Kim JJ, et al. - Researchers here investigated how the newly recommended antral follicle count (AFC) cutoff for polycystic ovary (PCO) affects the diagnostic status of polycystic ovary syndrome (PCOS). Diagnosis of PCOS was made according to the Rotterdam criteria. A diagnosis of PCOS can be made irrespective of the ovarian criteria change in patients who show both irregular menstruation and hyperandrogenism (HA). Among a total of 1,390 adult women with PCOS (aged 20–40 years), inclusion of patients who were diagnosed according to HA and PCO (n = 86) or irregular menstruation and PCO (n = 443) was done initially. A diagnosis of PCO can still be made regardless of the AFC, if the ovarian volume is ≥ 10 cm³. Thus, analysis of only patients who had an ovarian volume of < 10 cm³ was done. The ‘low AFC group’ (n = 255) comprised women with an AFC of 12–19 and an ovarian volume < 10 cm³; these were the main focus of the study as they were excluded from having PCOS based on the new cutoff. The ‘high AFC group’ (n = 101) comprised women with an AFC ≥ 20 and an ovarian volume < 10 cm³. Controls were a total of 562 premenopausal women without PCOS. Outcomes revealed that among patients with phenotypes requiring the presence of PCO for diagnosis, the new AFC cutoff led to exclusion of nearly half (48.2%) from having PCOS, although these excluded women exhibited worse metabolic and hormonal profiles than the controls and were indistinguishable from the remaining patients with regard to major hormonal and metabolic parameters.