Pediatric penile anthropometry nomogram: Establishing standardized reference values

Anthropometry of the penis holds significant cultural and clinical importance, reflecting male genital development and aiding in the early identification of abnormalities.

Objectives: To develop an age-related penile length nomogram for Indian children, to define a range of normalcy, and to develop age-matched controls for penile length assessment in managing conditions like hypospadias.

Methods: This is a cross-sectional study (Design) initiated post-Institute Ethics Committee clearance (Ethics) based on 1276 volunteers (boys) aged 1-14 years (Participants) presenting to a pediatric surgery clinic (Setting) for conditions not affecting penile length. Participants were registered for the study and their age(years), weight(kg), and stretched penile length (SPL in cm) were recorded (Intervention). Generalized additive models for Location, Scale, and Shape (GAMLSS/extension of LMS method) were used. Outcome measures included weight (mean/range) and SPL (mean/range/standard deviation/median/centiles). The four distribution parameters were modeled as non-parametric smoothing cubic-spline functions of x with Box-Cox Power Exponential (BCPE) distribution and centiles (3, 5, 10, 25, 50, 75, 90, 95, 97) were calculated for the stretched penile length.

Results: SPL increases with age (3.4 cm in a 1-year-old to 12.7 cm in a 14-year-old) of the child in a non-linear fashion (r = 0.67, p < 0.001). Centile curves showed two phases of steep SPL increase, at ages 2-4 years and 10-14 years, reflecting early childhood growth and pubertal spurt respectively.

Conclusions: This is the largest cross-sectional study on the pediatric SPL in the Indian population. The data will serve as a useful resource for both parents and physicians in assessing penile development and guiding patient management.