Diagnostic ultrasound ( PDFDrive )

CHAPTER 22 The Scrotum 821
A
B
FIG. 22.3 Spectral Doppler of Normal Intratesticular and Extratesticular Arterial Flow. (A) Intratesticular artery has a low-impedance
waveform with large amount of end diastolic low. (B) Extratesticular scrotal arterial supply (cremasteric and deferential arteries) has high-impedance
waveform with reversed low in diastole.
other appendages, such as the paradidymis (organ of Giraldés)
and the superior and inferior vas aberrans of Haller, may be
seen. 10 he appendages of the epididymis are most oten identiied
sonographically as separate structures when a hydrocele
is present.
Knowledge of the arterial supply of the testis is important for
interpretation of color low Doppler sonography of the testis.
Testicular blood low is supplied primarily by the testicular,
deferential, and cremasteric (external spermatic) arteries. he
testicular arteries arise from the anterior aspect of the aorta
immediately below the origin of the renal arteries. hey course
through the inguinal canal with the spermatic cord to the
posterosuperior aspect of the testis. On reaching the testis, the
testicular artery divides into branches that pierce the tunica
albuginea where the capsular arteries form and arborize over
the surface of the testis in a layer known as the tunica vasculosa,
deep to the tunica albuginea. Centripetal branches arise from
these capsular arteries; these branches course along the septa to
converge on the mediastinum. From the mediastinum, these
branches form recurrent rami that course into the testicular
parenchyma, where they branch into arterioles and capillaries 11
(Fig. 22.2G). In about 50% of normal testes a transmediastinal
artery supplies the testis, entering through the mediastinum
and coursing toward the periphery of the gland to supply the
capsular arteries, and is accompanied by a large vein, frequently
seen as a hypoechoic band in the midtestis 11,12 (Fig. 22.2H and
I). he transmediastinal artery may be associated with acoustic
shadowing obscuring the distal aspect of the testis and giving
rise to the “two-tone” testis appearance. 13 he deferential artery
originates from the superior vesical artery and courses to the
tail of the epididymis, where it divides and forms a capillary
network. he cremasteric artery arises from the inferior epigastric
artery. It courses with the remainder of the structures of the
spermatic cord through the inguinal ring, continuing to the
surface of the tunica vaginalis, where it anastomoses with capillaries
of the testicular and deferential arteries.
he velocity waveforms of the normal capsular and intratesticular
arteries show high levels of antegrade diastolic low
throughout the cardiac cycle, relecting the low vascular resistance
of the testis (Fig. 22.3A). Supratesticular arterial waveforms vary
in appearance. Two main types of waveforms exist: a low-resistance
waveform similar to that seen in the capsular and intratesticular
arteries, relecting the testicular artery; and a high-resistance
waveform with sharp, narrow systolic peaks and little or no
diastolic low 14 (Fig. 22.3B). his high-resistance waveform is
believed to relect the high vascular resistance of the extratesticular
tissues. he deferential and cremasteric arteries within the
spermatic cord primarily supply the epididymis and extratesticular
tissues, but they also supply the testis through anastomoses
with the testicular artery.
he spermatic cord consists of the vas deferens; the testicular,
cremasteric, and deferential arteries; a pampiniform plexus of
veins; the lymphatics; and the nerves of the testis. It courses
superiorly toward the supericial and deep (also called “internal”)
inguinal rings. Sonographically, the normal spermatic cord lies
just beneath the skin and may be diicult to distinguish from