What are the anatomic causes of menorrhagia?

Updated: Dec 20, 2018
  • Author: Julia A Shaw, MD, MBA, FACOG; Chief Editor: Michel E Rivlin, MD  more...
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Anatomic etiologies for menorrhagia include uterine fibroids, endometrial polyps, endometrial hyperplasia, and pregnancy. Note the following:

  • Fibroids and polyps are benign structures that distort the uterine wall and/or endometrium. Either may be located within the uterine lining, but fibroids may occur almost anywhere on the uterus.

  • The mechanism by which endometrial polyps or fibroids cause menorrhagia is not well understood. The blood supply to the fibroid or polyp is different compared to the surrounding endometrium and is thought to function independently. This blood supply is greater than the endometrial supply and may have impeded venous return, causing pooling in the areas of the fibroid. Heavy pooling is thought to weaken the endometrium in that area, and break-through bleeding ensues.

  • Fibroids located within the uterine wall may inhibit muscle contracture, thereby preventing normal uterine attempts at hemostasis. This also is why intramural fibroids may cause a significant amount of pain and cramping. Fibroids may enlarge to the point that they outgrow their blood supply and undergo necrosis. This also causes a great deal of pain for patients.

  • Endometrial hyperplasia usually results from unopposed estrogen production, regardless of the etiology. Endometrial hyperplasia can lead to endometrial cancer in 1-2% of patients with anovulatory bleeding, but it is a diagnosis of exclusion in postmenopausal bleeding (average age at menopause is 51 y). If a woman takes unopposed estrogen (without progesterone), her relative risk of endometrial cancer is 2.8 compared to nonusers. [21]

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