Ambiguous
Genitalia in the Newborn
Initial Assessment and Investigation
|
Reviewed by Carl Kuschel
and Wayne Cutfield (Paediatric Endocrinology) |
July
2003 |
The neonate presenting with ambiguous genitalia
should be treated as an emergency as underlying causes, such as Congenital
Adrenal Hyperplasia (CAH) can be life-threatening. In addition, determination of
gender is a primary concern for parents.
Aetiology
|
Virilised
Females |
Feminised
Males |
Congenital
Adrenal Hyperplasia
- 21-hydroxylase deficiency
- 11-hydroxylase deficiency
- 3β-hydroxylase deficiency
|
Congenital
Adrenal Hyperplasia
- 3β-hydroxylase deficiency
|
| Chromosomal
Abnormalities
|
Partial
Androgen Resistance Syndromes
- 5 α-reductase deficiency
- Partial androgen receptor defects
|
Maternal
Virilisation
- Drug-induced
- Excessive androgen production by
mother
|
Defect
in Testicular Development |
|
True Hermaphroditism |
True Hermaphroditism |
Idiopathic
- Isolated
- Associated with midline congenital
anomalies
|
Idiopathic
- Isolated
- Associated with midline congenital
anomalies
|
History
- Drug ingestion during pregnancy?
- Any recent androgenic changes in the mother
suggesting androgen excess?
- Are there few (or no) male offspring in families
on mother's side?
- Any siblings dying in the newborn period?
- Any siblings with over-virilisation or
precocious puberty?
- Any history of infection or exposure to
teratogens?
Physical Examination
Although physical examination is useful, a
diagnosis should not be made solely on examination findings. However, the
following information is useful in determining what investigations are required.
- Are gonads palpable?
- 25% of infants with
undescended testes
and hypospadias have an intersex disorder
- Gonads palpable in the perineum almost
always indicate a male karyotype
- Is the penile length normal?
- Measure stretched length with a spatula
from the symphysis pubis to the stretched tip (not foreskin) of the penis
- Normal stretched length >3cm at term
- <2.5cm at term indicates a microphallus
- Is there reasonable penile girth on
palpation?
- Is the phallus straight or is there
chordee present?
- Where is the urethral opening?
- How fused are the labioscrotal folds?
- Is the scrotum hypoplastic?
- Is the anus normally sited?
- Are there any other physical abnormalities?
Investigations
-
Chromosome analysis
-
Pelvic/abdominal ultrasound scan
to determine pelvic structures and the presence or absence of gonads.
Uterine tissue excludes the
presence of any testicular tissue in early gestation.
-
17-hydroxyprogesterone
(newborn screening card for urgent 17OHP)
-
Serum for Testosterone
-
Serum electrolytes and glucose
Management
- Be careful with discussions with parents.
Discuss with the specialist on call before discussing specifics with
parents.
- It is important to say that the baby has
"unfinished genitalia" rather than to talk about a penis or
clitoris.
- Parents should be advised not to name the
baby until the gender is known.
- Parents may choose to delay a birth notice
and may wish to restrict visitors until the gender has been assigned.
- Gender assignment is not dependent on what
structures are present alone, nor the karyotypic gender.
- Early referral to the Paediatric Endocrine Service
after initial clinical evaluation.
- Surgical service involvement will be at
the discretion of the Paediatric Endocrine Service.
- Specific investigations and management will depend on the
underlying cause.
