Introduction: What is endometriosis?

Endometriosis is a disease characterized by the presence of a tissue resembling the endometrium (the lining of the uterus) outside the uterus (WHO, 2018). It causes a chronic inflammatory reaction that may result in the formation of scar tissue or lesions (adhesions, fibrosis) within the pelvis and other parts of the body. The lesions can be peritoneal lesions, superficial implants or cysts in the ovary, or deep infiltrating disease (Nisolle and Donnez, 1997). While there is no definitive etiology of endometriosis, there are several hypotheses regarding how endometriotic lesions develop. Endometriosis affects 10% (190 million) of women of reproductive age worldwide (WHO, 2021) and 17% of women with chronic pelvic pain (Armour et al., 2020). Fawole et al in 2019, reported the prevalence of endometriosis amongst asymptomatic women at 48.1% in Nigeria.

Unfortunately, for many of these women, there is often a delay in diagnosis of endometriosis resulting in unnecessary suffering and reduced quality of life. In patients aged 18–45 years, the average delay is 6.7 years (Nnoaham et al., 2011). A study conducted in an African country (Ethiopia) showed that women in the age group 40-44 had the highest occurrence of endometriosis (Eisenberg et al, 2018). This can be observed in figure 1 below.

Figure 1: Prevalence of endometriosis among various age groups (Eisenberg et al., 2018).

Several lesion types have been described which includes: 

-Superficial endometriosis found mainly on the pelvic peritoneum

-Cystic ovarian endometriosis (endometrioma) found in the ovaries

-Deep endometriosis found in the recto-vaginal septum, bladder, and bowel

-In rare cases, endometriosis has also been found outside the pelvis (Zondervan et al., 2020).

Causes of endometriosis

Endometriosis is a complex disease that affects women globally from the onset of their first menstruation (menarche) through menopause. The exact cause of endometriosis is not known as several factors contribute to its development (Agarwal et al., 2019). Some of these factors include:

1, Retrograde menstruation: This occurs when menstrual blood containing endometrial cells flows back through the fallopian tubes and into the pelvic cavity at the time that blood is flowing out of the body through the cervix and vagina during periods. Retrograde menstruation can result in endometrial-like cells being deposited outside the uterus where they can implant and grow (Agarwal et al., 2019). 

2, Cellular metaplasia: This occurs when cells change from one form to another. Cells outside the uterus change into endometrial-like cells and start to grow.

3, Stem cells give rise to the disease, which then spreads through the body via blood and through the lymphatic vessels (Johnson and Hummelshoj, 2013).

Endometriosis is also known to be dependent on the hormone estrogen as it facilitates the growth, inflammation and pain associated with the disease. Some other factors that contribute to the growth of the endometrial tissues in the body relate to impaired immunity, genetics and also environmental contaminants (Wen et al., 2019).

Presentation of Endometriosis

Its presentation varies in women and patients exhibit some of the following symptoms:

1, Painful periods (dysmenorrhea). Pelvic pain and cramps may begin before, and extend several days into the menstrual period. A study conducted by Fawole et al in 2019, revealed that the majority of the women who had endometriosis always experienced painful periods (dysmenorrhea) as seen in figure 2 below.

2, Pain during and/or after sexual intercourse

3, Painful bowel movement and urination

4, Fatigue

5, Depression or anxiety

6, Abdominal bloating and nausea (Zondervan et al., 2020).

Figure 2: Association between dysmenorrhea and endometriosis (Fawole et al., 2019).

Endometriosis in some cases can be asymptomatic and may only be detected during evaluation for infertility. Infertility occurs due to the probable effects of endometriosis on the pelvic cavity, ovaries, fallopian tubes or uterus (Agarwal et al., 2019). In 2019, the study conducted by Fawole et al., showed that 87% of the women who participated presented with infertility as a symptom (Figure 3). There is little correlation between the extent of endometrial lesions and severity or duration of symptoms: some individuals with visibly large lesions have mild symptoms, and others with few lesions have severe symptoms (Agarwal et al., 2019). Symptoms often improve after menopause, but in some cases, painful symptoms can persist. Chronic pain may be due to pain centers in the brain becoming hyper-responsive over time (central sensitisation), which can occur at any point throughout the life course of endometriosis, including treated, insufficiently treated, and untreated endometriosis, and may persist even when endometriosis lesions are no longer visible. In some cases, endometriosis can be asymptomatic (Zondervan et al., 2020).

Figure 3: Associated symptoms of endometriosis amongst Nigerian women (Fawole et al., 2019)

Risk factors associated with endometriosis

There are several risk factors associated with the development of endometriosis in individuals, and they include:

1, Never giving birth: Women who have never had a child tend to have a higher risk for endometriosis than women who have given birth. This is because pregnancy stops the menstrual cycle for a period of time. This break in the menstrual cycle lowers the amount of estrogen a woman is exposed to (Carey et al., 2017).

2, Starting your period at an early age: Early age at menarche, often defined as ≤11 years old, might increase a woman’s exposure to menstruation during her reproductive lifetime and consequently increase the risk of endometriosis (Gaudineau et al., 2010).

3, Short menstrual cycles: Cycles less than 27 days could potentially increase the frequency and the risk of retrograde bleeding and finally increase the incidence of endometriosis (Ming et al., 2016).

4, Heavy menstrual periods that last longer than seven days: the function of estrogen is to thicken the uterus lining. If estrogen level is high, the endometrium will be thicker and can cause heavy bleeding which is a risk factor for developing endometriosis (Carey et al., 2017).

5, Low body mass index: Several epidemiological studies have shown that an adverse relationship exists between body mass index and the incidence of endometriosis (Shahbazi & Shahrabi-Farahani, 2016).

6, Genetics: Several studies revealed that genome-wide association scan (GWAS) was able to identify genomic regions associated with the increased risk of endometriosis (Jenny et al., 2017)

7, Any medical condition that prevents the passage of blood from the body during menstrual periods

8, Disorders of the reproductive tract (Carey et al., 2017).


On presentation of symptoms, diagnosis can be done in several ways, they include:

1, Pelvic examination: This is done to manually feel (palpate) the areas in the pelvis for abnormalities, such as cysts on the reproductive organs or scars behind the uterus. It is however impossible to feel small areas of endometriosis unless they’ve caused a cyst to form.

2, Ultrasound: This test uses high-frequency sound waves to create images of the inner body. To capture the images, a device called a transducer is either pressed against the abdomen or inserted into the vagina (transvaginal ultrasound). Both types of ultrasound may be done to get the best view of the reproductive organs. A standard ultrasound imaging test won’t definitively show that one has endometriosis, but it can identify cysts associated with endometriosis (endometriomas) (WHO, 2018).

3, Magnetic resonance imaging (MRI): An MRI is an exam that uses a magnetic field and radio waves to create detailed images of the organs and tissues within the body. This test gives the surgeon detailed information about the location and size of endometrial implants.

4, Laparoscopy: This is a procedure that allows the surgeon to view inside the abdomen (laparoscopy), while the patient is placed under general anesthesia, the surgeon makes a tiny incision near the navel and inserts a slender viewing instrument (laparoscope), looking for signs of endometrial tissue outside the uterus. This procedure can also provide information about the location, extent and size of the endometrial implants. The biopsy obtained from the procedure can be taken for further testing (WHO, 2018). 

Treatment of endometriosis

Treatment can be with medications and/or surgery depending on symptoms, lesions, desired outcome, and patient’s choice (Johnson et al., 2017). 

Contraceptive steroids, non-steroidal anti-inflammatory medications, and analgesics (painkillers) are common therapies. All must be carefully prescribed and monitored to avoid potentially problematic side effects. Medical treatments for endometriosis focus on either lowering estrogen or increasing progesterone in order to alter hormonal environments that promote endometriosis (Johnson et al., 2013). 

These medical therapies include the combined oral contraceptive pill, progestins, and  Gonadotropin-releasing hormone (GnRH) analogues (Nnoaham et al., 2011). However, none of these treatments eradicates the disease, they are associated with side effects, and endometriosis-related symptoms can sometimes -but not always- reappear after therapy discontinuation. The choice of treatment depends on effectiveness in the individual, adverse side effects, long-term safety, costs, and availability. Most current hormonal management are not advised for persons suffering from endometriosis who wish to get pregnant, since they affect ovulation (Carey et al, 2017).

Surgery can also be used to remove endometriosis lesions, adhesions, and scar tissue. However, success in reducing pain symptoms and increasing pregnancy rates often depend on the extent of the disease. In addition, lesions may reoccur even after successful eradication, and pelvic floor muscle abnormalities (e.g. tense pelvic muscles, growth on the pelvis) can contribute to chronic pelvic pain (Zondervan et al., 2020). 

Secondary changes of the pelvis, including the pelvic floor, and central sensitisation may benefit from physiotherapy and complementary treatments in some patients. Treatment options for infertility due to endometriosis include laparoscopic surgical removal of endometriosis, ovarian stimulation with intrauterine insemination (IUI), and in vitro fertilization (IVF), but success rates vary (Johnson and Hummelshoj, 2013). 

Conclusion and recommendations

In summary, endometriosis is a debilitating disease that impacts the quality of life of adult and adolescent patients. Diagnostic delays are common and may lead to a decline in reproductive potential and fertility. Awareness programs about endometriosis among health care providers, women, men, adolescents, teachers and wider communities should be conducted often and at intervals. Local, national and international information campaigns should also be carried out to educate the public and healthcare providers about normal and abnormal menstrual health and the symptoms associated.

Training sessions for all healthcare providers as well, to improve their competency and skills to screen, diagnose, manage, or refer patients with endometriosis. More research on this subject matter should be conducted in Nigeria as there is a dearth of information on it.


Agarwal SK, Chapron C, Giudice LC, et al. Clinical diagnosis of endometriosis: a call to action. Am J Obstet Gynecol 2019(4):354-64.

Armour, M., Sinclair, J., Ng, C.H.M. et al.2020. Endometriosis and chronic pelvic pain have similar impacts on women, but time to diagnosis is decreasing: an Australian survey. Sci Rep 10, 16253.

Carey ET, Till SR, As-Sanie S. Pharmacological management of chronic pelvic pain in women. Drugs 2017;77:285-301.

Carter JE. Combined hysteroscopic and laparoscopic findings in patients with chronic pelvic pain. J Am Assoc Gynecol Laparosc. 1994;2:43–7.

Eisenberg VH, Weil C, Chodick G, Shalev V. Epidemiology of endometriosis: a large population-based database study from a healthcare provider with 2 million members. BJOG. 2018 Jan;125(1):55-62. doi: 10.1111/1471-0528.14711. Epub 2017 Jun 14. PMID: 28444957.

Fawole, A. O., Bello, F.O.,Olayinka, O, A., Nkwocha, G.,  Nnoaham, K. E., Zondervan, K.,, Adesina, A., and Okunlola, M. 2019. Endometriosis and associated symptoms among Nigerian women. International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics. 130. 10.1016/j.ijgo.2015.02.030. 

Gaudineau A., Ehlinger V., Vayssiere C., Jouret B., Arnaud C., Godeau E. Factors associated with early menarche: results from the French Health Behavior in School-aged Children (HBSC) study. BMC Public Health. 2010;10:175.  

Jenny, F.N., Yadav, S., Dale, R. N, and Grant, W.M. 2017. Genetic risk factors for Endometriosis. Journal of endometriosis and pelvic pain disorders. 9(2); 69-76. 

Johnson NP, Hummelshoj L, World Endometriosis Society Montpellier Consortium. Consensus on current management of endometriosis. Hum Reprod 2013;28(6):1552-68.

Johnson NP, Hummelshoj L, Adamson GD, et al. World Endometriosis Society consensus on the classification of endometriosis. Hum Reprod 2017;32(2):315-24.

Nisolle M, Donnez J. Peritoneal endometriosis, ovarian endometriosis, and adenomyotic nodules of the rectovaginal septum are three different entities. Fertil Steril. 1997;68(4):585–96.

Nnoaham K, Hummelshoj L, Webster P, et al. Impact of endometriosis on quality of life and work productivity: a multicenter study across ten countries. Fertil Steril 2011;96(2):366-73.e8. 

Shahbazi S, Shahrabi-Farahani M. 2016. Evaluation of the correlation between body mass index and endometriosis among Iranian fertile women. Gynecol Endocrinol.  32(2):157-60.

Wei, M., Cheng, Y., Bu, H., Zhao, Y., & Zhao, W. (2016). Length of Menstrual Cycle and Risk of Endometriosis: A Meta-Analysis of 11 Case-Control Studies. Medicine, 95(9), e2922. 

Wen X, Xiong Y, Qu X, et al. The risk of endometriosis after exposure to endocrine-disrupting chemicals: a meta-analysis of 30 epidemiology studies. Gynecol Endocrinol 2019;(35):645-50. 

World Health Organization (WHO). International Classification of Diseases, 11th Revision (ICD-11) Geneva: WHO 2018.

Zondervan KT, Becker CM, Missmer SA. Endometriosis. N Engl J Med 2020; 382:1244-56.