Adenomyosis (ad-uh-no-my-O-sis) occurs when the tissue that normally lines the uterus (endometrial tissue) grows into the muscular wall of the uterus. The displaced tissue continues to act normally — thickening, breaking down and bleeding — during each menstrual cycle. An enlarged uterus and painful, heavy periods can result.

Doctors aren’t sure what causes adenomyosis, but the disease usually resolves after menopause. For women who have severe discomfort from adenomyosis, hormonal treatments can help. Removal of the uterus (hysterectomy) cures adenomyosis may suspect adenomyosis based on:

  • Signs and symptoms
  • A pelvic exam that reveals an enlarged, tender uterus
  • Ultrasound imaging of the uterus
  • Magnetic resonance imaging (MRI) of the uterus

In some instances, your doctor might collect a sample of uterine tissue for testing (endometrial biopsy) to make sure you don’t have a more serious condition. But an endometrial biopsy won’t help your doctor confirm a diagnosis of adenomyosis.

Pelvic imaging such as ultrasound and MRI can detect signs of adenomyosis, but the only way to confirm it is to examine the uterus after hysterectomy.

With adenomyosis, the same tissue that lines the uterus (endometrial tissue) is present within and grows into the muscular walls of your uterus.