Ambitious genitalia

Question 1

basic physiology of ambiguous genitalia

Answer 1

Basic physiology
initially gonads in fetus are undifferentiated
on the Y chromosome there is a sex-determining gene (SRY gene) which causes differentiation of the gonad into a testis
if absent (i.e. in a female) then the gonads differentiate to become ovaries

Question 2

causes of of ambiguous genitalia and what is most common

Answer 2

Most common cause in newborns is congenital adrenal hyperplasia.
Other causes include:
true hermaphroditism
maternal ingestion of androgens

Question 3

summarise

Answer 3

Ambiguous genitalia

Basic physiology
initially gonads in fetus are undifferentiated
on the Y chromosome there is a sex-determining gene (SRY gene) which causes differentiation of the gonad into a testis
if absent (i.e. in a female) then the gonads differentiate to become ovaries

Most common cause in newborns is congenital adrenal hyperplasia. Other causes include:
true hermaphroditism
maternal ingestion of androgens

Question 4

You are performing a newborn baby check and discover during your examination that the neonate has ambiguous genitalia. On discussing this with the baby’s parents, they understandably distressed and want to know what the reason for this is.

What is the most likely cause of the ambiguous genitalia in this case?

Kallman’s syndrome
Androgen insensitivity syndrome
Male pseudohermaphroditism
Congenital adrenal hyperplasia
Cryptorchidism

Answer 4

Congenital adrenal hyperplasia

Ambiguous genetalia - congenital adrenal hyperplasia is most common cause in newborns

Congenital adrenal hyperplasia is the likely cause of ambiguous genitalia.

Individuals with Kallman’s syndrome do not have ambiguous genitalia, they are phenotypically and genotypically male, but have hypogonadotrophic hypogonadism. This is often diagnosed at puberty.

Androgen insensitivity syndrome is a condition in which the individual is phenotypically female, they do not have ambiguous genitalia.

Male pseudohermaphroditism is a cause of ambiguous genitalia, but a rare one, external genitalia are female or ambiguous and testes usually present.

Cryptorchidism is undescended testes. It is common at birth, occurring in 1-5% of newborns, but the genitalia is not ambiguous.