Polycystic ovary syndrome : relationship between insulin sensitivity, sex hormone levels and ovarian stromal blood flow

Polycystic ovary syndrome (PCOS) is the most common cause of menstrual disorders, and is characterized by chronic anovulation, hyperandrogenism and infertility. In recent years, it has become apparent that PCOS is also associated with hyperinsulinemia that is probably central to the pathogenesis of PCOS. As a peculiar vascular pattern has been reported to be present in PCOS, the aim of this study was to investigate intraovarian stromal vascularization in PCOS patients and its possible correlation with sex hormones, gonadotropins and insulin levels. Twenty-eight oligomenorrheic or amenorrheic patients with PCOS and 14 eumenorrheic women with a PCOS-like ovarian pattern undergoing endocrine screening and ultrasound color Doppler intraovarian blood flow were recruited to the study. Ten healthy women with regular menses represented the control group. Hormonal assays (follicle-stimulating hormone (FSH), luteinizing hormone (LH), androstenedione, testosterone, sex hormone-binding globulin (SHBG) and estradiol), oral glucose tolerance test (OGTT), baseline and glucose-induced insulin levels, and transvaginal ultrasonographic and color Doppler analysis (pulsatility index (PI), resistance index (RI) and velocity (Vmax) of ovarian stromal flow) were performed in all participants in the early proliferative phase. Endocrine values showed significant differences in PCOS patients compared with PCOS-like women and controls, while PI and RI indices were significantly higher in controls. PCOS patients were divided into hyperinsulinemic (n = 16) and normoinsulinemic (n = 12). Androstenedione was significantly higher (p < 0.01) in the hyperinsulinemic than in the normoinsulinemic patients and controls, while SHBG was significantly (p < 0.01) lower in the hyperinsulinemic group. Analysis of color Doppler intraovarian vascularization showed a significantly lower RI and a higher Vmax in the hyperinsulinemic subjects than in the normoinsulinemic PCOS patients and controls. An increased stromal blood flow was observed in the PCOS and PCOS-like patients by transvaginal color Doppler evaluation, but this technique is not able to differentiate these two similar ovarian patterns. However, hyperinsulinemic PCOS patients had an increased vascularity of the ovarian stroma. A strong correlation between hyperinsulinemia, hyperandrogenism and low SHBG levels was evidenced, and a hyperinsulinemia-induced mechanism for ovarian stromal angiogenesis is discussed.