Patterns of ovarian morphology in polycystic ovary syndrome: a study utilising magnetic resonance imaging

Objective To evaluate and compare MRI-based ovarian morphology in groups of women with polycystic ovary syndrome (PCOS) and controls. Methods All PCOS cases ( n = 44) had oligo-amenorrhoea and hyperandrogenism irrespective of ovarian morphology, and fulfilled NIH/Rotterdam diagnostic criteria for PCOS. All control women ( n = 40) had normal menses and normoandrogenaemia. All subjects were of white British/Irish origin and pre-menopausal. Group comparisons were based on independent-sample t tests. Polycystic ovarian morphology was defined by at least 12 follicles 2–9 mm in diameter and/or an ovarian volume greater than 10 cm 3 . Results Ovarian morphology differed significantly in PCOS cases and controls (follicle number geometric mean [SD range] 18.6 [9.9, 35.0] vs 6.6 [3.1, 14.2], unadjusted P = 1.3 × 10 −16 ; calculated ovarian volume 8.8 cm 3 [5.0, 15.5] vs 5.1 cm 3 [2.5, 10.3], unadjusted P = 3.0 × 10 –7 ; peripheral follicle location in 55% vs 18% of ovaries, P = 7.9 × 10 –6 ; visible central ovarian stroma in 61% vs 24% of ovaries, P = 2.3 × 10 –5 ). Follicle number and calculated ovarian volume were not concordant with clinical/biochemical assignment of PCOS/control status in 36 (23%) and 52 (34%) of ovaries, respectively. Conclusion Ovarian morphology overlaps in PCOS cases and controls, emphasising the importance of considering clinical/biochemical presentation together with imaging ovarian morphology in the diagnosis of PCOS.