A diagnostic model of idiopathic central precocious puberty based on transrectal pelvic ultrasound and basal gonadotropin levels.

To establish a diagnostic model of idiopathic central precocious puberty on the basis of transrectal pelvic ultrasound and basal gonadotropin. A total of 669 girls with Tanner breast development stage II were enrolled in this study from January 2015 to December 2018. The participants were divided into the ICPP group and the premature thelarche group. We analyzed various variables, including age at initial diagnosis, basal luteinizing hormone levels, the long diameter of the uterus, the transverse diameter of the uterus, the anterior-posterior diameter of the uterus, the volume of the uterus, maximum ovarian diameter, average ovarian volume, maximum ovarian volume, number of follicles (≥4 mm), maximum follicular diameter, endometrial thickness, and vaginal wall thickness. The following diagnostic model was established: Y=-14.123 + 0.630 × age at initial diagnosis + 1.119 × transverse diameter of the uterus + 1.278 ×  anterior-posterior diameter of the uterus + 0.637 × average ovarian volume + 1.316 × maximum ovarian diameter + 0.146 ×number of follicles ≥4 mm + 2.925 × endometrial thickness + 0.559 × basal luteinizing hormone value. The area under curve was 0.922, sensitivity was 84.9%, and specificity was 86.2%. Basal LH levels and transrectal pelvic ultrasound should be applied together to improve the accuracy of diagnosis in ICPP.