Anovulation
| Anovulation | |
|---|---|
| Classification and external resources | |
| Specialty | urology |
| ICD-10 | N97.0 |
| ICD-9-CM | 628.0 |
| eMedicine | med/146 |
| MeSH | D000858 |
Anovulation is when the ovaries do not release an oocyte during a menstrual cycle. Therefore, ovulation does not take place. However, a woman who does not ovulate at each menstrual cycle is not necessarily going through menopause. Chronic anovulation is a common cause of infertility.
In addition to the alteration of menstrual periods and infertility, chronic anovulation can cause or exacerbate other long term problems, such as hyperandrogenism or osteopenia. It plays a central role in the multiple imbalances and dysfunctions of polycystic ovary syndrome.
During the first two years after menarche 50% of the menstrual cycles could be anovulatories.
It is in fact possible to restore ovulation using appropriate medication, and ovulation is successfully restored in approximately 90% of cases. The first step is the diagnosis of anovulation. The identification of anovulation is not easy; contrary to what is commonly believed, women undergoing anovulation still have (more or less) regular periods. In general, patients only notice that there is a problem once they have started trying to conceive.
Temperature charting is a useful way of providing early clues about anovulation, and can help gynaecologists in their diagnosis.
The World Health Organization criteria for classification of anovulation include the determination of oligomenorrhea (menstrual cycle >35 days) or amenorrea (menstrual cycle > 6 months) in combination with concentration of prolactin, follicle stimulating hormone (FSH) and estradiol (E2). The patients are classified as WHO1 (15%) - hypo-gonadotropic, hypo-estrogenic, WHO2 (80%) - normo-gonadotropic, normo-estrogenic, and WHO3 (5%) - hyper-gonadotropic, hypo-estrogenic. The vast majority of anovulation patients belong to the WHO2 group and demonstrate very heterogeneous symptoms ranging from anovulation, obesity, biochemical or clinical hyperandrogenism and insulin resistance.
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