Polycystic ovarian syndrome (PCOS) is a chronic anovulation syndrome associated with androgen excess. An alternative diagnostic term, hyperandrogenic anovulation (HA) has been proposed as more accurate and potentially less confusing (the ovarian feature is of multiple follicles, not cysts)13. At this stage, however, PCOS remains the term that is widely known and used.
The diagnosis is made on the combined clinical, biochemical and sonographic grounds. The revised 2003 ASRM/ESHRE Rotterdam consensus criteria 4 require two of the following three criteria for the diagnosis:
- oligo- or anovulation
- hyperandrogenism (clinical or biochemical) and
- follicle count on imaging
Subsequently, the Androgen Excess and PCOS society (AE-PCOS) 9 specified a similar set of criteria for diagnosing PCOS but added that PCOS should be seen primarily be seen as a disorder of androgen excess or hyperandrogenism. The criteria set forward was:
- the presence of hyperandrogenism (clinical and/or biochemical)
- ovarian dysfunction (oligo-anovulation and/or polycystic ovaries)
- exclusion of related disorders
The estimated prevalence is ~6% (range 4-8%) of women of reproductive age but this varies (up to 20%) depending on the diagnostic criteria used 11.
The classic triad of PCOS is:
In addition to this, patients may have infertility, acne, male pattern balding or biochemically show increased androgen levels.
Luteinizing hormone (LH) is usually increased and follicle stimulating hormone (FSH) can be normal or decreased 10.
Normally premenopausal LH:FSH is 1:1. In PCOS it may be >2:1 or >3:1.
Anti-Müllerian hormone (AMH) levels are generally increased.
- subfertility and recurrent pregnancy loss.
- long-term increased risk of
- type 2 diabetes
- cardiovascular disease
- endometrial cancer 6
- women with polycystic ovarian morphology are at increased risk of OHSS when undergoing IVF, regardless of whether they have PCOS15.
Current recommended sonographic criteria for multifollicular ovarian morphology:
- 25 or more follicles per ovary (superseding the earlier Rotterdam criteria of 12 or more follicles) 14
- increased ovarian size (>10 cc): less sensitive than the follicle number criteria, but has a role when image resolution does not allow accurate follicle count, e.g. transabdominal scanning, older equipment
Other morphological features include:
- hyperechoic central stroma
- peripheral location of follicles: which can give a string of pearl appearance
- follicles of similar size measuring 2-9 mm
The presence of a single PCO is sufficient to provide the diagnosis 2.
Ovaries may be normal in PCOS, and conversely, polycystic ovaries may be seen in women without the syndrome. Diagnosis requires correlation with features of hyperandrogenism and oligo-anovulation.
MRI is not considered to be a first-line investigation in the investigation of PCOS. The ultrasound criteria detailed above may be applied to MRI (follicle count and ovarian volume), but there is a great deal of overlap between healthy people and patients with PCOS. The presence of abundant hypointense central stroma with small peripheral T2 hyperintense cysts is said to be the characteristic appearance 16,17.
History and etymology
The syndrome was first described by I.F. Stein and M.L. Leventhal in 1935 7.
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