The External Genitalia Score (EGS): A European Multicenter Validation Study

Context Standardized description of external genitalia is needed in the assessment of children with atypical genitalia. Objectives To validate the External Genitalia Score (EGS), to present reference values for preterm and term babies up to 24 months and correlate obtained scores with anogenital distances (AGDs). Design, Setting A European multicenter (n = 8) validation study was conducted from July 2016 to July 2018. Patients and Methods EGS is based on the external masculinization score but uses a gradual scale from female to male (range, 0–12) and terminology appropriate for both sexes. The reliability of EGS and AGDs was determined by the interclass correlation coefficient (ICC). Cross-sectional data were obtained in 686 term babies (0–24 months) and 181 preterm babies, and 111 babies with atypical genitalia. Results The ICC of EGS in typical and atypical genitalia is excellent and good, respectively. Median EGS (10th to 90th centile) in males < 28 weeks gestation is 10 (8.6–11.5); in males 28–32 weeks 11.5 (9.2–12); in males 33–36 weeks 11.5 (10.5–12) and in full-term males 12 (10.5–12). In all female babies, EGS is 0 (0-0). The mean (SD) lower/upper AGD ratio (AGDl/u) is 0.45 (0.1), with significant difference between AGDl/u in males 0.49 (0.1) and females 0.39 (0.1) and intermediate values in differences of sex development (DSDs) 0.43 (0.1). The AGDl/u correlates with EGS in males with typical genitalia and in atypical genitalia. Conclusions EGS is a reliable and valid tool to describe external genitalia in premature and term babies up to 24 months. EGS correlates with AGDl/u in males. It facilitates standardized assessment, clinical decision-making and multicenter research.