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- How to assess the posterior labial fusion?
Posterior labial fusion is objectively assessed by the measurement of anogenital
ratio, which is calculated by the distance between the anus and posterior four-
chette divided by distance between the anus and base of phallus. If the ratio is
>0.5, it suggests posterior labial fusion.- What is the fate of the urogenital sinus?
In a developing embryo, the primitive Wolffi an and Mullerian ducts are
attached to the cloaca. This is followed by differentiation of the cloaca into
the urogenital sinus anteriorly (along with Wolffi an and Mullerian ducts) and
rectum posteriorly. In females, regression of Wolffi an ducts occurs between 8
and 12 weeks; and the urogenital sinus starts differentiating into the lower
part of the urinary bladder, urethra, and lower one-third of the vagina by
8–9 weeks; and two distinct openings, urethral and vaginal opening, are
appreciable at perineum by 16–17 weeks. In males, regression of Mullerian
ducts occurs between 7 and 11 weeks, and the urogenital sinus develops into
the lower part of the urinary bladder, urethra, and prostate by 8–12 weeks
(Fig. 10.6 ).Prader Stage
Normal I II III IV V NormalFig. 10.5 Prader staging for virilization of external genitalia in a 46,XX newborn
10 Congenital Adrenal Hyperplasia