Ambiguous Genitalia - Paediatrics

Ambiguous Genitalia

·        Relative complexity of male differentiation ® vulnerable to wide variety of incomplete masculinisation

·        History and exam:

o   Exposure to progesterone, testosterone, phenytoin, aminoglutethamide

o   Previous neonatal deaths

o   Phallic size, position of urethral orifice, fused labia, descended gonads

·        Don‟t rely on appearances whenever babies have:

o   Bilateral cryptorchidism, even if there is a phallus

o   Unilateral cryptorchidism with hypospadias

o   Peno-scrotal or perineoscrotal hypospadius

·        Causes:

o   Androgen resistance (extreme form: testicular feminisation) 

§  Early in boys development, sertoli cells release anti-mullerian peptide ® stops formation of the fallopian tubes, uterus and the upper 1/3 of the vagina 

§  Testosterone and dihydrotestosterone from Leydig cells responsible for the rest of male genitalia. If a problem in this pathway ® Girl with short vagina.

§  Present in puberty with primary amenorrhoea

o   Adrenogenital Syndrome:

§  Incidence: 1 in 14,000

§  Congenital adrenal hyperplasia: masculinsed females 

§  ­Androgenic hormones because of ¯ 21-hydroxylase, 11-hydroxylase or 3-B-hydroxysteroid dehydrogenase 

§  Can‟t produce cortisol ® adrenal hyperplasia ® overproduction of cortisol precursors ® ­androgens 

§  Presentation: vomiting, dehydration and ambiguous genitalia. Hyponatraemia (with paradoxically high urine Na) and hyperkalaemia is common ® may present with circulatory collapse in early life or hyponatraemic seizures (misdiagnosed as febrile convulsions) 

§  Boys may present with precious puberty or have ambiguous genitalia (reduced androgens in 17-hydroxylase deficiency)