Dr. Hebert is a Radiology Resident at the University of North Carolina, Durham, NC, and Dr. Chong is Chief of Diagnostic Ultrasound and a Professor of Radiology at the University of North Carolina, Chapel Hill, NC. Dr. Deurdulian is Chief of Imaging Services, W. G. Hefner VA Medical Center, Salisbury, NC.
is the primary modality for imaging palpable testicular lesions in the
setting of acute traumatic injury/pain. Many scrotal ultrasounds are
performed every year for these common conditions. Accurate
interpretation of the findings is essential to guiding treatment and
further intervention because a wide spectrum of pathologies can produce
The scrotal ultrasound exam is
performed with the patient in the supine position and a rolled towel or
sheet placed between the legs to support the scrotum. The penis is
positioned superiorly or superolaterally and draped with a towel.
Scanning is usually performed with an 8-MHz to15-MHz transducer with
sequential sagittal and transverse images. Higher-frequency transducers
allow for greater resolution of the scrotal contents, but lower
frequency transducers can be employed for an edematous scrotum.
Transverse side-by-side images of both testes are obtained to compare
flow symmetry, echogenicity, and scrotal wall thickness. Color and power
Doppler ultrasound are also used to detect perfusion and verify
abnormal flow patterns.
testicle measures between 3 cm and 5 cm in length, 2 cm and 4 cm in
width, and approximately 3 cm in AP dimension. The tunica vaginalis
consists of visceral and parietal layers. The parietal layer lies
against the scrotal wall; the visceral layer envelops all but the
posterior portion of the testicle.1 The tunica albuginea
surrounds the testicle; however, this is not normally visible under
ultrasound unless fluid surrounds the testicle (Figure 1). The
epididymis is an elongated, crescent-shaped structure that measures
approximately 6-cm to 7-cm long and is usually isoechoic or hypoechoic
relative to the testicle. The epididymis is usually located along the
superior portion of the testicle, and the tail extends inferolaterally,
eventually continuing as the vas deferens (Figure 2). The rete testis is
formed by the convergence of seminiferous tubules within the
mediastinum of the testicle.2 The paired testicular arteries,
arising from the abdominal aorta, are the main blood supply to the
testes. They enter the scrotum through the inguinal canal. There is
collateral circulation from the deferential artery (a branch of the
inferior vesical artery, which arises from the internaliliac) and the
cremasteric artery (a branch of the inferior epigastric artery). The
testicular arteries, as well as the pampiniform plexus, nerves, and
lymphatics, converge within the spermatic cord and course toward the
tunica albuginea. Once the testicular artery enters the tunica
albuginea, it branches into capsular arteries and eventually into
recurrent rami branches that course centrifugally into the mediastinum.
The remaining portions of the scrotum receive arterial blood from the
pudendal arteries, which arise from the internal iliac artery. A
transmediastinal artery persists in ≤50% of patients and will appear as a
prominent hypoechoic band within the testicle, with blood flow in the
opposite direction of the recurrent rami arteries with Doppler imaging.3
anatomic relationships of the vasculature to the spermatic cord are
important because of several common conditions that can be related to
changes in the normal relationships. For example, the bell-and-clapper
deformity is a high insertion of the tunica vaginalis onto the spermatic
cord, which leaves the testes free to rotate within the tunica and can
predispose to intravaginal testicular torsion. Another anatomic
correlate is that testicular varicoceles occur more commonly on the left
side, likely because the left testicular vein drains via the left renal
vein into the inferior vena cava (IVC), rather than directly into the
IVC, as with the right testicular vein.3
of the rete testis is an idiopathic, benign condition that may be
associated with partial or complete obstruction of the efferent
ductules, leading to cystic dilatation. This condition occurs most
frequently in men older than 55 and is frequently bilateral, although
unilateral occurrences are also seen.4 The characteristic
finding of this lesion is a peripheral, elongated structure composed of
multiple small, cystic ortubular structures that replace the mediastinum
without causing significant mass effect.5 There are no calcifications, solid components, or flow on Doppler imaging (Figure 3).6
may be extratesticular or intratesticular. Of the extratesticular
varieties, the left-side ones are more frequently involved because their
venous drainage is indirect: The left testicular vein drains into the
left renal vein, while the right testicular vein drains directly into
the IVC. Vein diameter >3 mm and/or >1 mm of reflux during
Valsalva are diagnostic of a varicocele (Figure 4).7 Reported
infertility rates with varices are as high as 33%, although the size of
varices does not correlate with likelihood of infertility.3
simple cysts are common and have the usual ultrasound characteristics
of benign cysts. Cysts of the tunica are common after trauma and
frequently are palpable by the patient. They may show calcification on
ultrasound. Epidermoid cysts are also benign and account for1% to 2% of
all resected testicular masses.8 These lesions show
alternating rings of hyperechogenicity and hypoechogenicity on
ultrasound,leading to the characteristic “onion ring” sign (Figure 5).5 Typically,
epidermoid cysts show no flow on Doppler imaging, helping to
differentiate them from the majority of other solid intratesticular
Tunical fibromas are benign, painless tumors
that arise most frequently from the tunica vaginalis, but they can arise
from the tunica albuginea, the spermatic cord, or even the testicular
parenchyma in rare cases. On ultrasound, these lesions are usually
well-defined hyperechoicmasses measuring 1 cm to 3 cm in diameter
centered on the tunica, although they rarely can appear poorly defined
and hypoechoic. Posterior acoustic shadowing often signifies a dominant
Sperm granulomas result from a
chronic inflammatory process against extravasated sperm from damage to
the tubules, usually in a patient with history of trauma, infection, or
surgery. These lesions are frequently solid, well-defined, and
hypoechoic extratesticular masses measuring ≤1 cm. They are usually
found within the epididymis or along the course of the vas deferens.9
tumors are the most common epididymal tumors; they comprise about 30%
of paratesticular neoplasms. They are frequently well defined and can
range from 3 mm to 5 cm in size. The lesion will show an echotexture
similar to, or slightly greater than, the testis without increased flow
on Doppler imaging (Figure 6).9
most commonly presents with an enlarged, hypoechoic epididymis with or
without calcifications. Testicular involvement can occur from epididymal
extension and result in an enlarged hypoechoic testicle, sometimes with
a nodular appearance. The appearance is often nonspecific, but the
presence of bilateral epididymal involvement or heterogeneous hypoechoic
epididymal enlargement with a testicular lesion favors tuberculosis
over other infections.9
Scrotal sarcoid is a rare
complication of sarcoidosis, but epididymal and testicular involvement
do occur. On ultrasound, single or multiple hypoechoic masses or a
solitary echogenic mass involving the epididymis or testis can appear.9
is rare and can range from testicular duplication alone to duplication
of the epididymis or the spermatic cord. These duplications are thought
to be due to abnormal division of the embryonic genital ridge. On
ultrasound, duplicated testicles can be recognized by their resemblance
to a normal testis; they will have a mediastinum testis. The patients
have an increased risk of cryptorchidism, inguinal hernia, and
Congenital adrenal hyperplasia
(CAH) refers to a group of inherited disorders that cause defects in
the adrenal glands’ ability to produce cortisol from cholesterol,
leading to increased levels of adrenocorticotropic hormone (ACTH). In
patients with CAH, ectopic adrenal rest tissue is frequently identified
within the testicles. In response to elevated levels of ACTH, this rest
tissue enlarges and can present as a palpable mass.10 On
ultrasound, these lesions are typically bilateral, hypoechoic,
predominantly located peripherally, and show minimal mass effect (Figure
7).11 Additionally, a spoke-like pattern of vascularity may
be present within the mass on color Doppler, but many of the masses will
appear hypovascular or avascular.11
microlithiasis is defined as >5 punctate, nonshadowing,
intratesticular calcifications (Figure 8). Although there is an
association between microlithiasis and testicular cancer, microlithiasis
is very common – the prevalence is 5.6% (14.1% of African
Americans).Longitudinal studies have shown that very few patients with
microlithiasis will develop testicular cancer.12 Consequently, surveillance ultrasound for patients with microlithiasis is impractical and no longer recommended.
malignancy is the most common cancer in young men. Ultrasound’s
sensitivity to testicular neoplasms is reported to be between 87.5% and
100%, with specificities between 55% and 66.7%.13 The
overwhelming majority of primary testicular cancers are germ cell
tumors. The commonest germ cell tumors are seminomas, mixed germ cell
tumors, and teratomas. The ultrasound appearance of seminomas is usually
a solid, hypoechoic mass; however, they can appear heterogeneous with
microlithiasis or necrosis (Figure 9).14 Twenty-five percent of patients will have distant spread of the disease via lymphatic or hematogenous routes.14 The
primary tumor may outgrow its blood supply and involute in patients
with systemic metastases. In this situation, known as the “burnt out”
tumor, the primary lesion appears disproportionately small. Ultrasound
examination may show a nonspecific hypoechoic or hyperechoic testicular
lesion, which may be calcified, in the presence of large, systemic
Nonseminomatous germ cell tumors are the most common
testicular cancer, usually presenting in patients <30 years old. In
general, they are more aggressive than seminomas. On ultrasound imaging,
they are often heterogeneous, and they can show areas of necrosis,
hemorrhage, or calcification.14
Lymphoma is the most
common secondary tumor of the testes. It most commonly occurs in
patients >60 years, with non-Hodgkin’slymphoma being the most
frequent. It may appear on ultrasound as a diffuse, hypoechoic
enlargement of the testis or as an avascular, hypoechoic, and
intratesticular mass (Figure 10).14
involvement is also common, as the blood-gonad barrier shields the
testis from systemic chemotherapy. The ultrasound appearance often shows
diffusely enlarged, hypoechoic testicles, frequently indistinguishable
Acute scrotal pain
is essential to the evaluation of acute scrotal pain, but the exam must
be correlated with clinical findings. Ultrasound is excellent at
differentiating surgical causes from medical causes of testicular pain.15
trauma is usually related to blunt force, with athletic injuries being
the most frequent cause. The right side is more likely tobe injured due
to trapping of the testicle against the pubis. Ultrasound is used to
evaluate the integrity of the tunica and the testicular blood supply.
Testicular rupture is defined as disruption of the tunica albuginea and
requires surgical exploration. Ultrasound findings include irregular
testicular contour and decreased or absent vascularity (Figure 11).
Recognition of these findings is important because surgery within 72
hours of the injury results in testicular salvage in approximately 80%
of cases.16 Testicular fracture without disruption of the
tunica albuginea can be managed conservatively if perfusion is preserved
(Figure 12). The integrity of the testicular blood supply can be
confirmed with Doppler imaging.2 Either injury can result in hematoceles that eventually transform into post-traumatichydroceles.
torsion and epididymo-orchitis are the most common causes of
nontraumatic testicular pain. Differentiating between them can be
clinically difficult. Color Doppler ultrasound is highly sensitive and
specific (85%-100%) in torsion. As with rupture,early diagnosis is
critical. The rate of successful testicular salvage is between 80% and
100% within 6 hours of symptom onset, butit decreases to 20% after 12
hours.14 On Doppler ultrasound the blood flow within the
symptomatic testicle will be decreased or absent(Figure 13). Grayscale
appearance of the testicle may be normal at this point. Grayscale
abnormalities, such as heterogeneous echo texture, occur late and
usually reflect a testicle that is no longer viable.17 Care
must be taken to perform the ultrasound with low-pulse repetition
frequency and high Doppler gain to effectively demonstrate the slow flow
inherent to testicular vessels.14 Because the findings can
sometimes be subtle, obtaining side-by-side comparison images of both
testicles with grayscale and spectral Doppler imaging to assess for
symmetry is very important. The presence of blood flow documented with
color Doppler imaging alone cannot completely exclude torsion. In
partial torsion or torsion/detorsion, flow can be present while the exam
is performed; sometimes, compensatory hyperemia is actually present.3 In
partial torsion, flow may be present on color Doppler, but spectral
imaging can show high resistance waveforms within the testicular artery.
of the appendix testis occurs less frequently than testicular torsion.
Ultrasound will show a hyperechoic avascular mass adjacent to the testis
or epididymis. Blood flow within the testicle will be normal (Figure
14). Torsion of the appendix testis is self-limiting and does not
require surgical intervention.3 Segmental testicular
infarction is also a rare complication, usually following surgery for
primary inguinal hernia repair, although the risk increases up to as
much as 5% in patients undergoing repair of recurrent hernia.18
epididymo-orchitis will show increased blood flow within both the
testicle and the epididymis, often with an enlarged, hypoechoic testicle
and epididymis on the symptomatic side (Figure 15).14 Again,
obtaining side-by-side comparison images of both testicles is very
important for accurate evaluation. Patients presenting in the advanced
stages of epididymo-orchitis may show decreased flow due to ischemic
changes.Complications from epididymo-orchitis include abscess formation
with complex hydrocele or testicular ischemia due to epididymal edema
compressing the testicular venous outflow.19 Fournier
gangrene is a necrotizing infection that involves the soft tissues of
the male genitalia.Findings include a thickened, edematous scrotal wall
with gas, seen as hyperechoic linear foci with reverberation artifacts.
Gas may be seen on ultrasound prior to the finding of crepitus on
clinical examination (Figure 16). Reactive hydroceles can also be
present, but the testes and epididymides often appear normal due to
separate blood supplies.20 Differentiate Fournier’s from
epididymo-orchitis is critical because Fournier’s requires surgical
debridement and more aggressive antibiotic therapy.
is the preferred imaging modality for the scrotum because of its low
cost, lack of ionizing radiation, and ability to image in real time. The
clinical history and examination of patients presenting with scrotal
symptoms frequently overlap among multiple etiologies, and a thorough
understanding of the usual findings to aid in differentiating surgical
from medical, and benign from malignant, etiologies is required to
accurately guide patient care.
- Garriga V, Serrano A, Marin A, et al. US of the tunica vaginalis testis: Anatomic relationships and pathologic conditions. Radiographics. 2009;29:2017-2032.
Deurdulian C, Mittelstaedt C, Chong WK, Fielding JR. US of acute
scrotal trauma: Optimal technique, imaging findings, and management. Radiographics. 2007;27:357-369.
- Chen P, John S. Ultrasound of the acute scrotum. Applied Radiology. 2006;35:8-17.
- Tartar MV, Trambert MA, Balsara ZN, Mattrey RF. Tubular ectasia of the testicle: Sonographic and MR imaging appearance. AJR Am J Roentgenol. 1993;160:539-542.
- Dogra VS, Gottlieb RH, Rubens DJ, Liao L. Benign intratesticular cystic lesions: US features. Radiographics. 2001;21:S273-S281.
- Kenny D, Batra K, Nancy M, et al. Radiological case: Tubular ectasia of rete testis with spermatocele. Applied Radiology. 2008;37:38-39.
- Dudea SM, Ciurea A, Chiorean A, Botar-Jid C. Doppler applications in testicular and scrotal disease. Med Ultrason. 2010;12:43-51.
- Langer JE, Ramchandani P, Siegelman ES, Banner MP. Epidermoid cysts of the testicle: Sonographic and MR imaging features. AJR Am J Roentgenol. 1999;173:1295-1299.
- Deurdulian C, Chong WK, Mittlestaedt CA, et al. Unusual scrotal masses: Thinking beyond germ cell tumors. Poster.
- Maizlin ZV, Strauss S. Testicular adrenal rest tumors. Isr Med Assoc J. 2005;7:206-207.
Avila NA, Premkumar A, Merke DP. Testicular adrenal rest tissue in
congential adrenal hyperplasia: Comparison of MR imaging and sonographic
findings. AJR Am J Roentgenol. 1999;172: 1003-1006.
- Costabile RA. How worrisome is testicular microlithiasis? Curr Opin Urol. 2007;17:419-423.
Rizvi SA, Ahamd I, Siddiqui MA, et al. Role of color Doppler
ultrasonography in evaluation of scrotal swellings: Pattern of disease
in 120 patients with review of literature. J Urology. 2011;8:60-65.
Cokkinos DD, Antypa E, Tserotas P, et al. Emergency ultrasound of the
scrotum: A review of the commonest pathologic conditions. Curr Probl Diagn Radiology. 2011;40: 1-14.
Guichard G, El Ammari J, Del Coro C, et al. Accuracy of ultrasonography
in diagnosis of testicular rupture after blunt scrotal trauma. Urology. 2008;71:52-56.
- Bhatt S, Dogra VS. Testicular and scrotal trauma. Radiographics. 2008;28:1617-1629.
Kaye JD, Shapiro EY, Levitt SB, et al. Parenchymal echotexture predicts
testicular salvage after torsion: Potential impact on the need for
emergent exploration. J Urology. 2008; 180(Suppl):1733-1736.
Holloway BJ, Belcher HE, Letourneau JG, Kunberger LE. Scrotal
sonography: A valuable tool in the evaluation of complications following
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- Horstman WG, Middleton WD, Melson GL, Siegel BA. Color Doppler US of the scrotum. Radiographics. 1991;11:941-957.
- Levenson RB, Singh AK, Novelline RA. Fournier gangrene: Role of imaging. Radiographics. 2008;28:519-528.