From the Guidelines
The role of ovarian ultrasound in diagnosing Polycystic Ovary Syndrome (PCOS) is to identify polycystic ovarian morphology, characterized by 20 or more follicles per ovary, measuring 2-9 mm in diameter, or an ovarian volume greater than 10 mL, as recommended by the most recent international guidelines 1. When diagnosing PCOS using ovarian ultrasound, it is essential to consider the following key points:
- The threshold for polycystic ovarian morphology (PCOM) should be revised regularly with advancing ultrasound technology, and age-specific cut off values for PCOM should be defined 1.
- The transvaginal ultrasound approach is preferred in the diagnosis of PCOS, if sexually active and if acceptable to the individual being assessed 1.
- Using endovaginal ultrasound transducers with a frequency bandwidth that includes 8MHz, the threshold for PCOM should be on either ovary, a follicle number per ovary of ≥20 and/or an ovarian volume ≥ 10ml, ensuring no corpora lutea, cysts or dominant follicles are present 1.
- In patients with irregular menstrual cycles and hyperandrogenism, an ovarian ultrasound is not necessary for PCOS diagnosis; however, ultrasound will identify the complete PCOS phenotype 1. The diagnostic accuracy of ultrasonographic markers in PCOS diagnosis has been evaluated in recent studies, with follicle number per ovary (FNPO) and ovarian volume (OV) being the most commonly used markers 1. Some of the key findings from these studies include:
- FNPO ≥20 follicles had a sensitivity of 87.64% and specificity of 93.74% for PCOS diagnosis 1.
- OV ≥10 cm had a sensitivity of 82.56% and specificity of 78.95% for PCOS diagnosis 1. It is crucial to note that the diagnosis of PCOS should be based on a combination of clinical, biochemical, and ultrasonographic criteria, rather than relying solely on ultrasound findings 1. Additionally, the limitations and challenges of using ultrasound in PCOS diagnosis, such as operator and equipment-dependent variability, and the potential for overlap with other conditions, should be considered 1.
From the Research
Role of Ovarian Ultrasound in Diagnosing PCOS
- Ovarian ultrasound is a crucial diagnostic tool for Polycystic Ovary Syndrome (PCOS) as it helps identify polycystic ovarian morphology (PCOM) 2, 3, 4, 5.
- The diagnosis of PCOS relies on clinical, biological, and morphological criteria, with ultrasonography playing a significant role in assessing follicle excess and ovarian volume 3, 5.
- Studies have shown that the previously proposed threshold value of 12 follicles per ovary is no longer valid, and newer threshold values of 19 follicles 2 or 25 follicles 3, 5 are recommended for defining PCOM.
- Ovarian volume (OV) is also considered a marker of PCOM, with a threshold of ≥10 ml 3, 5.
- The use of anti-Müllerian hormone (AMH) levels as a surrogate marker for PCOM has been proposed, but standardization of AMH assays is needed before it can be routinely used for clinical practice and research 2, 3, 4.
- Transvaginal ultrasonography is the preferred method for assessing ovarian morphology, and the use of newer technology with higher transducer frequencies (≥8 MHz) is recommended for accurate follicle counting 3, 5.
Diagnostic Thresholds for PCOS
- The diagnostic potential of follicle number per ovary (FNPO) is higher than that of follicle counts in a single cross-section (FNPS) and ovarian volume (OV) 5.
- An FNPO threshold of 26 follicles has been shown to have the best compromise between sensitivity (85%) and specificity (94%) for diagnosing PCOS 5.
- The use of FNPS and OV as diagnostic criteria may not be as accurate as FNPO, but they can still be useful in certain situations 5.
Clinical Implications
- The diagnosis of PCOS using ovarian ultrasound criteria has significant clinical implications, as it can help identify women at risk of metabolic and reproductive complications 3, 4, 6.
- The use of standardized diagnostic criteria for PCOS can help improve the accuracy of diagnosis and treatment outcomes 3, 6.