- Adenomyosis is often called the "evil sister" of endometriosis.
- Adenomyosis is where endometrial tissue grows in the outer muscular walls of the uterus.
Endometriosis and adenomyosis are similar conditions in which abnormal tissue grows somewhere it shouldn't.
Symptoms of both endometriosis and adenomyosis can vary from person to person, but typically include pelvic pain, heavy or painful periods, and infertility.
Though adenomyosis is often referred to as the "evil sister" of endometriosis, these two disorders are different but can often occur simultaneously. In fact, up to 50% of people with adenomyosis also have endometriosis.
Keep reading to learn the differences between endometriosis and adenomyosis, including common symptoms and how to get a proper diagnosis.
What is adenomyosis?
Adenomyosis is a chronic condition in which endometrial tissue (the tissue that lines the uterus) grows into the myometrium, the outer muscular walls of the uterus, damaging the uterine wall.
Over time, this tissue buildup can cause the uterus to enlarge, leading to chronic pain, abnormal uterine bleeding, and painful periods.
"Endometriosis and adenomyosis are similar in that they are both caused by endometrial tissue that is found outside the uterine cavity where it should be," says Christine Peter, RNC-OB, C-EFM. "With adenomyosis, the endometrial tissue invades the wall of the uterus and is found in the muscle layers of the uterus itself rather than just the lining."
What is endometriosis?
Endometriosis is a chronic, inflammatory condition in which endometrial-like tissue grows outside the uterus.
Endometriosis is commonly found on the ovaries, fallopian tubes, and pelvic lining, but it can also grow in other places, including the bladder, bowel, and lungs.
"The difference for all practical purposes is, when the tissue responsible for menstruation is found anywhere outside the uterus or outside of the endometrial cavity, this is called endometriosis," says Dr. Tamer Seckin, laparoscopic surgeon and co-founder of the Endometriosis Foundation. "If the bed of the endometrium is situated within the uterus, but beyond the cavity inside the muscle wall, it's called adenomyosis."
Adenomyosis symptoms
Nearly one-third of people with adenomyosis are asymptomatic or have no symptoms. For others, common symptoms of adenomyosis include:
- Cramping and heavy menstrual bleeding
- Painful bowel movements
- Dyspareunia (painful intercourse)
- Burning during urination
- Blood in the urine
- Swelling of the abdomen
- Leg or bowel pain during menstruation
Endometriosis symptoms
Endometriosis has a few telltale signs, including heavy and painful periods, chronic pelvic pain, and pain with sex.
Other symptoms of endometriosis include:
- Abdominal pain and bloating
- Painful bowel movements
- Bladder dysfunction
- Chronic fatigue
- Infertility
- Mood and personality changes (stress, depression, anxiety)
- Neuropathy (numbness, weakness, or pain in the nerves)
"Symptoms can be similar for both conditions and usually include pelvic pain, painful, heavy periods, and painful intercourse," says Peters. "With endometriosis, patients are more likely to experience painful bowel movements or pain when urinating, more generalized abdominal pain rather than sharp pelvic pain, and leg pain, especially during menstruation."
How is adenomyosis diagnosed?
Adenomyosis mimics the symptoms associated with other conditions, such as fibroid tumors and endometrial polyps, and it can be difficult to get a definitive diagnosis.
According to the Seckin Endometriosis Center, pathology (following hysterectomy) is the gold standard for diagnosing adenomyosis. However, modern imaging techniques such as magnetic resonance imaging (MRI) have made it easier for specialists to view the myometrium and determine whether or not a person has adenomyosis.
A pelvic ultrasound can also show cysts within the uterine muscle, providing enough evidence for an experienced doctor to find and identify suspected adenomyosis.
"Because the only positive diagnosis for adenomyosis requires such an invasive and final procedure, doctors will often make a clinical diagnosis based on symptoms and exam findings (enlarged uterus)," says Peters. "Unfortunately, other conditions, such as uterine fibroids, can cause similar symptoms, so it often goes misdiagnosed."
Insider's takeaway
Endometriosis and adenomyosis can cause similar symptoms, including pelvic pain, painful periods, and heavy bleeding. However, as similar as they are, endometriosis and adenomyosis are quite different.
The main difference is the location where the disease grows: Endometriosis grows outside of the uterus, whereas adenomyosis grows inside the uterine wall.
There is no definitive way to diagnose one or the other without surgery.