Jacob SL, et al. - In this prospective diagnostic utility study, researchers intended to determine if there is an association between anti-Müllerian hormone (AMH) and the severity of the phenotype of patients with polycystic ovary syndrome (PCOS) and whether AMH can act as a diagnostic marker for PCOS. Between June 2012 and May 2013, a consecutive series of women presenting to a tertiary infertility clinic (n = 164) plus a second series of women prepared for assisted conception treatments (n = 89) recruited. Using the Rotterdam criteria, PCOS was diagnosed. Using the Generation II assay (Beckman Coulter), AMH was measured. Findings revealed that serum AMH concentrations differed significantly in women with normal ovaries (13·2 pmol/l), polycystic ovary morphology (PCOM) alone (37·8 pmol/l) and PCOS (53·2 pmol/l). Data showed that serum AMH has the ability to act as a PCOS diagnostic test. They observed that follicle number, increasing cycle length and evidence of hyperandrogenism (HA) were all independently linked to serum AMH concentration. In addition, since its value increases with more pronounced phenotypes, different cut-off values must be used to distinguish patients with polycystic ovarian morphology (PCOM), HA and oligoanovulation (OA).