Penile Length and Testicular Volume in Newborns

To measure Penile length (PL) and Testicular volume (TV) in newborn boys for assessing genital abnormalities.

In a tertiary care setting, measurements of PL and TV were recorded from 480 babies born on alternate days except the weekend, at 24 to 72 h of life by one investigator with the same set of instruments. The penis was stretched to the point of increased resistance and the distance from the tip of the glans penis to the pubic ramus was measured as the stretched PL. Testicular volume was measured by a Prader orchidometer. Improvised beads made of plasticine were used for recording volumes <1 ml.

In the study cohort, 365 (76.04 %) were term babies. The mean PL was 34 ± 4.7 mm for the whole cohort while the corresponding value for mean TV was 0.6 ± 0.2 ml. The gestation age-wise percentile charts of PL and TV have been generated. There was modest positive correlation between PL and TV. Positive correlation was also observed between PL and TV and birth weight, body length, and head, chest and arm circumference. Both PL and TV showed statistically significant increase with gestational age. By the index data, the cut-off for suspecting abnormal penile length should be <24.5 or >45.5 mm for term babies.

The normative values generated can serve as reference standard in the diagnosis of penile length abnormalities in Indian babies and in clarifying issues of ambiguous genitalia and maldevelopment of male external genitalia.