The cause of adenomyosis isn't known. Expert theories about a possible cause include:

  • Invasive tissue growth. Some experts believe that adenomyosis results from the direct invasion of endometrial cells from the surface of the uterus into the muscle that forms the uterine walls. Uterine incisions made during an operation such as a cesarean section (C-section) may promote the direct invasion of the endometrial cells into the wall of the uterus.
  • Developmental origins. Other experts speculate that adenomyosis originates within the uterine muscle from endometrial tissue deposited there when the uterus first formed in the female fetus.
  • Uterine inflammation related to childbirth. Another theory suggests a link between adenomyosis and childbirth. An inflammation of the uterine lining during the postpartum period might cause a break in the normal boundary of cells that line the uterus.
  • Stem cell origins. A recent theory proposes that bone marrow stem cells may invade the uterine muscle, causing adenomyosis.

Regardless of how adenomyosis develops, its growth depends on the circulating estrogen in a woman's body. When estrogen production decreases at menopause, adenomyosis eventually goes away.

Jun. 07, 2012