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- What are the features of prenatal virilization in a 46 , XX newborn?
The features that suggest prenatal virilization in a 46,XX newborn include cli-
toromegaly (clitoral length ≥9 mm), posterior labioscrotal fusion (anogenital
ratio >0.5), and single urogenital opening. Androgen exposure prior to 12 weeks
of intrauterine life results in clitoromegaly, single urogenital opening, and
posterior labioscrotal fusion, whereas exposure to androgens after 12 weeks of
intrauterine life results in isolated clitoromegaly (Fig. 9.4 ).Fig. 9.4 Features of
prenatal virilization in a
46,XX child. Note
clitoromegaly, posterior
labial fusion, and single
urogenital opening
- What are the causes of blind vaginal pouch?
Upper two-thirds of the vagina develops from Mullerian duct, whereas the lower
one-third from urogenital sinus. Blind vaginal pouch refers to the presence of
lower one-third of vagina with hypoplastic/absent Mullerian derivatives (uterus,
fallopian tubes, and upper two-thirds of vagina). The causes of blind vaginal pouch
in an individual with 46,XY DSD include complete androgen insensitivity syn-
drome, androgen biosynthetic defects (e.g., 17α-hydroxylase defi ciency,
17 β-hydroxysteroid dehydrogenase type 3 defi ciency), and 5α-reductase type 2
defi ciency. Presence of blind vaginal pouch in an individual with 46,XY DSD is
due to defective secretion/action of testosterone and preserved secretion of AMH
from the gonad. Preserved secretion of AMH results in regression of Mullerian
derivatives whereas impaired secretion/action of testosterone results in differentia-
tion of urogenital sinus into urethra and lower one-third of vagina (blind vaginal
pouch). In addition, blind vaginal pouch can also be present in individuals with
Mayer–Rokitansky–Kuster–Hauser syndrome and ovotesticular DSD (Fig. 9.5 ).9 Disorders of Sex Development