For ovulation to occur, a series of synchronized messages between the pituitary gland (which is located at the base of the brain) and a healthy ovary must take place. Approximately 25% of all women with infertility have an abnormality with ovulation. Irregular cycles (<21 days or >35 days), abnormal bleeding, or a complete cessation in menses suggest an ovulatory disorder.
Ovulatory disturbances can be caused by any process which may disrupt the messages between the brain and the ovary, which can include polycystic ovary syndrome (PCOS), medications, rapid weight gain or loss, thyroid dysfunction, elevations in the milk hormone, prolactin, and chronic medical illnesses . Occasionally, no cause for anovulation may be identified.
Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among females, producing symptoms in approximately 5% to 10% of women of reproductive age. Such symptoms should include at least two of three of the following: (1) irregular menstrual cycles, (2) clinical and or biochemical (through laboratory assessment) hyperandrogenism, and (3) polycystic appearing ovaries on ultrasound. Notably, PCOS is generally a diagnosis of exclusion, which means that all other causes for the presenting symptoms should be excluded. Additionally, up to 20% of women without PCOS will have polycystic appearing ovaries on ultrasound.
PCOS has both reproductive and medical consequences to the affected woman. From a reproductive standpoint, the woman may suffer from anovulatory infertility. From a medical standpoint, affected women are at an increased risk for obstructive sleep apnea, depression, insulin resistance, type 2 diabetes, and metabolic syndrome. As such, women with polycystic ovary syndrome should be screened for these outcomes on a regular basis.