True ovarian volume is underestimated by two-dimensional transvaginal ultrasound measurement

ObjectiveTo investigate a possible difference between true ovarian volume and ovarian volume estimated with two-dimensional (2D) transvaginal ultrasound.DesignProspective clinical and laboratory study.SettingUniversity hospital research laboratory.Patient(s)Premenopausal girls and women from three Danish national fertility centers (A: n = 42; B: n = 6; C: n = 18), who had one entire ovary removed for cryopreservation of ovarian cortex.Intervention(s)Transvaginal 2D ultrasound measurement of ovarian volume before oophorectomy. True ovarian volume was obtained by weighing the ovary.Main Outcome Measure(s)Ovarian volume estimated by weight and ultrasound.Result(s)Ovarian tissue density was 1.00 g/mL. Mean ovarian volume by ultrasound vs. weight in the three groups was as follows: A: 6.3 mL vs. 7.8 mL; B: 5.4 mL vs. 6.8 mL; and C: 2.8 mL vs. 6.1 ml. Ovarian volume obtained by ultrasound was at least 27% smaller than the true ovarian volume.Conclusion(s)Ovarian volume was severely underestimated by transvaginal 2D ultrasound measurement.