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The Role of Ultrasound in the Evaluation of
Ambiguous Genitalia in the Newborn Linda S.
Woolpert, RT(R), RDMS and Joseph J. Junewick, MD
Introduction
The Feminized
Male Cloacal
anomalies
In general, phenotypic sex is determined by
the gonads which in turn are determined by the
chromosomes. The external genitalia of both
sexes are identical during the first 7 weeks of
gestation. Ambiguous genitalia represent a
segment of disorders of gender development where
the external genitalia are not clearly male or
female. Diagnostic evaluation of a newborn
with ambiguous genitalia should include physical
examination, karyotype with X- and Y-specific
probes, retroperitoneal and pelvic sonography,
hormone assays (17-hydroxyprogesterone,
testosterone, gonadotropins, anti-Mullerian
hormone), electrolyte panel and urinalysis.
The impact of imaging is most significant in
three distinct situations 1) the virilized
female and 2) the feminized male, and 3) cloacal
anomalies. The ultrasound imaging features of
these patients will be discussed in the context
of the chromosomal, gonadal/hormonal and
embryological dysfunction.
The feminized male is often referred to a male
pseudohermaphrodite. These patients have a
normal male karyotype, 46 XY. Typical female
external genitalia are present. There are many
etiologies for the male pseudohermaphrodite,
including androgen insensitivity, deficient
testosterone production, and 5-alpha-reductase
deficiency. Androgen insensitivity accounts for
the majority of male pseudohermaphrodites. This
x-linked defect results in the inability of the
receptor to bind dihydroxytestosterone or
inability of appropriate receptor mediated
cellular response and consequently failure of
normal male differentiation of the external
genitalia and prostate gland. External genitalia
are clearly female. Androgen deficiency is
related to enzymatic interruption of testosterone
biosynthesis or Leydig cell dysfunction.
Androgen deficient ambiguity responds to
exogenous testosterone treatment. Since
production of androgens share several
biosynthetic steps with congenital adrenal
hyperplasia, steroid and mineralcorticoid
replacement may also be necessary.
5-alpha-reductase deficiency patients have
minimally virilized external genitalia.
Diagnosis is made by high serum testosterone to
dihydroxytestosterone ratios in infancy.
Pelvic ultrasound may demonstrate mullerian
structures. Inguinal hernias are common in
androgen insensitivity and may contain a
testicle otherwise the testicles may be in the
retroperitoneum or labia. Adrenal glands are
usually normal.
Cloacal anomalies occur exclusively in females
with an incidence of 1 in 20,000 live births. The
external genitalia demonstrate typical female
features but are hypoplastic. Additional
ambiguity arises as a result of the single
perineal orifice. The cloaca is the embryologic
termination of the hindgut. The urorectal septum
forms and divides the cloaca into the anterior
urogenital sinus and the posterior anorectal
canal. The urogenital fold eventually divides
the urogenital sinus into the vagina and urethra.

A persistent cloaca is a common cavity formed by
the confluence of the genitourinary and
alimentary tracts. Urine flows into the cloaca
and backs up into the vagina. The distended
vagina displaces the bladder anteriorly and
results in hydronephrosis. Obstructive uropathy
is present in 90 of patients. The vagina must
be decompressed to avoid renal damage metabolic
perturbation, sepsis and even death may occur
without appropriate intervention. Hydrocolpos
with hypoplastic external genitalia should allow
for the correct diagnosis of persistent cloaca.
On sonography, hydrocolopos appears as a
pear-shaped fluid collection, often with debris
and a sediment-fluid level, with the uterus
superior. Differentiating a cystic pelvic mass
from the urinary bladder can be difficult. The
urinary bladder should be the most anterior
structure in the pelvis. Placement of a catheter
with infusion of a small amount of saline can be
helpful to characterize anatomy.
The Virilized Female
The virilized female is often referred to as a
female pseudohermaphrodite. These patients have
a normal female karyotype, 46 XX. The external
genitalia vary from mild clitoral enlargement to
a normal male phallus with an empty scrotum.
Congenital adrenal hyper- plasia (CAH) and
maternal exposure to androgens may result in a
virilized female. CAH is related to enzymatic
defect of either 21 hydroxylase, 11-hydroxylase,
or 3-beta-hydroxysteroid dehydrogenas. CAH is
the most common cause of ambiguous genitalia,
accounting for approximately 60 of cases.
Females always show varying degrees of
virilization. Males with CAH are phenotypically
normal ambiguity does occur with
3-beta-hydroxysteroid dehydrogenase since
testosterone production is affected.
Labioscrotal folds may be hyperpigmented
secondary to increased adrenocorticotropin
hormone levels. Adrenal gland enlargement is
characteristic of CAH occasionally adrenal
glands may demonstrate cerebriform undulations.
A normal adrenal gland should not measure greater
than 30 mm in length or 4 mm in width. Mullerian
structures (fallopian tubes and uterus) and
ovaries should be present and identified. Figure
1.
A
B
A
B
D
C
C
D
B
A
Figure 2. Newborn chromosomal male with
penoscrotal hypospadius. Pelvic ultrasound
reveals uterine development (A and B) and
undescended testicles (C and D).
A
B
D
C
Figure 4. Newborn admitted with single perineal
orifice, hypoplastic labia , hydronephrosis and
megacystis. Initial ultrasound confirms
hydronephrosis (A) and probable megacystis (B).
However on close evaluation, the urinary bladder
is displaced anteriorly by a cystic mass (C)
which is subsequently shown to represent
hydrometrocolpos (D).
Conclusions
Ultrasound plays an integral role in the
assessment of a newborn with ambiguous genitalia.
Evaluation of the adrenal glands,
retroperitoneum and labia for gonads, and pelvis
for mullerian structures will provide clinicians
with vital information for diagnosis and
treatment.
Figure 1. Two month old chromosomal female with
marked clitoromegaly. The left adrenal gland is
nearly as large as the kidney and demonstrates
convolutions resembling the cerebrum (A and B).
Images of the pelvis reveal a normal uterus
and no adnexal mass (C and D).
Figure 3. Newborn chromosomal male. Ultrasound
shows absence of gonads in the morphologic
labia (A). Uterine development is also noted
(B).
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