The "rule of 10" in Polycystic Ovary Syndrome (PCOS) refers to diagnostic criteria based on ovarian characteristics observed during ultrasound: specifically, either 10 or more follicles per section in at least one ovary, and/or an ovarian volume of 10 mL or greater in at least one ovary, when evaluated in the absence of a corpus luteum, cysts, or a dominant follicle.
Understanding the Rule of 10 in PCOS Diagnosis
The Rotterdam criteria are commonly used for diagnosing PCOS, requiring the presence of at least two of the following three features:
- Oligo- or anovulation: Irregular or absent menstrual periods.
- Clinical and/or biochemical signs of hyperandrogenism: Excess male hormones, leading to symptoms like hirsutism (excess hair growth), acne, and elevated androgen levels in blood tests.
- Polycystic ovaries: Visualized on ultrasound.
The "rule of 10" falls under the third criterion, polycystic ovaries, and serves as a specific parameter for defining this characteristic.
Parameters of the "Rule of 10"
Here's a breakdown of the criteria:
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Follicle Number per Section (FNPS) ≥ 10: This refers to the number of follicles (small sacs containing eggs) visible in a single ultrasound section of the ovary. Having 10 or more follicles in at least one ovary meets this part of the criterion.
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Ovarian Volume ≥ 10 mL: This measures the overall size of the ovary. An ovarian volume of 10 mL or greater in at least one ovary, when evaluated in the absence of a corpus luteum (structure formed after ovulation), cysts (fluid-filled sacs), or a dominant follicle (a mature follicle ready to release an egg), satisfies this part of the criterion.
Important Considerations
- The ultrasound evaluation should be performed by a trained professional.
- The presence of a corpus luteum, cyst, or dominant follicle can affect the measurement of ovarian volume and follicle count, so their absence must be confirmed to accurately apply the "rule of 10".
- This is just one criterion for diagnosing PCOS, and a diagnosis requires the presence of at least one other criterion (oligo- or anovulation or hyperandrogenism).
- This rule aids in the diagnosis of PCOS; however, clinical correlation with the patient's overall presentation is crucial.
