What are the causes of PMB?

In general, post-menopausal bleeding comes from somewhere within the uterine cavity. However, blood can also come from the vulva, vagina, cervix and even the fallopian tube. Some of the causes of postmenopausal bleeding that originate in the uterus include:

Endometrial polyps – Polyps are little outpouchings of uterine lining tissue.  The vast majority of polyps are benign but they are a common source of PMB.  Polyps, if found, need to be removed and analyzed.  A small percentage of them contain cancers.  Additionally, unless they are removed in their entirety (down to the muscle of the uterus) there’s a high likelihood of regrowth and they continue to produce annoying bleeding.

Endometrial Polyps Diagram

The risk factors for polyps include hormone replacement therapy, the use of tamoxifen as well as obesity.

Multiple Leiomyomas Diagram

Fibroids (Leiomyomas) – Fibroids are much more commonly associated with pre-menopausal bleeding issues than PMB.  However, they occasionally cause both.  The vast majority of these fibroids are benign.  Fibroids that cause PMB are generally of the submucous variety.

Endometrial hyperplasia – This is a condition in which the endometrium (uterine lining) becomes too thick.  Although the condition is benign, some cases are pre-cancerous and can—one day—develop into a uterine cancer.  The risk factors for endometrial hyperplasia include the use of estrogen-like medications, use of high dose estrogens without accompanying progestins, a history of polycystic ovarian syndrome and obesity.

Endometrial Cancer – The incidence of endometrial cancer in women with postmenopausal bleeding is approximately 5%.  The risk increases with age, obesity, diabetes, hypertension or a previous history of breast cancer.  Other risk factors include a prior history of certain types of endometrial hyperplasia, unopposed estrogen use and tamoxifen therapy for breast cancer.

Atrophy – Over a period of years following menopause there is a loss of moisture and fluid normally found within the uterine cavity.  It is not uncommon for the uterine cavity to develop fine cracks.  Think of what might happen to your gums or the inside of your cheeks if you didn’t make saliva—they’d dry out, crack and bleed.  The same can happen inside your uterine cavity.  Bleeding from atrophy is generally minimal, occurs in women many years postmenopausal (at least 10) and typically occurs in the absence of hormone replacement therapy.

Anticoagulant use – The use of Coumadin (warfarin) carries a risk of postmenopausal bleeding.

Herbal supplements – Certain over-the-counter plant-based estrogens are known to be associated with postmenopausal bleeding.

Hormone replacement therapy – Estrogen in the form of patches, vaginal creams, pills or capsules can all cause PMB.