
 Coelomic Metaplasia Theory: Another theory is the coelomic metaplasia theory, which proposes that cells in the
pelvic cavity can transform into endometrial-like cells, leading to the growth of endometrial tissue outside the
uterus.
 Embryonic Cell Rest Theory: The embryonic cell rest theory suggests that during foetal development, some
cells that are meant to form the uterus and other reproductive organs may remain in the pelvic cavity and later
develop into endometrial tissue.
 Immune System Dysfunction Theory: Some researchers believe that endometriosis may be caused by immune
system dysfunction, which allows the growth of endometrial tissue outside the uterus.
 Environmental Toxins Theory: Exposure to environmental toxins, such as dioxins and polychlorinated biphenyls
(PCBs), has been linked to an increased risk of endometriosis.
 Genetic Factors: Endometriosis tends to run in families, suggesting that there may be a genetic component to
the disorder.
 Hormonal Imbalance: Hormonal imbalances, such as high levels of oestrogen, may contribute to the
development of endometriosis.
 Inflammation: Chronic inflammation in the pelvic cavity may lead to the growth of endometrial tissue outside
the uterus.
 Surgery: such as caesarean sections or hysterectomies, may cause endometrial tissue to be transplanted to other
areas of the body, leading to endometriosis.

Other risk factors:

- Starting menstruation early (before age 11)

- Having short menstrual cycles (less than 27 days)
- Having heavy menstrual periods that last more than seven days

Types of Endometriosis
Endometriosis is a complex and heterogeneous disease that can manifest in different ways, leading to various
classifications. The most widely accepted classification systems are based on the location, extent, and severity of the
disease.

i. Superficial Peritoneal Endometriosis

Superficial peritoneal endometriosis is the most common type, accounting for approximately 80% of all
cases. It is characterized by the presence of endometrial implants on the peritoneal surface, which is the
lining of the abdominal cavity. These implants can cause inflammation, adhesions, and scarring, leading to
pelvic pain, dysmenorrhea, and infertility.
ii. Ovarian Endometrioma
Ovarian endometrioma, also known as endometriotic cysts, occurs when endometrial tissue grows inside
the ovaries, forming cysts filled with dark, thick fluid. These cysts can cause pelvic pain, dyspareunia, and
infertility. Ovarian endometriomas are estimated to affect around 20-30% of women with endometriosis.
iii. Deep Infiltrating Endometriosis
Deep infiltrating endometriosis is a more severe form of the disease, characterized by the invasion of
endometrial tissue into the pelvic organs, such as the bowel, bladder, and ureters. This type of
endometriosis can cause severe pelvic pain, bowel obstruction, and urinary symptoms. Deep infiltrating
endometriosis is estimated to affect around 10-20% of women with endometriosis.
iv. Cervical Endometriosis
Cervical endometriosis is a rare type of endometriosis, accounting for less than 1% of all cases. It occurs
when endometrial tissue grows on the cervix, causing abnormal bleeding, pelvic pain, and dyspareunia.
v. Other:
- Rectovaginal endometriosis, which occurs when endometrial tissue grows in the rectovaginal
septum, causing rectal bleeding, pain, and constipation.
- Ureteral endometriosis, which occurs when endometrial tissue grows in the ureters, causing
urinary symptoms and kidney damage.
- Thoracic endometriosis, which occurs when endometrial tissue grows in the lungs or pleura,
causing respiratory symptoms and chest pain.

Pathophysiology

A. Implantation and growth: Endometrial implants grow by proliferation, invasion, and angiogenesis (the
formation of new blood vessels). The development of these blood vessels ensures the implants receive adequate
blood supply and nutrition, allowing them to grow and survive.
B. Inflammation: The presence of endometrial implants leads to chronic inflammation due to the release of
cytokines, chemokines, and growth factors from immune cells. This inflammation contributes to the
development of adhesions, fibrosis, and pain.
C. Neuroangiogenesis: The growth of nerve fibres into endometrial lesions leads to the development of hyper-
innervated tissue, which contributes to pain sensation.
D. Altered hormonal milieu: Endometrial implants produce hormones, leading to imbalances that further stimulate
the growth of implants and contribute to pelvic pain.
E. Immune dysfunction: Women with endometriosis have altered immune responses, including impaired immune
cell function, increased autoantibody production, and altered cytokine profiles.

Signs & Symptoms

 Dysmenorrhea (painful periods)

 Dyspareunia (painful intercourse)
 Infertility
 Dysuria (painful urination)
  Dyschezia (painful bowel movements)
 Heavy or irregular periods
 Spotting or bleeding between menstrual periods
 Fatigue
 Bloating
 Diarrhoea or constipation
 Back pain

Diagnosis/Investigations

Clinical Presentation

 Endometriosis typically manifests during the reproductive years when the lesions are stimulated by ovarian
hormones. Symptoms are usually strongest pre-menstrually, subsiding after the cessation of menses. The
most common presenting symptom is pelvic pain, which may be accompanied by back pain, dyspareunia,
loin pain, dyschezia, and pain with micturition. A significant percentage of women with endometriosis also
present with infertility.

Diagnostic Tests

 Pelvic Examination: A pelvic examination may reveal tenderness, nodularity, or a fixed uterus, which could
suggest endometriosis. However, these signs are not specific to endometriosis.
 Imaging Studies: Transvaginal ultrasound and MRI can be used to identify ovarian endometriomas and
deep infiltrating endometriosis. However, they cannot reliably diagnose superficial peritoneal
endometriosis. The only definitive way to diagnose endometriosis is through laparoscopic surgery, where a
small camera is inserted into the abdomen to visualize and biopsy any abnormal tissue growth
 Serum Markers: CA-125 is a tumour marker that can be elevated in women with endometriosis. However,
its sensitivity and specificity are not sufficient for a definitive diagnosis.

Treatment

The primary goals of endometriosis management are to alleviate pain, slow disease progression, and preserve or
restore fertility.

1. Medical Management: aim to suppress menstruation and reduce inflammation, thus alleviating pain.
o Hormonal contraceptives: Continuous use of combined oral contraceptives, patches, or vaginal rings
can help manage pain by reducing menstrual flow and endometrial implant proliferation.
o Gonadotropin-releasing hormone (GnRH) agonists: These medications suppress ovarian function and
decrease oestrogen production, leading to a pseudo-menopausal state. However, long-term use may
lead to bone density loss.
o Aromatase inhibitors: These drugs block the production of oestrogen, but they are typically used in
conjunction with other hormonal therapies due to potential side effects and limited efficacy.
2. Surgical Intervention: aim to remove endometrial implants, scar tissue, and adhesions.
o Laparoscopy: This minimally invasive procedure allows surgeons to remove or destroy endometrial
implants and scar tissue using heat, electricity, or laser energy).
o Hysterectomy: In severe cases, removal of the uterus, cervix, and sometimes the ovaries may be
necessary to alleviate symptoms. However, this procedure may not guarantee symptom relief and can
lead to premature menopause.
o
References

1.Oats JJN, Abraham S. Llewellyn-Jones Fundamentals of Obstetrics and Gynaecology E-Book. Saintt Louis:
Elsevier; 2015.

2.Giudice LC. Endometriosis. New England Journal of Medicine. 2010 Jun 24;362(25):2389–98.

3.World Health Organization. Endometriosis [Internet]. World Health Organization. World Health Organization;
2023. Available from: https://www.who.int/news-room/fact-sheets/detail/endometriosis

4.NHS. Endometriosis [Internet]. NHS. 2022. Available from: https://www.nhs.uk/conditions/endometriosis/

5.Treatment — Nuffield Department of Women’s & Reproductive Health [Internet]. www.wrh.ox.ac.uk. Available
from: https://www.wrh.ox.ac.uk/research/endometriosis-care-treatment