Editing External Genital Anomalies in Boys (section)

==== Micropenis ====
* '''Definition of micropenis: a normally formed penis that is at least 2.5 standard deviations (SD) below the mean size in stretched length for age'''
** '''Stretched penile length correlates more closely with erectile length than does the relaxed penile length''' and should be compared with standards for penile length
** '''Micropenis in the full-term neonate is stretched penile length <1.9 cm long'''
* '''Causes'''
** See CW11 Box 146-1: Etiology of Micropenis
** '''Results from a hormonal abnormality that occurs after 14 weeks of gestation'''
** '''Hypogonadotropic hypogonadism (most common cause)'''
*** Failure of the hypothalamus to produce adequate quantities of gonadotropin-releasing hormone (GnRH) can occur in '''Prader-Willi syndrome, Kallmann syndrome (genital-olfactory dysplasia), Laurence-Moon-Biedl syndrome, and the CHARGE association'''
** '''Hypergonadotropic hypogonadism (primary testicular failure)'''
** '''Idiopathic'''
** Often associated with major chromosomal defects, including: Klinefelter syndrome (47,XXY) and other X polysomy syndromes, deletions, translocations, and trisomy involving chromosomes 8, 13, and 18
* '''Initial evaluation of a child with micropenis includes a history, physical examination, and a karyotype at birth.'''
* '''The ratio of the length of the penile shaft to its circumference is usually normal, but occasionally the corpora cavernosa are severely hypoplastic. The testes are usually small and frequently cryptorchid, whereas the scrotum is usually fused and often diminutive'''
* '''Although ultimate penile size may be below the normal range, men born with micropenis have male gender identity and most have satisfactory sexual function'''