Menstrual Disorders - Causes

Highlights	Risk Factors	Medications
Introduction	Complications	Surgery
Menstrual Disorders	Diagnosis	Resources
Causes	Treatment	References

Causes

Menstrual disorders can be triggered by a number of different factors, such as hormone imbalances, genetic factors, clotting disorders, and pelvic diseases.

Dysmenorrhea

Contraction-Causing Chemicals. Powerful chemicals known as prostaglandins and arachidonic acidcaninduce uterine muscle contractions. Prostaglandins also play a large role in the heavy bleeding that causes dysmenorrhea.
Abnormal Nervous System Response. Some women with primary dysmenorrhea may have autonomic nervous systems that are overly sensitive to menstrual cycle changes. The autonomic nervous system regulates heart rate andblood pressure, and it contains the pain receptors in nerve fibers in the uterus and pelvic area. As a result, women with autonomic nervous system abnormalities may have a more intense response to pain.
Abnormalities in the Arteries in the Uterus.Impaired blood flow through the arteries in the uterus may cause severe dysmenorrhea for some women.
Genetic Factors. Genetic factors may play an importantrole in over half of primary dysmenorrhea cases.
Endometriosis. Endometriosis is a chronic and often progressive disease that develops when the tissue that lines the uterus (endometrium) growsonto other areas, such as the ovaries, bowels, or bladder.[For more information, see In-Depth Report #74: Endometriosis].

Endometriosis is the condition in which the tissue that normally lines the uterus (endometrium) grows on other areas of the body causing pain and irregular bleeding.

Uterine Fibroids. Fibroids are noncancerous growths that grow on the walls of the uterus. They can cause heavy bleeding during menstruation and cramping pain. [For more information, see In-Depth Report #73: Uterine Fibroids.]
Other Causes. Pelvic inflammatory disease, ovarian cysts, and ectopic pregnancy. The intrauterine device (IUD) contraceptive can also cause dysmenorrhea.

Menorrhagia

Hormonal imbalances and uterine fibroids are the most common causes of menorrhagia. Other causes of menorrhagia include:

Dysfunctional Uterine Bleeding (DUB). DUBis a general term for abnormal bleeding. Itis usually caused by hormonal problems and is one of the primary causes of menorrhagia. DUB usually occurs either when girls begin to menstruate orwhen women approach menopause, but it can occur at any time in during a woman''s reproductive life. About 90% of DUB events occur when ovulation is not occurring (anovulatory DUB). In such cases, women do not properly develop and release a mature egg. When this happens, the corpus luteum does not form. As a result, estrogen is produced continuously, causing an overgrowth of the uterus lining. The period is delayed in such cases, and when it occurs menstruation can be very heavy and prolonged. The other 10% of DUB cases occur in women who are ovulating (ovulatory DUB), but progesterone secretion is prolonged because estrogen levels are low. This causes irregular shedding of the uterine lining and break-through bleeding.
Von Willebrand Disease and Other Bleeding Disorders. Bleeding disorders that stop blood from clotting can cause heavy menstrual bleeding. Most of these disorders have a genetic basis. Von Willebrand disease is the most common of these bleeding disorders and may be underdiagnosed in many women with unexplained menorrhagia.
Abnormal Blood Vessel Growth. Every month, blood vessels regrow in the uterus to replace the blood-rich uterine lining lost during menstruation. Abnormalities in this growth process (called arteriogenesis or angiogenesis) may occur in some women with menorrhagia.
Abnormalities in the Uterus. Structural problems or other abnormalities in the uterus may cause bleeding. They include uterine polyps (small benign growths in the uterus), uterine fibroids, endometriosis, adenomyosis, and miscarriage. Infections or inflammation in the vagina or pelvic area can also cause heavy bleeding.
Medications. Certain drugs, including anticoagulants and anti-inflammatory medications, can cause heavy bleeding.
Cancer. Uterine, ovarian, and cervical cancer can cause excessive bleeding but these are rare causes.
Other Medical Conditions. Systemic lupus erythematosus, diabetes, pelvic inflammatory disorder, and thyroid disorders can cause heavy bleeding.