Effectiveness of Pelvic Ultrasonography in the Diagnosis of Central Precocious Puberty and its Differentiation from Similar Conditions

Background: Differentiation of patients with central precocious puberty (CPP) from healthy individuals and patients with CPP-like conditions [isolated premature thelarche (IPT) and isolated premature adrenarche (IPA)] is important for selecting an appropriate treatment. The gonadotropin-releasing hormone stimulation test is used as the gold standard for differentiating CPP from other conditions. Despite its high specificity, this test has disadvantages, such as low sensitivity, time-consuming sampling, and need for multiple blood samples. Objectives: This study aimed to investigate the use of pelvic ultrasonography (US) and its parameters in distinguishing CPP patients from those with similar conditions and healthy individuals. Methods: In this case-control study, a total of 183 patients, who were referred to the endocrinology department of Ali Asghar Hospital in Tehran, Iran for the evaluation of CPP, were recruited cconsecutively from 2015 to 2019. All the participants were Iranians and classified based on the clinical and laboratory findings. Pelvic US parameters were evaluated in all groups. One-way analysis of variance (ANOVA) was used to compare the mean values of continuous variables between the groups. Moreover, a post-hoc test was performed for pairwise comparisons between the groups if the result of ANOVA test was statistically significant. Finally, the receiver-operating characteristic (ROC) curve analysis was performed to determine the best cutoff points for US parameters. Results: Of 183 children, 62 were allocated to the control group (33.87%), 93 to the CPP group (50.81%), 16 to the IPT group (8.74%), and 12 to the IPA group (6.55%). The results showed no significant difference between the groups regarding chronological age and body mass index, while the bone age (107.76 ± 19.81 months) (P < 0.001) and height (129.53 ± 8.97 cm) were significantly higher in the CPP group compared to the other groups (P = 0.003). All US parameters were significantly different between the CPP and control groups. There were also significant differences between CPP patients and those with IPT and IPA in terms of all parameters, except for the cervical anteroposterior diameter and ovarian volume. The best parameters for differentiating CPP from other conditions were the uterine volume (cutoff value, 1.40; 75.27% sensitivity; 75.56% specificity), uterine transverse diameter (cutoff value, 13.5 mm; 72.04% sensitivity; 71.11% specificity), and fundus/cervix (F/C) ratio (cutoff value, 0.98; 78.49% sensitivity; 70% specificity). Conclusions: The pelvic US parameters can improve the diagnosis of CPP and play an auxiliary role in distinguishing the treatment needed. Based on the findings, the best diagnostic parameter and its cutoff value can vary depending on ethnicity and type of study.