Diagnostic ultrasound ( PDFDrive )

CHAPTER 54 Pediatric Pelvic Sonography 1881
tumors generally have central, low-resistance arterial Doppler
waveforms (resistive index [RI] < 0.4, or pulsatility index [PI]
< 1.0), thought to be caused by a relative paucity of a muscular
layer in the neoplastic vessels, 53 thereby limiting the speciicity
of Doppler imaging. 54 Benign ovarian masses tend to have
peripheral, high-resistance low (RI > .7 or PI > 1.0). However,
nonneoplastic lesions (e.g., tubo-ovarian abscess, ectopic pregnancy,
functioning corpus luteum) also have low-resistance low,
and some malignant tumors show high-resistance low.
UTERINE AND VAGINAL
ABNORMALITIES
Congenital Anomalies
Congenital anomalies of the uterus and vagina in children are
uncommon and usually manifest as an abdominal or pelvic mass
secondary to obstruction. here is a high incidence of associated
renal anomalies (50%) and an increased incidence of skeletal
anomalies (12%). 55 he uterus, cervix, and upper two-thirds of
the vagina are formed by the fused caudal ends of the müllerian
(paramesonephric) duct. he paired fallopian tubes are formed
by the unfused upper ends. he lower third of the vagina is
derived from the urogenital sinus. Müllerian duct development
into the uterus is dependent on the formation of the wolian
(mesonephric) duct. herefore abnormal development of the
müllerian duct, resulting in uterine and vaginal anomalies, is
oten associated with renal anomalies. 56,57
he bicornuate uterus is the most common congenital uterine
anomaly. It results when the two müllerian ducts fuse only
inferiorly 58 (Fig. 54.17). he two separate uterine horns, which
are joined at a variable level above the cervix, are best demonstrated
on transverse sonograms through the superior portion
of the uterus. Most oten only one cervix is visualized (when
FIG. 54.17 Bicornuate Uterus. Transverse image of the uterus in
a 20-year-old woman with acute lower abdominal and pelvic pain reveals
two separate endometrial cavities (arrows) in the middle to fundal region
of the uterus.
there are two, this is a bicornis bicollis) and one vagina is identiied.
With complete duplication of the müllerian ducts
(didelphys), there is a septated vagina and duplicated cervix
and uterus. In either anomaly, obstruction of one uterine horn
can result in a pelvic mass from unilateral hydrometra or
hematometra. Other septation anomalies of the uterus can result
from incomplete involution of the midline septum between the
paired müllerian ducts. A unicornuate uterus is formed from
the agenesis of one müllerian duct. 59 In utero exposure to
diethylstilbestrol (DES) has been associated with development
of a T-shaped uterus. Sonography shows a narrow uterus caused
by absence of the normal, superior, bulbous expansion of the
uterine fundus. hree-dimensional sonography is an excellent
modality for obtaining planar reformatted sections through the
uterus, which allows for precise evaluation of the anatomy. 57
Hydrocolpos or hydrometrocolpos, caused by obstruction
of the vagina, accounts for 15% of abdominal masses in newborn
girls (Fig. 54.18). he obstruction is secondary to an imperforate
hymen, a transverse vaginal septum, or a stenotic or atretic
vagina. here is an accumulation of mucous secretions proximal
to the obstruction. he secretions are secondary to intrauterine
and postnatal stimulation of uterine and cervical glands by
maternal estrogens. A simple imperforate hymen is not usually
associated with other congenital anomalies. However, there is a
high incidence of genitourinary, gastrointestinal, and skeletal
anomalies associated with vaginal atresia or a midtransverse
or high-transverse vaginal septum. Combined perinealabdominal
sonography is an excellent method for accurate
assessment of these anomalies. 60 Although TAS is useful to
determine if hydrocolpos or hydrometrocolpos is present, this
method does not allow measurement of the thickness of a caudally
placed obstructive septum. On sonographic examination,
hydrocolpos appears as a large, tubular, cystic mass posterior to
the bladder and extending inferior to the symphysis pubis. 61
Low-level echoes within the luid represent mucous secretions
in neonates and blood in postpubertal girls 62 (Fig. 54.19). here
may be secondary urinary retention and hydronephrosis.
Imperforate anus, cloacal exstrophy, and persistent urogenital
sinus oten have associated hydrometrocolpos. 63-65 Rarely, one
may see peritoneal calciications complicating hydrometrocolpos
because of a sterile inlammatory reaction to spillage into the
peritoneal cavity of accumulated secretions. 66
he Mayer-Rokitansky-Küster-Hauser syndrome, the second
most common cause of primary amenorrhea, comprises vaginal
atresia, rudimentary uterus, normal fallopian tubes and ovaries,
and broad and round ligaments. 55 he spectrum of uterine
anomalies (hypoplasia or duplication) ranges from a partial lumen
to a septate or bicornuate uterus with unilateral or bilateral
obstruction. hese girls have a normal female karyotype, secondary
sexual development, and external genitalia. here are high
incidences of unilateral renal (50%) and skeletal (12%) anomalies.
Unilateral renal agenesis and ectopia are the most common renal
anomalies. he most common sonographic indings are uterine
didelphys with unilateral hydrometrocolpos and ipsilateral renal
agenesis. Water vaginography can help identify the septated vagina
with unilateral vaginal obstruction 55 (Fig. 54.20). he analogous
genitourinary defects in the male result in duplicated müllerian