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What Is Polycystic Ovary Syndrome?

Polycystic ovary syndrome (PCOS) causes harmless cysts in the ovaries and also causes other symptoms. PCOS is caused by certain hormones being out of balance. The word “syndrome” means a group of symptoms. Women with PCOS may have no periods, irregular periods, or very long periods.

Front view of uterus, fallopian tubes, and ovaries. Half of uterus in cross section to show inside. Closeup of normal ovary showing fluid in enlarged follicle. Closeup of polycystic ovary showing many fluid-filled cysts.

Your Ovaries

A woman’s ovaries are where her eggs are stored. Each egg is in a capsule called a follicle. Each month, one follicle grows to produce a mature egg. This egg is released (ovulation) and the follicle dissolves.

Hormones out of Balance

With polycystic ovary syndrome (PCOS), the chemicals (hormones) that control ovulation are out of balance. These include estrogen and androgen (a male hormone). As a result, ovulation may not occur. Instead, the follicle stays enlarged. This is a cyst (fluid-filled sac). Over time, the ovaries fill with many cysts. This is why they are called “poly” (many) “cystic” ovaries. In some women, the ovaries also make too many male hormones.

PCOS Symptoms

Women with PCOS may also have one or more of these symptoms:

  • Trouble getting pregnant (fertility problems)

  • Weight gain

  • Acne

  • Hair growth on the face and other parts of the body

If it is not treated, PCOS may also increase a woman’s risk for cancer of the uterine lining.

Online Medical Reviewer: Bowers, Nancy, RN, BSN, MPH
Online Medical Reviewer: Freeborn, Donna, PhD, CNM, FNP
Last Review Date: 11/19/2012
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