What's the Difference Between Adenomyosis and Endometriosis?

Both of the conditions can cause pelvic pain, but there are some key differences.

When a woman experiences painful periods, heavy bleeding, and chronic pain in the pelvic region, this constellation of symptoms could suggest endometriosis, a condition in which endometrial tissue spreads and implants beyond the uterus. During every menstrual period, this misplaced endometrial tissue can shed blood into the pelvic region and beyond, causing cysts, scar tissue, and adhesions to form over time.

But if the endometrial tissue burrows deep into the muscle of the uterus, and not outside the uterus, the diagnosis is actually adenomyosis, a condition that is related to endometriosis but has a few key differences.

In endometriosis, the endometrial tissue escapes from the uterus and might implant on the surface of the bladder, bowels, or other organs throughout the body. In adenomyosis, the endometrial tissue gets pushed into the myometrium muscle of the uterus, which is located between the inner and outer layers of the uterus organ. Once embedded in the muscle, this endometrial tissue sheds when the rest of the endometrium sheds during a period, which causes extra bleeding, pain, and cramping.

Adenomyosis vs. endometriosis symptoms

Both diseases can cause pain, Sanjay Agarwal, MD, director for the Center for Endometriosis Research and Treatment at the University of California, San Diego, tells Health. But women with adenomyosis generally tend to have pain related to their periods, while women with endometriosis might also feel pain with bowel movements and at other times in the cycle.

“With adenomyosis, the main impact on quality of life is a painful period,” Dr. Agarwal says. “Perhaps this is because endometriosis goes further afield.”

These two conditions don’t cause symptoms for everyone, however. It’s estimated that about one-third of women with adenomyosis experience no symptoms at all. And when it comes to asymptomatic endometriosis, it’s estimated that as many as 43% of women who end up undergoing sterilization for other reasons also show signs of mild endometriosis and were completely unaware of it.

Diagnosing adenomyosis vs. endometriosis

While more doctors are beginning to treat endometriosis based on symptoms like pelvic pain and painful periods, the most definitive diagnosis is made during a surgery called a laparoscopy, which is when doctors insert a thin tube with a light and camera into a small incision in the abdomen. With the tube, they can see endometrial lesions, cysts, and adhesions that make up endometriosis.

Diagnosing adenomyosis is much less invasive. Magnetic resonance imaging can help doctors see whether the myometrium is thicker than normal—one sign of the condition. MRIs and transvaginal ultrasounds can also help doctors identify cysts in the walls of the uterus, as well as myometrium with an abnormal texture. If the growths are limited to just a few cysts, the adenomyosis is classified as focal, while abnormal myometrium throughout the uterus is called diffuse adenomyosis.

Infertility in adenomyosis and endometriosis

Both conditions can also raise the risk for impaired fertility, or the inability to either conceive or carry a pregnancy to term.

When it comes to adenomyosis specifically, embryos can struggle to implant in the enlarged and “hard” uterus. Pregnancy losses are also more common. One study showed that women with adenomyosis undergoing in vitro fertilization had double the rate of miscarriages compared to women with both adenomyosis and endometriosis.

Adenomyosis also puts women and their babies at a higher risk of preterm birth and the premature rupture of the amniotic sac, as well as intrauterine growth restriction, pregnancy-related hypertension, and uterine infection.

If IVF doesn’t work, doctors might suggest a drug protocol called a gonadotropin-releasing hormone agonist, which suppresses the production of reproductive hormones like progesterone and estrogen in order to reduce the size of the uterine growths. Doctors may also attempt a surgery to remove the growths, known as adenomyomas, and reconstruct the uterus. These two alternative treatments have been shown to increase the chances of spontaneous pregnancy among women with adenomyosis, while the drug protocol may also help make IVF more successful.

However, depending on the size and spread of the condition, women with extensive adenomyosis might end up needing a surrogate to carry their pregnancy, Dr. Agarwal says.

Adenomyosis vs. endometriosis treatment

Treatment options for both conditions are similar and escalate in intensity from birth control pills to suppress the release of reproductive hormones to surgery to remove endometrial cysts, scar tissue or implants, adenomyomas, or even the entire uterus.

In between those two ends of the spectrum, women can try other hormonal medications to drive down the production of estrogen, a hormone that makes both adenomyosis and endometriosis worse. These drugs, delivered through injections, hormonal IUDs, or pills, have been shown to reduce menstrual cramping, pain during sex, and chronic pelvic pain in both conditions.

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