Diagnostic ultrasound ( PDFDrive )

1368 PART IV Obstetric and Fetal Sonography
A
B
C
FIG. 39.43 Ambiguous Genitalia. (A) Transverse view
and (B) three-dimensional image of the perineum in a
25-week fetus show ambiguous genitalia: a bulbous
structure (arrow) located between the two labial-like swellings.
(C) Postnatal photograph of the newborn at term
(chromosome sex XY) shows the penis with a chordee
and thus is severely incurved between the biid and asymmetrical
scrotum. There is also penoscrotal hypospadias
and right cryptorchidism.
absence of a family history, the ultrasound indings of enlarged
fetal adrenal glands and ambiguous genitalia are suggestive of
CAH. 260,261 Prenatal maternal administration of dexamethasone
can prevent or reduce virilization in afected female fetuses, but
it must be initiated on or before the ninth week of pregnancy
(before prenatal diagnosis of CAH can be made currently). 259
Because the ofspring of carrier parents have a 1 in 4 chance of
having CAH, and therefore only 1 in 8 will be a CAH-afected
female, mothers who want to undergo prenatal dexamethasone
treatment will be unnecessarily treating seven of eight fetuses,
who would be exposed to the risks of several weeks of steroid
therapy. A systematic review of the safety of prenatal steroid
therapy in CAH concluded that the available literature is uncertain
and inconclusive regarding the beneits or harms of dexamethasone
use in this setting, and this medication should be prescribed
only ater the parents have received detailed and informed
counseling. 262-264
Prenatal diagnosis of female pseudohermaphroditism with
bilateral luteoma of pregnancy has been reported. 265 In a genetic
male with female external genitalia, testicular feminization is
likely. Intersex states may be divided into hormonally and
nonhormonally mediated abnormalities. he latter oten have
associated cloacal anomalies or chromosomal aberrations or may
conform to one of numerous multimalformation syndromes. In
many cases, an accurate diagnosis and inal gender assignment
can be made only postnatally.
Hydrocolpos
Hydrocolpos is dilation of the vagina caused by luid accumulation.
It is associated with uterine dilation in hydrometrocolpos.
It occurs as a result of vaginal hypoplasia or agenesis, transverse
septum, or imperforate hymen. Hydrocolpos appears as a midline
pelvic mass, posterior to the bladder. It is generally anechoic
but may contain echogenic luid with a luid-debris level. When
associated with müllerian duct anomalies, it may appear as a
septate mass. 266 he enlarged vagina and uterus may compress
the UT and cause hydronephrosis or hydroureter. Hydrocolpos
may be associated with a wide spectrum of urorectal septum
malformations. herefore a detailed sonographic examination
including identiication of a normal anal canal and rectum
provides important information for prenatal counseling. 267 MRI
may be useful as an adjunct to ultrasound when pelvic anatomy
is not well identiied or to aid in diagnosis of cloacal malformation
or other associated GI abnormalities. 213,267,268