Impact of the newly recommended antral follicle count cutoff for polycystic ovary in adult women with polycystic ovary syndrome.

Study Question: What is the impact of the newly recommended antral follicle count (AFC) cutoff for polycystic ovary (PCO) on the diagnostic status of polycystic ovary syndrome (PCOS)?

Summary Answer: Among patients with phenotypes requiring the presence of PCO for diagnosis, approximately half (48.2%) were excluded from having PCOS based on the new AFC cutoff, although these excluded women had worse metabolic and hormonal profiles than the controls and were indistinguishable from the remaining patients with regard to major hormonal and metabolic parameters.

What Is Known Already: In the Rotterdam criteria, PCO is defined as either 12 or more follicles measuring 2-9 mm in diameter or an increased ovarian volume >10 cm3. Recently, an international PCOS guideline development group recommended an AFC threshold for PCO of ≥20 in adult women when using transducers with a high-resolution frequency, including 8 MHz.

Study Design, Size, Duration: The current study used a case control design.

Participants/materials, Setting, Methods: PCOS was diagnosed according to the Rotterdam criteria. Ultrasonography examinations were conducted with wide band frequency (5-9 MHz) transvaginal transducers and the centre frequency was 8 MHz. In patients who show both irregular menstruation and hyperandrogenism (HA), a diagnosis of PCOS can be made irrespective of the ovarian criteria change. Patients who were diagnosed according to HA and PCO (n = 86) or irregular menstruation and PCO (n = 443) were initially included among a total of 1390 adult women with PCOS (aged 20-40 years). Regardless of the AFC, if the ovarian volume is ≥10 cm3, a diagnosis of PCO can still be made. Thus, only patients who had an ovarian volume of <10 cm3 were analysed. Subjects who had an AFC of 12-19 and an ovarian volume <10 cm3 were designated as the 'low AFC group' (n = 255) and were the main focus of the study because they were excluded from having PCOS based on the new cutoff. Subjects with an AFC ≥20 and an ovarian volume <10 cm3 were designated as the 'high AFC group' (n = 101). A total of 562 premenopausal women without PCOS were enrolled as controls.

Main Results And The Role Of Chance: Among patients with irregular menstruation and PCO or HA and PCO phenotypes, approximately half (48.2%, 255/529) were excluded from having PCOS, which corresponded to one-fifth (18.3%, 255/1390) of the total adult patients. However, compared to the control group, these excluded women had worse metabolic profiles and were more androgenised. Notably, they were indistinguishable from the 'high AFC group' with regard to major hormonal and metabolic parameters (BMI and diabetic classification status, and the prevalence of insulin resistance, metabolic syndrome and HA).

Limitations, Reasons For Caution: We cannot exclude the possibility of inter- and intraobserver variation in the evaluation of AFC.

Wider Implications Of The Findings: With the newly recommended follicle count cutoff, a substantial proportion of women with PCOS might be classified as not having PCOS despite visiting a hospital due to irregular menstruation or hyperandrogenic symptoms. A practical approach to them would involve controlling the menstrual or hyperandrogenic symptoms in hand and regularly evaluating them regarding newly developed or worsening PCOS-related symptoms or metabolic abnormalities.

Study Funding/competing Interest(s): This study was supported by a grant from the Seoul National University Hospital Research Fund (No. 2520140090), Republic of Korea. The authors have no conflicts of interest to disclose.

Trial Registration Number: Not applicable.