What is the difference between adenomyosis and endometriosis?
TLDR: This piece examines two conditions that both involve the endometrial tissue of the uterus and have overlapping symptoms; endometriosis and adenomyosis. This article covers disease descriptions, what happens during menses, symptoms, diagnosis, management, and prevalence.
Both adenomyosis and endometriosis are conditions that involve the tissue which lines the uterine wall (i.e., the endometrium) (1, 2). The biological cause of both these conditions is so far unknown. Both conditions are associated with infertility and have some overlapping symptoms.
Adenomyosis and endometriosis can co-occur (3, 4). In other words, one person can have both adenomyosis and endometriosis.
This piece will examine the following for both conditions:
Description of disease
What happens during menses
Note: Uterine lining, endometrium, and endometrial lining are equivalent terms. They all refer to the layer of tissue that lines the inner walls of the uterus.
This piece reports on adenomyosis and endometriosis research as it exists today. However, we must recognize that both adenomyosis and endometriosis are under-researched and underdiagnosed, which limits our current understanding of these conditions. I do not want this article to be viewed as objective truth or inadvertently perpetuate a non-comprehensive view of these complex conditions. Here are some considerations:
a. Both these conditions require invasive procedures for diagnosis and treatment. This is reflective of insufficient research to develop new diagnostic and treatment methods. This is not reflective of the “mystery” or “enigma” of the “female body.”
b. Just because both adenomyosis and endometriosis are rarely diagnosed before puberty or after menopause, this does not mean they cannot present at these times. We must not write off symptoms that indicate adenomyosis and/or endometriosis as not being either of these conditions simply because of age or life stage at the time of onset.
c. Both conditions are reported to lessen or go away with menopause. This is because estrogen and progesterone hormone levels do not spike and fluctuate after menopause as dramatically as they do during the menstrual cycle. However, estrogen and progesterone are still produced in the body even after menopause. This means that, for some people, adenomyosis and endometriosis may continue even after menopause. This should not be disregarded and symptoms present after menopause should not be invalidated.
d. While adenomyosis has mostly been diagnosed in older women, this does not mean that younger women cannot have this disease. Adenomyosis is commonly diagnosed after hysterectomy surgery to remove the uterus. Since this surgery means you cannot get pregnant, young women may be less likely to undergo this procedure. This may partially explain why younger women are not diagnosed with adenomyosis. This prevalence data may change as more advanced diagnostic techniques are developed.
e. Endometriosis is less frequently diagnosed in Black women. This does not mean that Black women are less likely to have endometriosis. In fact, this discrepancy is likely due to the historical understanding of endometriosis as a disease of “affluent, high-achieving women with private health insurance” (15). Historically, this has always been white women. Compounded with racist ideas and practices which undermine pain in Black people, it is more likely that endometriosis is misdiagnosed in Black women. There is a lack of race-based data in the prevalence/diagnosis of adenomyosis.
f. Finally, the two studies cited under the prevalence section for adenomyosis report very different findings. One reports an incidence of 1% (Naftalin et al.), and the other reports an incidence of 20% (Yu et al.). There are numerous explanations for this discrepancy. First of all, Naftalin et al. was conducted through a hospital health insurance system, whereas Yu et al. was conducted at a gynaecology clinic. People who are coming to a gynaecology clinic are more likely to have gynaecological symptoms (such as those associated with adenomyosis) than those going to the hospital for various conditions. Secondly, Naftalin et al. was a retrospective study where the researchers looked for diagnoses of adenomyosis in patient charts. On the other hand, Yu et al. was a prospective study where women presented to the clinic with symptoms and were assessed for adenomyosis by ultrasound. This means that the two studies have very different ways of identifying adenomyosis, which could partially explain why they report different incidence values. Differences in the study population, number of participants, method of diagnosis, and other factors have led to a prevalence of adenomyosis anywhere from 5-70% across studies (16).
I hope the considerations above have shown how clinical practice and clinical data can interact. For example, if a healthcare provider believes that endometriosis cannot continue/ occur after menopause, then that provider will be less likely to think that endometriosis-like symptoms present after menopause are in fact, endometriosis. This can lead to delays in diagnosis and treatment. If a researcher at that healthcare provider’s clinic then studies how many people have endometriosis after menopause, they may report an artificially low number because the provider isn’t diagnosing the condition as such. This research then reinforces to the healthcare provider that endometriosis cannot be present after menopause. The purpose of this simplistic example and the other considerations above is not to invalidate the current research but to recognize potential limitations in data that can impact practice and healthcare outcomes for patients.
All sources except ‘14’ do not specify gender identity. Historical representation leads us to believe only cisgender people were included.
Mayo Clinic. Adenomyosis. 2020 Jun 18. Available from: https://www.mayoclinic.org/diseases-conditions/adenomyosis/symptoms-causes/syc-20369138. [Accessed 2021 Mar 11].
Mayo Clinic. Endometriosis. 2019 Oct 16. Available from: https://www.mayoclinic.org/diseases-conditions/endometriosis/symptoms-causes/syc-20354656. [Accessed 2021 Mar 11].
Yu O, Schulze-Rath R, Grafton J, Hansen K, Scholes D, & Reed SD. Adenomyosis incidence, prevalence and treatment: United States population-based study 2006–2015. American Journal of Obstetrics & Gynecology. 2020; 223(1):P94.E1-94.E10. Available from: https://doi.org/10.1016/j.ajog.2020.01.016.
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