Hartman SJ, Prieto JM, Naheedy JH, et al. - Ultrasound-based predictors of ovarian torsion in girls without an adnexal mass were investigated and a set of normal values for ovarian volume ratio (OVR) was established. They conducted a retrospective review of all premenarchal patients ≥ 3 years of age with normal pelvic ultrasound and compared the findings with those in a group of premenarchal girls presenting with torsion in the absence of an adnexal mass. Pelvic ultrasound evaluation was performed on 504 premenarchal girls with a normal examination. Observations suggest that in premenarchal girls without an adnexal mass, OVR is an excellent predictor of ovarian torsion. Unlike ovarian width, OVR does not increase with age, and a cutoff OVR > 2.5 displays high sensitivity and specificity for recognizing ovarian torsion in this population.