What is micropenis?


Dr. Greene’s Answer:

Micropenis (sometimes also referred to as microphallus) is a penis that is more than 2.5 standard deviations below the average size for age. In a newborn, a stretched penile length less than ¾ inch (1.9 cm) is micropenis.

Micropenis is a hormonal problem that takes place sometime after 14 weeks gestation when the penis has already formed. Hormone levels need to be checked. A boy’s chromosomes should also be checked to see if there is an underlying genetic syndrome. An MRI may be needed to look at the hormone secreting glands. If the penis grows when a 3 month-trial of testosterone is given, the outlook is good for normal adult penis size and function.

If micropenis does not respond to testosterone stimulation, the difficult question of re-assigning gender arises. This decision has been made even more difficult by conflicting and changing recommendations of experts in the field. (Van Wyk JJ, Calikoglu AS, Should boys with micropenis be reared as girls? Journal of Pediatrics. 1999; 134(5)) At one time, gender re-assignment was the routine choice, even though it involves castration, surgical reconstruction, estrogen supplements, and huge emotional issues for the child and family. (Many people based their opinions on the case of a baby boy whose penis was accidentally amputated during circumcision. When he was 22 months old, he was castrated and reassigned a female sex. He had surgery to make his genitals appear female. He was raised as a girl. At puberty, he was given estrogens to promote breast growth. Reports said that he had a very good adjustment to the female sex, but it later became clear that from an early age he had rejected the idea that he was a girl. During his teen years, he insisted on switching back to living as a man. He later married as a man. (Diamond M, Sigmundson HK. Sex reassignment at birth. Long-term review and clinical implications. Arch Pediatr Adolesc Med 1997;151:298-304.)

The most recent consensus statement on the management of intersex disorders recommends raising boys with micropenis as males (i.e., no gender re-assignment). The reasoning is that this decision prevents surgery while allowing for fertility (Lee, Peter, “Consensus Statement on Management of Intersex Disorders,” Pediatrics, v118:2, August 2006, e488-e500).

Recent long-term studies of micropenis have found that even if the penis remains small, most boys-raised-as-boys end up as sexually active, heterosexual males who stand to urinate, have a strong male identity, normal erectile function, and who enjoy sex. (Reilly JM, Woodhouse CR. Small penis and the male sexual role. J Urol 1989;142:569-71.) Their partners also report sexual satisfaction. (van Seters AP, Slob AK. Mutually gratifying heterosexual relationship with micropenis of husband. J Sex Marital Ther 1988;14:98-107.) Teasing from peers can be a real problem, though. A penile prosthesis may help.

Adults who have themselves had intersex issues argue strongly against reassignment before the child is old enough to choose. (Van Wyk JJ, Calikoglu AS, Should boys with micropenis be reared as girls? Journal of Pediatrics. May 1999. 134(5).) Their opinion should be listened to carefully.

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Dr. Alan Greene

Dr. Greene is the founder of DrGreene.com (cited by the AMA as “the pioneer physician Web site”), a practicing pediatrician, father of four, & author of Raising Baby Green & Feeding Baby Green. He appears frequently in the media including such venues as the The New York Times, the TODAY Show, Good Morning America, & the Dr. Oz Show.

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