September 19, 2022

Polycystic Ovarian Syndrome Awareness Month


Ultrasound Updates: Revised Diagnostic Tools and Criteria for Polycystic Ovarian Syndrome

By: Megan Euerle

Editor’s Note: Though initially described in 1930s medical literature, polycystic ovaries were identified at least a century prior and are a diagnostic feature of polycystic ovarian syndrome (PCOS). Research continues to emerge about the disorder, now considered the most common endocrine abnormality among women of reproductive age. [1] As a syndrome — determined by presenting symptoms and features without a single diagnostic test — it is critical to establish (and revise, if necessary) reliable diagnostic tools and criteria to define PCOS. As part of our series during PCOS Awareness Month, we are featuring a former FACTS elective student Megan Euerle’s summary of 2013 research published in Fertility and Sterility on updated ultrasound criteria for PCOS, including thresholds for follicle population and ovarian volume.



Polycystic ovarian syndrome (PCOS) is a common cause of female infertility and has many clinical implications, such as irregular menstrual cycles, insulin resistance, obesity, and other health risks. [1] As a result, PCOS may require life-long treatment, and the reliability of diagnostic tools and criteria are fundamental to effective patient care. Ultrasound evaluation is one such diagnostic tool.

Due to the increasing prevalence of polycystic ovaries in otherwise healthy women with regular menstrual cycles, the ultrasonographic criteria for polycystic ovaries established by the 2003 Rotterdam consensus (12 follicles per one ovary) has come into question as an appropriate threshold for a PCOS diagnosis.[2] Therefore, the validity of using polycystic ovaries as a PCOS marker has also come into question. This 2013 study by Lujan et al. [3] addresses the utility of ultrasound in distinguishing between the normal ovary and PCOS by providing updated guidelines for ultrasound thresholds for both follicle count and ovarian volume. The authors address the thresholds provided by previous studies and their limitations, as well as the relevance of advancements in imaging technology to assess these markers.

“This 2013 study by Lujan et al. addresses the utility of ultrasound in distinguishing between the normal ovary and PCOS by providing updated guidelines for ultrasound thresholds for both follicle count and ovarian volume.”


The researchers conducted a diagnostic test study of 168 women: 70 healthy controls and 98 diagnosed with PCOS. The participants were prospectively evaluated by transvaginal ultrasound, and the resulting data were analyzed to determine appropriate diagnostic thresholds for follicle number per ovary (FNPO), follicle number per cross section (FNPS), and ovarian volume (OV). Intra- and inter-observer reliability in using the determined criteria were also addressed in the study. Researchers analyzed serial images taken throughout the entire ovary rather than just static images, and follicles were counted using a grid system imposed on the ultrasound images. [3]

Research participants ranged from 18 to 35 years of age and did not use hormonal contraception, insulin sensitizers, or fertility medications within three months prior to enrollment in the study. The subset of women diagnosed with PCOS all met the NIH criteria of both oligo-amenorrhea and hyperandrogenism. [3]


Lujan et al. presented a comparison of healthy female clinical, hormonal, and ultrasonographic imaging profiles with PCOS patient profiles. Age was comparable between the control and PCOS groups, but BMI and hirsutism scores were both significantly higher in the PCOS group (P < 0.001). Testosterone levels and free androgen indexes were also higher in the PCOS group (P = 0.007) and (P < 0.001), respectively. In comparison with the healthy control group, women diagnosed with PCOS also reported longer intervals between menses (P < 0.001).

Regarding the ultrasound findings, FNPO, FNPS, and OV were all found to be higher in women with PCOS compared to the healthy women (P < 0.001). FNPO had the highest diagnostic potential of the three factors; the FNPO threshold found to maximize sensitivity and specificity in differentiating PCOS from control was 26 follicles per ovary (85% sensitivity and 94% specificity). Thus, the study proposed a new FNPO criteria of more than double the Rotterdam criteria for PCOS: 26 follicles, versus 12. Observers also ranked their levels of diagnostic confidence with each potential marker of PCOS (FNPO, FNPS, and OV) on a 5-point scale, and reported the highest levels of confidence when using the FNPO criteria for diagnosis. [3]

“The study proposed a new follicle number per ovary (FNPO) diagnostic criteria of more than double the Rotterdam criteria for PCOS: 26 follicles, versus 12.”


The study aimed to revisit the ultrasound criteria for PCOS and determine appropriate thresholds of follicle number per ovary to more accurately distinguish between healthy women and women with PCOS. Researchers also took advantage of newer and more advanced ultrasound and imaging technology, as well as the organized grid-based image analysis to count follicles in serial images spanning the entire ovary. Another advantage of the study approach was the recruitment of a control group alongside a PCOS group; previous research typically utilized data from referred hospital patients or women seeking fertility treatments. [3]

In light of the study’s advantages over prior studies, newer ultrasound technology, and the increased prevalence of polycystic ovaries among otherwise healthy women with regular menstrual cycles — the authors proposed a revision of the ultrasound criteria for PCOS. They asserted that features found on ultrasound, such as FNPO, still hold substantial diagnostic potential in reliably differentiating those with PCOS from healthy women of the general population, but propose a new FNPO threshold of 26 follicles. [3]

This study sparks discussions of the utility of ultrasound in accurate diagnosis, which can still be a valuable guide on the path to proper treatment. Despite encouraging data from Lujan et al. the literature review by Azziz et al. [1] emphasizes that the diagnostic criteria for PCOS should be based on robust data and further investigation is necessary to more precisely define and diagnose this disease.

PCOS also commonly occurs alongside a host of other health issues. An understanding of what defines the disease is necessary both for the patient and her physician in determining the most effective course of treatment.

As a future physician, I recognize the importance of revising a diagnostic approach as collective information and understanding about a disease increases. For women, the implications of PCOS are often a mystery. My personal experience with friends, family members, and patients with PCOS is that they often feel in the dark about what their future might hold regarding their fertility and various other health issues. For these women and their families, the importance of accurate, up-to-date diagnostic criteria cannot be overstated. In addition to reliable diagnostic criteria, fertility awareness-based methods (FABMs) can also facilitate the diagnosis and management of PCOS, as well as women’s understanding of what is happening with their cycle.  A woman’s chart may reveal abnormal biomarker patterns associated with PCOS and provide guidance for FABM-trained clinicians to begin targeted lab workups and medical therapy to treat the syndrome. As the leading cause of anovulatory infertility, [4] it is critical to accurately diagnose and treat PCOS. Overall, this study emphasized the importance of revisiting diagnostic criteria, which could have a significant impact on the future of patient care.

“A woman’s chart may reveal abnormal biomarker patterns associated with PCOS and provide guidance for FABM-trained clinicians to begin targeted lab workups and medical therapy to treat the syndrome.”


[1] Azziz R, Carmina E, Dewailly D, et al.; Task Force on the Phenotype of the Polycystic Ovary Syndrome of The Androgen Excess and PCOS Society. The Androgen Excess and PCOS Society criteria for the polycystic ovary syndrome: the complete task force report. Fertil Steril. 2009 Feb;91(2):456-88. doi: 10.1016/j.fertnstert.2008.06.035. Epub 2008 Oct 23. PMID: 18950759.

[2] Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group. Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome. Fertil Steril. 2004 Jan;81(1):19-25. doi: 10.1016/j.fertnstert.2003.10.004. PMID: 14711538.

[3] Lujan ME, Jarrett BY, Brooks ED, Reines JK, Peppin AK, Muhn N, Haider E, Pierson RA, Chizen DR. Updated ultrasound criteria for polycystic ovary syndrome: reliable thresholds for elevated follicle population and ovarian volume. Hum Reprod. 2013 May;28(5):1361-8. doi: 10.1093/humrep/det062. Epub 2013 Mar 15. PMID: 23503943.

[4] Dennett CC, Simon J. The role of polycystic ovary syndrome in reproductive and metabolic health: overview and approaches for treatment. Diabetes Spectr. 2015;28(2):116-120. doi:10.2337/diaspect.28.2.116


Megan Euerle

Megan Euerle graduated from Des Moines University College of Osteopathic Medicine in 2022.. She is currently pursuing a pediatrics residency and is interested in providing preventative health care to children and adolescents. She took the FACTS elective to gain a better understanding of FABMs so that she might help her patients explore all healthy options within the realm of reproductive health.

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