Dr. Greene's Answer
When a penis appears absent or too small, we call the condition inconspicuous penis (Walsh: Campbell’s Urology, 7th ed., W. B. Saunders Company, 1998). I’ve seen this in a great many boys. Several very different situations are lumped into this category. I will describe webbed penis, concealed penis, trapped penis, micropenis, and absent penis.
A webbed penis is a normal-sized penis where the skin of the scrotal sack extends part way up the shaft of the penis. Boys can be born this way, or the condition can result from an over-exuberant circumcision where adhesions form between the scrotal skin and the penile skin. Webbed penis usually causes no problems (unless a routine circumcision is later performed). It is unlikely to get better as the child grows. Results with surgery, however, are excellent. (Casale AJ – Concealed penis in childhood: a spectrum of etiology and treatment. J Urol – 1999 Sep; 162(3 Pt 2): 1165-8).
A concealed penis is a normal-sized penis that lays hidden in the pubic fat pad. This condition is also called buried penis or hidden penis. Some children are born this way, and for some it happens after circumcision. It is common in infants and toddlers, and occasionally seen in older children and obese adolescents. If the penis can be easily exposed by gently pulling on it or by pressing down on the surrounding fat pad, then the situation will usually correct itself over time. Sometimes surgery is needed for concealed penis. Either way, results are excellent.
A trapped penis is a normal-sized penis that is partially stuck in the pubic fat pad. Children are not born with trapped penis; circumcision causes it. Routine circumcision of a webbed penis or circumcision when there is significant scrotal swelling (from a hydrocele or hernia) can lead to trapped penis. Scarring or adhesions trap the recessed penis in the fat pad. This condition can predispose children to urinary tract infections or urinary retention. Surgery is usually wise.
All of the above conditions have a penis of normal size. In determining size, the “stretched penile length” is far more important than the “relaxed length.” To evaluate penis size, stretch the penis gently and measure from the bone at the base all the way to the tip. Be sure to depress the surrounding fat pad to get all the way to the base. Here are the normal values:
Average Stretched Penile Length (Adapted from Feldman KW, Smith DW. Journal of Pediatrics. 1975; 86:395):
Mean +/- 1 SD (inches)
Mean – 2.5 SD (inches)
1.5 +/- 0.3
1.7 +/- 0.3
1.9 +/- 0.3
2.0 +/- 0.4
2.2 +/- 0.4
2.2 +/- 0.4
2.4 +/- 0.4
2.5 +/- 0.4
5.2 +/- 0.6