Diagnostic ultrasound ( PDFDrive )

1888 PART V Pediatric Sonography
Although feminizing adrenal tumors are a rare cause of
pseudoprecocious puberty, sonographic examination of the
adrenal areas should be performed in all patients with precocious
puberty who are referred for pelvic ultrasound. he liver should
be examined as well because precocious puberty has been associated
with hepatoblastoma. In isolated premature thelarche (breast
development) or premature adrenarche (pubic or axillary hair
development), sonography shows normal prepubertal uterus and
ovaries.
NORMAL MALE ANATOMY
The Prostate
he coniguration of the prostate is ellipsoid in boys compared
with the more conical shape seen in men. he prostatic echogenicity
is hypoechoic and more homogeneous than in the adult
prostate, which is frequently heterogeneous secondary to central
gland nodules, calciications, and corpora amylacea. 84,85 Prostate
volume may be calculated by using the formula for a prolate
ellipsoid (mentioned earlier for ovarian volume).
Ingram and colleagues 86 showed that in a group of 36 boys,
ages 7 months to 13.5 years (mean 7.7 years), the prostatic volume
ranged from 0.4 to 5.2 mL (mean 1.2 mL). he seminal vesicles
may be identiied in young boys and adolescents and are best
seen in the transverse plane as small, hypoechoic structures giving
an appearance similar to a bow tie or the wings of a seagull
(Fig. 54.27).
The Scrotum
Before sonographic examination of the scrotum, the clinician
should carefully palpate the entire scrotum. he pediatric scrotum
is examined with a high-frequency linear array broadband
transducer, generally a 12-5 MHz for children and teenagers and
a 17-5 MHz, small-footprint, “hockey stick” probe for very small
FIG. 54.27 Seminal Vesicles. Through a well-distended bladder (B),
the seminal vesicles (arrows) are seen as hypoechoic, bilaterally symmetrical
structures with a “bow tie” appearance.
testes in infants and young children and for atrophic testes. It
is helpful to elevate and immobilize the testes by gently placing
a rolled-up towel posterior to the scrotum between the legs. For
accurate measurements of larger adolescent testes, a curvilinear,
broad-bandwidth probe, either a 9-4 or 5-2 MHz, and a stepof
pad may be necessary. In infants or any patient with a painful
scrotum, a stepof pad is essential to perform this valuable study.
Both hemiscrota should be routinely examined so that diferences
in size and echogenicity of the intrascrotal contents can be
recognized. Color Doppler imaging parameters should be
optimized for the best detection of low-velocity and low-volume
blood low typically seen in the scrotum (color gain settings are
maximized until background noise becomes visible, and wall
ilter and pulse repetition frequencies are adjusted to the lowest
settings). Power Doppler imaging, with its increased sensitivity
for the detection of blood low, is useful for examination of slow
low states in the cooperative patient and particularly in very
young children who normally have low testicular low. In very
small testes, power output may need to be increased to detect
low. Color low in the two hemiscrota should be compared for
symmetry. he addition of pulsed Doppler imaging allows for
quantitative evaluation of arterial waveforms and measurements
of velocity.
The Testes
he normal newborn testes have a homogeneous low- to mediumlevel
echogenicity and are spherical or oval in shape with a length
of 7 to 10 mm (Fig. 54.28). he epididymis and mediastinum
testis are usually not seen in the neonate. By puberty, the testis
contains homogeneous medium-level echoes and an echogenic
linear structure along its superoinferior axis, which represents
the mediastinum testis (Fig. 54.29, Video 54.4). he testis measures
3 to 5 cm in length and 2 to 3 cm in depth and width ater
puberty. Studies of testicular sizes during infancy and adolescence
performed using orchidometers report the range of mean testicular
volumes as 1.10 mL (standard deviation [SD] ± 0.14) and 30.25 mL
(SD ± 9.64). 87 Normal testes smaller than 1 mL can be present
in young infants and children. 88,89 he tunica albuginea may be
seen as a thin echogenic line around the testis. Occasionally, a
hypoechoic linear band is noted in the normal testis, usually in
the middle third, corresponding to sites of intratesticular
vessels. 90
he normal color Doppler appearance of the testes changes
with age. Despite optimized slow-low settings, it may not be
possible to detect color low in normal, small, prepubertal
testes. 88,89,91 Atkinson and colleagues 88 reported that centripetal
arterial low could be identiied with color Doppler imaging in
only 6 (46%) of 13 testes measuring less than 1 mL and in all
testes measuring greater than 1 mL. When color low is seen in
prepubertal testes, it generally appears as pulsatile foci of color
without the linear or branching pattern seen in adolescents or
adults 88 (see Fig. 54.29). he recurrent rami arteries are usually
too small to be identiied in children, although they may be seen
in adolescents. Color Doppler can demonstrate low in 60% to
83% of prepubertal testes, and power Doppler imaging can
demonstrate low in 73% to 92% of prepubertal testes. Luker
and Siegel 91 showed that power mode Doppler ultrasound