What is adenomyosis?

Adenomyosis (add-en-o-my-OH-sis) is a condition of the female reproductive system. It causes the uterus to thicken and enlarge.

Endometrial tissue lines the inside of the uterine wall (endometrium). Adenomyosis occurs when this tissue grows into the myometrium, the outer muscular walls of the uterus. This extra tissue can cause the uterus to double or triple in size and lead to abnormal uterine bleeding and painful periods.

What is the difference between adenomyosis and endometriosis?

Adenomyosis and endometriosis are disorders that involve endometrial tissue. Both conditions can be painful. Adenomyosis is more likely to cause heavy menstrual bleeding. The difference between these conditions is where the endometrial tissue grows.

  • Adenomyosis: Endometrial tissue grows into the muscle of the uterus.
  • Endometriosis: Endometrial tissue grows outside the uterus and may involve the ovaries, fallopian tubes, pelvic side walls, or bowel.

How common is adenomyosis?

Many women aren’t aware they have adenomyosis because the condition doesn’t always cause symptoms. The condition may affect 20% to 65% of females.

Who might get adenomyosis?

Adenomyosis has been found in adolescents, but typically occurs in females between the ages of 35 and 50 who have:

What causes adenomyosis?

Experts don’t know why some people develop adenomyosis. The condition is more common in women who have had children.

What are the symptoms of adenomyosis?

Many people with adenomyosis don’t have symptoms. Some people experience:

Last reviewed by a Cleveland Clinic medical professional on 08/18/2020.


  • Merck Manual. Adenomyosis. Accessed 8/21/2020.
  • The American College of Obstetricians and Gynecologists (ACOG). Heavy Menstrual Bleeding. Accessed 8/21/2020.
  • Dougherty MP, DeCherney AH. Dougherty M.P., & DeCherney A.H. Dougherty, Michael P., and Alan H. DeCherney.Benign Disorders of the Uterine Corpus. In: DeCherney AH, Nathan L, Laufer N, Roman AS. DeCherney A.H., & Nathan L, & Laufer N, & Roman A.S.(Eds.),Eds. Alan H. DeCherney, et al.eds. CURRENT Diagnosis & Treatment: Obstetrics & Gynecology, 12e. McGraw-Hill; Accessed 8/21/2020.

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