Penile diameter during puberty in boys: a retrospective analysis of longitudinally obtained data

Tanner staging is the standard for rating sexual maturation (SMR) in boys (pubic hair (PH) and genital (G) development). G staging is tripartite in nature and is prone to ambiguity because it is based upon somewhat vague visual cues that may lead to erroneous assessments and medical errors. Measurement of penile growth (penile girth or diameter) may provide an additional tool (in addition to the orchidometer) to make G staging more valid. Although studies on penile growth (either circumference of width) have been reported, none were longitudinal. Therefore, our objective was to compare penile development in boys - measured as penile diameter (PD) - to PH stage and testicular volume (TV) and secondarily to G stage; moreover, to do so on a longitudinal basis.

Charts of 61 boys, ages 6-21 years of age, who were seen longitudinally, were reviewed. Each boy had his PD and TV measured along with his PH and G stage assessed on a quarterly to semi-annual basis.

PD increased significantly among PH stages II, III, and IV only. PD increased significantly among G stages I, II, III and IV only. PD correlated well with TV. There were significant correlations between PD and TV in all PH stages. However, for G stage correlations were not significant for stages II, III, and IV. PH stage was a better predictor of PD than G stage.

Measuring PD may be another tool to help in objectifying male SMR during puberty and overcome the vagueness encountered with the visual SMR G stage scales.