Diagnostic ultrasound ( PDFDrive )

CHAPTER 22 The Scrotum 819
Scrotal Sonography: Current Uses
Evaluation of location and characteristics of scrotal masses
Evaluation of acute scrotal pain
Evaluation of scrotal trauma, including surgical or iatrogenic
injury
Evaluation for varicoceles in infertile men
Evaluation of testicular ischemia with color and power
Doppler sonography
Follow-up of patients with previous testicular neoplasms,
lymphoma, or leukemia
Detection of occult primary tumor in patients with known
metastatic disease
Localization of the undescended testis
Efferent ductules
Septa
Seminiferous
tubules
Testicular artery
Pampiniform plexus
Head of epididymis
Spermatic cord
Cremasteric
artery
Vas deferens
Deferential
artery
Rete testes
size and appearance of each testis and epididymis should be
noted and compared to the contralateral structures. Color and
pulsed Doppler parameters should be optimized to evaluate for
low low velocities and to demonstrate blood low in the testes
and surrounding structures. Transverse images including portions
of both testes should be acquired in gray-scale and color Doppler
modes to demonstrate symmetry. Scrotal structures should be
examined thoroughly to evaluate for extratesticular masses or
processes. Additional techniques, such as upright positioning of
the patient or performing the Valsalva maneuver, may be used
to evaluate venous vascularity for varicocele or for inguinal hernia
assessment.
NORMAL ANATOMY
he normal scrotal wall consists of the epidermis, supericial
dartos muscle, dartos fascia, external spermatic fascia, cremasteric
muscle and fascia, and internal spermatic fascia. he scrotum
is a ibromuscular sac that is divided by the midline raphe, forming
a right and let hemiscrotum. Each hemiscrotum contains a testis,
epididymis, spermatic cord, and vascular and lymphatic networks
(Fig. 22.1).
he two layers of the tunica vaginalis separate the testis from
much of the scrotal wall and form an isolated mesothelial lined
sac. 1,2 During embryologic development, the tunica vaginalis
arises from the processus vaginalis, an outpouching of fetal
peritoneum that accompanies the testis in its descent into the
scrotum. he upper portion of the processus vaginalis, extending
from the internal inguinal ring to the upper pole of the testis,
is normally obliterated. he lower portion, the tunica vaginalis,
remains as a closed pouch within each hemiscrotum, partially
folded around the testis. Only the posterior aspect of the testis,
the site of attachment of the testis and epididymis, is not in
continuity with the tunica vaginalis.
he inner or visceral layer of the tunica vaginalis covers the
testis, epididymis, and lower portion of the spermatic cord. he
outer or parietal layer of the tunica vaginalis lines the walls of
the scrotal pouch and is attached to the fascial coverings of the
testis. A small amount of luid is normally present between these
two layers. 3
Tunica albuginea
Tunica vaginalis
Tail of
epididymis
Body of
epididymis
FIG. 22.1 Normal Intrascrotal Anatomy. (With permission from
Sudakoff GS, Quiroz F, Karcaaltincaba M, Foley WD. Scrotal ultrasonography
with emphasis on the extratesticular space: anatomy, embryology,
and pathology. Ultrasound Q. 2002;18[4]:255-273. 78 )
he ibrous tunica albuginea covers and protects the testis.
Posteromedially, the tunica albuginea projects inward into the
testis to form the mediastinum. Numerous ibrous septations
project inward from the mediastinum, dividing the testis into
250 to 400 lobules. Each lobule consists of one to three seminiferous
tubules supporting the Sertoli cells and spermatocytes. he
Leydig cells are adjacent to the tubules, within the loose interstitial
tissue, and are responsible for testosterone secretion.
he adult testes are ovoid glands measuring 3 to 5 cm in
length, 2 to 4 cm in width, and 3 cm in anteroposterior dimension.
Testicular size and weight decrease with age. 3,4 Sonographically,
the normal testis has relatively homogeneous, medium-level,
granular echotexture (Fig. 22.2A). Prepubertal testes are typically
less echogenic than postpubertal testes secondary to incomplete
maturation of the germ cell elements and tubules. 5 he tunica
(tunica vaginalis and tunica albuginea) can oten be seen as
an echogenic outline of the testes. Where the tunica invaginates
to form the mediastinum testis, the mediastinum testis is
sometimes seen as a linear echogenic band extending craniocaudally
within the testis (Fig. 22.2C). Its appearance varies
according to the amount of ibrous and fatty tissue present. he
ibrous septum, or septula testis, may be seen as a linear echogenic
or hypoechoic structure (Fig. 22.2B).
he seminiferous tubules converge to form larger tubuli
recti, which open into the dilated spaces of the rete testis. he
normal rete testis can be identiied in 20% of patients as a
hypoechoic region near the mediastinum. 6 he rete testis drains
into the epididymal head via 15 to 20 eferent ductules.
he epididymis is a curved structure measuring 6 to 7 cm
in length and lying posterolateral to the testis. It is composed