Previous studies have established normal penile length for patient age
and stage of sexual development. To our knowledge penile length has o
nly been determined to date by measuring the stretched distance from t
he symphysis to the glans tip. Pilot studies at our institution showed
that ultrasound corpora cavernosa length determinations were possible
using a 7.5 MHz. linear transducer probe. To determine whether ultras
ound is a more accurate modality in assessing penile length, male subj
ects 0 to 24 months old with normal penile anatomy and palpably descen
ded testicles were enrolled in a prospective analysis. Longitudinal ul
trasound images of the flaccid penis were obtained from the dorsal sur
face. The whole corporeal bodies were easily imaged and measured. In a
blinded fashion a separate investigator performed a conventional stre
tched penile length determination. A total of 27 male subjects 1 week
to 22 months old was evaluated and 2 were excluded. Corpora cavernosa
measurements using ultrasound revealed a mean length of 32.3 +/- 4.7 m
m. (range 22.4 to 44.9). Stretched penile lengths of the same subjects
revealed a mean length of 46.8 +/- 8.2 mm. (range 31 to 63). Circumci
sion status (p = 0.036) and age (p < 0.001) significantly correlated w
ith stretched length determinations. Ultrasound measurements did not s
ignificantly vary with patient circumcision status or age. Penile leng
th and race were not correlated when using stretched or ultrasound mea
surements. Ultrasound determination of corporeal body length is possib
le in young subjects. From infancy to age 22 months ultrasound measure
ments are not significantly affected by age or the presence of foreski
n. Our experience suggests that corporeal body evaluation by ultrasoun
d may offer a more accurate assessment of functional penile length.