Endometriosis versus Adenomyosis: Comparing the Symptoms, Diagnosis and Treatment Options

Endometriosis affects about 1 in 10 females worldwide, with most diagnoses often being made in people in their 30s and 40s. [1]

Adenomyosis, on the other hand, is less common but still affects an estimated 2% to 5% of adolescents and is characterized by severely painful periods. [2] 

It is also possible to have both endometriosis and adenomyosis at the same time, and studies suggest that adenomyosis is more common in women who already have endometriosis. This overlap can make symptoms worse and harder to treat.

Traditionally, diagnosis has relied on laparoscopic surgery, but ongoing research is paving the way for less invasive methods. Likewise, treatment approaches are expanding beyond traditional pain relief and surgery, now including hormonal therapies and lifestyle strategies. These developments are helping patients receive faster diagnoses and more personalized care.

Endometriosis versus Adenomyosis

Figure 1. An illustration comparing endometriosis and adenomyosis side by side. On the left, the image shows endometrial-like tissue growing outside the uterus on the ovaries, fallopian tubes, and pelvic lining. On the right, endometrial tissue is growing within the uterine muscle wall, causing the uterus to appear enlarged and thickened. (Image source: Northside Gynaecology)

When the tissue that forms the inner lining of the uterus, called endometrium, grows outside the uterus, it leads to a condition called endometriosis.

Endometrial tissue growths are often found on the ovaries, fallopian tubes, the lining of the pelvis, and sometimes the bladder and bowel. Rarely, it also grows on the peritoneum, vagina, rectum, intestines, the diaphragm, and the lungs.

Adenomyosis, on the other hand, refers to endometrial tissue growing into the muscular wall of the uterus, called the myometrium.

The Symptoms

Because the symptoms of endometriosis and adenomyosis overlap so much, it’s not always easy to tell which condition is responsible.

Common Symptoms

• Painful menstrual cramps (dysmenorrhea)

• Pelvic pain before and during periods

• Chronic lower back or abdominal pain

• Pain during sex (dyspareunia)

• Heavy menstrual bleeding (menorrhagia)

• Bloating or a sensation of fullness

• Nausea and vomiting

• Fatigue (due to pain or anemia from heavy bleeding)

Symptoms More Often Seen In Endometriosis

Just like the normal endometrial lining inside the uterus, the tissue growing outside the uterus also responds to monthly hormonal changes. This means it gets thicker and can bleed during your period, but since the tissue doesn’t leave the body, it causes inflammation and scarring in the surrounding tissues. This leads to symptoms like:

• Pain while passing urine or stool during periods

• Digestive issues like diarrhea, constipation, or nausea around your period

• In some cases, spotting or bleeding between periods

• Endo belly – Severe bloating that sometimes resembles a pregnant belly. It can last for hours, to days, or even weeks.

Symptoms More Often Seen In Adenomyosis

With adenomyosis, since the tissue is growing inside the uterus, the uterus thickens and becomes enlarged, which doesn’t usually happen with endometriosis. This causes specific symptoms like:

• A feeling of pressure in the lower abdomen

• Intense cramping that gets worse over time (dysmenorrhea)

• Heavier periods that may last longer than usual

What Causes Endometriosis And Adenomyosis?

Doctors and researchers have studied these conditions for decades, but the exact causes of endometriosis and adenomyosis are still not fully understood. What we do know is that both are influenced by a mix of hormonal, genetic, and immune system factors.

Possible Causes of Endometriosis

1. Retrograde menstruation – During periods, some menstrual blood flows backward through the fallopian tubes into the pelvic cavity instead of leaving the body. This could allow endometrial-like cells to stick to and grow on the pelvic wall or surface of pelvic organs. [3]

2. Cell transformation – Cells in the abdominal/pelvic area may transform into endometrial-like cells under certain hormonal or immune triggers. [3]

3. Immune system changes – In some women, the immune system may not effectively clear away misplaced endometrial cells, allowing them to grow. [3]

4. Spread through blood or lymph – In rare cases, cells may travel to distant parts of the body through blood vessels or the lymphatic system. [3]

Possible Causes of Adenomyosis

1. Injury to the uterine lining – Events like childbirth, cesarean sections, or uterine surgeries may create openings in the boundary between the uterine lining and muscle, allowing endometrial cells to invade. [4]

2. Developmental origins – Some women may be born with misplaced endometrial cells within the uterine muscle, which only cause symptoms later in life. [4]

3. Inflammation related to childbirth – Chronic inflammation in the uterus during the postpartum period may lead to a break in the normal boundary of cells lining the uterus, and make it easier for cells to invade the muscular wall. [4]

4. Stem cells – Some researchers believe that bone marrow stem cells, which can develop into different cell types, may invade the uterine muscular layer and cause adenomyosis. [4]

Who Is At Risk Of Endometriosis And Adenomyosis?

Your chances of developing endometriosis go up if:

• Your mother, sister, or daughter has endometriosis.

• You started menstruation before age 11.

• Your periods are closer together (less than 27 days apart).

• You have heavy menstrual flow for more than 7 days.

• You’ve never given birth.

Some studies also suggest that white women are more likely to be diagnosed with endometriosis than Black and Hispanic women. [5]

Your risk of adenomyosis goes up if:

• You are in your 40s or older.

• You have given birth at least once.

• You started menstruation before the age of 10.

• You underwent uterine surgery, such as a cesarean section or fibroid removal, or dilation or curettage.

• Your menstrual cycles last 24 days or less.

• You have endometriosis.

How Are Endometriosis And Adenomyosis Diagnosed?

Figure 2. The illustration shows a doctor performing laparoscopic surgery. The patient lies on an operating table under anesthesia, with the abdomen gently inflated to create working space. The surgeon is inserting a thin laparoscope through a small incision near the navel. (Image source: Statesboro Women's Health Specialists)

Healthcare providers begin with a pelvic exam, transvaginal ultrasound, and MRI if they suspect either endometriosis or adenomyosis. However, to confirm the diagnosis, a laparoscopy is necessary.

Laparoscopy is a minimally invasive surgery where a small camera called the laparoscope is inserted into the abdomen through a tiny cut made near the belly button. It allows the surgeon to see directly inside your pelvis and identify endometrial tissue. Small pieces of the tissue are then collected and sent for laboratory testing (biopsy) to confirm the diagnosis.

While it is considered the gold standard for diagnosing endometriosis, laparoscopy requires anesthesia and carries surgical risks like bleeding and infection. For this reason, less than 20% of women opt for it.

When it comes to adenomyosis, a biopsy won’t help confirm the diagnosis. The only way is to wait until hysterectomy (surgical removal of the uterus), and then send the uterine tissue for a lab test.

Advances In The Diagnosis Of Endometriosis And Adenomyosis

In recent years, non-invasive diagnostic tools for endometriosis have been intensely studied. One promising approach examines microRNAs (miRNAs), which are molecules that regulate gene expression. [6]

Some types of miRNAs appear to be unique in women with endometriosis. A saliva-based test has been developed in France that claims very high accuracy (up to 97% sensitivity and 100% specificity in an internal study of 200 women). [6]

Hopefully, this sali test will be fully validated in large, diverse populations and soon incorporated into clinical practice guidelines.

Other exciting innovations include ultrasound shear wave elastography (US-SWE) and magnetic resonance elastography (MRE), which measure tissue stiffness to detect endometriotic and adenomyotic lesions more objectively than traditional imaging. [7]

Positron emission tomography (PET) combined with computerized tomography (CT) is also showing promise by using special tracers to highlight areas of inflammation or abnormal cell activity linked to the disease. [7]

Together, these tools could reduce the need for invasive laparoscopy, enabling earlier detection, quicker treatment, and better outcomes for patients.

How Are Endometriosis And Adenomyosis Treated?

Treatment for both conditions depends on your symptoms, how much they affect your daily life, whether you want to get pregnant, and whether you have one or both conditions. With most treatment plans, the goal is to relieve pain, control bleeding, and protect fertility.

Medications For Symptom Control

• Combined Oral Contraceptives (COCs) – These are hormonal medications containing estrogen and synthetic progesterones used to regulate or stop periods and reduce associated pain and bleeding. [First-line therapy]

• Progestin therapy – Can stop menstruation and thereby relieve symptoms. [Second-line therapy]

• GnRH agonists/antagonists – They temporarily lower estrogen levels, putting the body in a reversible menopause-like state to shrink lesions and reduce bleeding.

• Anti-inflammatory drugs – nonsteroidal anti-inflammatory drugs (NSAIDs) help reduce menstrual cramps and pelvic pain.

• Aromatase inhibitors – They lower estrogen levels in the body, and potentially reduce the size of endometrial tissue growth.

Surgical Options

• Conservative surgery – Laparoscopic removal (excision) or destruction (ablation) of the endometrial tissue to relieve pain and improve fertility while preserving reproductive organs.

• Adenomyomectomy – Surgery to remove adenomyotic tissue from your uterine muscle, usually for women wanting to preserve fertility. (Note: Adenomyotic tissue is the endometrial tissue that has grown into the myometrium, or the muscular wall of the uterus, forming small growths.)

• Hysterectomy – Surgery to remove your uterus. The only definitive cure for adenomyosis. It’s usually considered when symptoms are severe, fertility is no longer a goal, and other treatments haven’t worked.

New Therapeutic and Lifestyle Opportunities In Managing Endometriosis and Adenomyosis

While there’s no cure yet for endometriosis or adenomyosis, research is bringing fresh hope.

Researchers have discovered that endometriosis shares certain genetic risk factors with other health conditions like migraine, IBS (irritable bowel syndrome), depression, and even asthma. This has prompted exploration of existing drugs for new uses. For example, CGRP (calcitonin gene-related peptide) is a neuropeptide involved in pain signaling and inflammation. In people with endometriosis, higher levels of CGRP and nerve fibers that release it are often found around lesions. For this reason, researchers are now exploring CGRP pathway inhibitors (originally developed for migraine) as potential non-hormonal treatment to reduce pain and inflammation in endometriosis.  [7]

In addition, chronic inflammation is central to many conditions, and new therapies are aiming to block specific inflammatory signals, without the long-term side effects of common painkillers. mPGES-1 inhibitors (which lower prostaglandin E2 levels) and IL-8 blocking antibodies have already demonstrated their ability to shrink endometriotic lesions in early clinical trials. [6]

There is also growing evidence that certain diets can help ease symptoms. The Low FODMAP diet is one such diet that was reported to have helped more than half of women with both endometriosis and IBS. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These are types of carbohydrates that are poorly absorbed by the small intestine and can cause bloating and pain in sensitive individuals.

Going gluten-free has been linked to pain reduction in up to 75% of women, and natural supplements like curcumin (from turmeric) have been shown to cut NSAID use nearly in half. [7]

Some studies have also shown regular soy consumption to be linked to a reduced risk of endometriosis in pre-menopausal women. Soy contains natural plant compounds called isoflavones, which can mimic estrogen in the body but may have a balancing effect on hormone levels. This could potentially offer some protection against hormonally driven conditions like endometriosis. [8]

Artificial intelligence (AI) is now being used to scan huge genetic and drug databases to find promising new treatment targets. This could bring more precise, personalized therapies to clinical trials within the next five years. [7]

Some Helpful Advice…

If you experience severe menstrual cramps, chronic pelvic pain, or a noticeable “endo belly” (a swollen belly) near the time of your period, it's important not to dismiss these symptoms as normal. You should immediately speak with a gynecologist who can guide you through the appropriate tests and treatment options. Early evaluation and care can prevent progression and improve your overall quality of life.