Sonography of
Scrotum and
Testes
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Anatomy
The scrotum is divided by the midline raphe. Each half of the
scrotum contains a spermatic cord, testis, and epididymis. The
testes descend into the scrotum at approximately the 28th
gestational week via the inguinal canal through the peritoneal
recess, which is called the processus vaginalis. The processus
vaginalis gradually closes through infancy and childhood. The testis
is covered by a visceral layer of tunica vaginalis, except where in
contact with epididymis, and by the tunica albuginea. The posterior
surface of the tunica albuginea extends into the testis to form the
mediastinum testis. This is seen as a middle echogenic line on
longitudinal US of the testis The testis has lobules containing the
seminiferous tubules. Testicular lobules are occasionally identified
as lines radiating from the mediastinum testis
•The size and shape of the testes change with age.
Testicular size is influenced by gonadal hormones. In boys,
from birth to 5 months of age, the testicular volume rises
to a maximum of 0.44 (±0.03) cm3. The rise in testicular
volume coincides with a peak in gonadotropic hormones,
so-called minipuberty, at approximately 3 to 4 months of
age.
After age 5 months, the testicular volume steadily
declines and reaches its minimum volume at
approximately 9 months of age and remains
approximately the same size until puberty.
The testis is rounded in newborns and gradually becomes
ovoid with growth.
•The epididymis has three parts: head, body, and tail. In
the normal epididymis, only the head is routinely
identified. The epididymal head is located in the upper
pole of the scrotum, is triangular in shape, and has the
same echogenicity as the testis.
•Testicular appendixes are remnants of the mesonephric
and paramesonephric ducts. They can be identified by
US in cases of hydrocele
•The spermatic cord appears as an echogenic band on
longitudinal images and ovoid on transverse images as it
passes in the inguinal canal. Color Doppler shows the
testicular artery and pampiniform venous plexus .In the
inguinal canal, the normal thickness of the spermatic
cord is up to 4 mm. The normal inguinal canal does not
contain fluid.
Ultrasound (US) is a readily available and relatively
inexpensive imaging modality that can be performed on
patients at any age without the need for sedation or any
other pretest preparation. US examinations are safe and
there is no significant biologic risk from radiation
exposure.
Different pathologies of the scrotum may have similar
clinical presentation, such as acute scrotal pain or scrotal
mass. US of the scrotum can better guide treatment by
improving the definition of the scrotal pathology. For
these reasons, US became the imaging modality of choice
for evaluation of scrotal pathology, and, in most cases, US
is the first and only imaging needed for evaluation of
scrotal pathology.
•Color Doppler demonstrates capsular
and intratesticular vessels.
In prepubertal testes, it can be difficult
to detect intratesticular flow, but the
capsular arteries are easier to identify. It
is, however.
•The resistive index of the intratesticular
arteries changes with age from high to
low resistive index
Indications for Scrotal Ultrasound
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Pain: trauma, inflammation, torsion
Mass: testicular, extratesticular
Evaluation of a possible hernia and its contents
Search for occult neoplasm in cases of retroperitoneal or
mediastinal lymphadenopathy
Follow-up of previous infections, tumors, lymphoma,
leukemia
Small testes, atrophy
Location of undescended testes
Infertility
Precocious puberty or feminization
•The acute scrotum
Acute scrotal pain is a medical urgency as 12% to 26% of
boys who have it have testicular torsion. The main
differential diagnosis includes testicular torsion, torsion of
appendix testis, and epididymitis.
It is crucial to rapidly diagnose testicular torsion because
prognosis of the testis depends on the duration of
torsion.[Ischemia of the testis can be reversible in the first
6 hours.[US is typically required when the clinical
assessment is equivocal for testicular torsion. Testicular
torsion typically presents as an acute, excruciating scrotal
pain of short duration before a patient arrives in the
emergency room. Physical examination typically reveals
diffuse tenderness, abnormal high and horizontal position
of the testis, and absence of the cremasteric reflex.
Gray-scale findings of testicular torsion may be normal. Testicular
gray-scale abnormalities include testicular swelling or heterogeneous
or decreased testicular echotexture.
Heterogeneous parenchymal echotexture usually indicates testicular
nonviability. Other findings include swelling of the epididymis,
hydrocele, and scrotal skin edema .Epididymal swelling is common in
testicular torsion and, in a few cases, associated with increased
epididymal flow.
A gray-scale study should include evaluation of the spermatic cord.
A coiled spermatic cord could be the only sign for testicular torsion
as perfusion of the testis can be normal in partial torsion (<360°) or
even increased in a case of torsion-detorsion. Evaluation of the
spermatic cord increases the sensitivity for detection of testicular
torsion.
•Decreased testicular blood flow on a color Doppler study
is the most sensitive finding that indicates testicular
torsion. Testicular capsular blood flow may increase and
erroneously suggest, in young boys, the presence of
testicular perfusion. Therefore, prudent examination of
intratesticular blood flow is necessary.
• Spectral evaluation of the blood flow and
documentation of venous and arterial wave flow are
important. Initially, only venous flow may be absent.
Comparing the intratesticular flow to the contralateral
testis is important, as any decrease in perfusion or
change in the waveform may be the first indication of
testicular torsion
Acute torsion of the testis
Rates of testicular salvage by time from start of symptoms.
Davenport, M. BMJ 1996;312:435-437
Copyright ©1996 BMJ Publishing Group Ltd.
Torsion of Testicular Appendix
The appendix testis, a müllerian duct remnant located at the
superior pole of the testicle, is the most common appendix to twist.
The epididymal appendix, located at the head of the epididymis, is a
wolffian duct remnant.
Torsion of testicular appendix can occur at any age but is most
common between the ages of 7 and 12 years. The pain is typically
indolent and not as severe as the pain from testicular torsion.
Duration of scrotal pain is significantly longer than that of testicular
torsion. A palpable tender nodule in the upper pole of the scrotum
and the blue dot sign, which represents the bluish discoloration of
the torsed appendix, are specific signs for torsion of testicular
appendix.
US typically demonstrates an extratesticular nodule with no
vascularity in the upper pole of the scrotum. The maximal diameter
of the torsed appendix varies from 4 to 16 mm. There may be an
overlap between the size of torsed and normal appendixes when
the nodule is smaller than 6 mm.
The torsed appendix leads to secondary inflammation in
the surrounding structures. The epididymis is almost
always swollen with increased perfusion, and occasionally
there is swelling and increased perfusion of the testis.
Other findings include scrotal wall edema and hydrocele.
In some cases, when the torsed appendix is not identified
by US, the findings cannot be distinguished from acute
epididymitis.
Treatment includes analgesic and anti-inflammatory
medications. Surgery is reserved for patients in
excruciating pain who are not responding to medication or
when it is not possible to clinically distinguish from
testicular torsion.
Scrotal appendages. (A) Appendix testis. (B) Appendix epididymis originating
from the surface of an epididymal cyst. Both appendages are seen because of thepresence of
peritesticularfluid. Arrow, appendages. EC, epididymal cyst
Torsed appendix testis.enlarged avascular
appendix testis surrounded by increased blood flow
•Acute Epididymitis
Epididymitis is an inflammation of the epididymis. Epididymitis is
described in response to infection, trauma, vasculitis, or urine
refluxing into the ejaculatory ducts but in most cases is
idiopathic.The diagnosis is often based on clinical presentation of a
few days of acute scrotal pain, swelling, and tenderness of the
epididymis.
Presentation in young boys and those with recurrent epididymitis
should lead to further evaluation with renal US and
cystourethrography for associated anomalies. Anomalies that are
described in association with epididymitis include ectopic ureter to
the seminal vesicles and lower urinary tract anomalies, such as
recto-ureteral fistula and strictures of the urethra. Recurrent
epididymitis can also occur in boys with neurogenic bladder or
functional bladder abnormalities.
Gray-scale US findings of epididymo-orchitis include an
enlarged epididymis. The echotexture of the epididymis
varies, depending on time of evolution, from decreased
to increased echogenicity.
Inflammation of the testis, orchitis, is confirmed by
enlarged testis with heterogeneous echotexture. Indirect
signs of inflammation, such as reactive scrotal wall
edema and hydrocele, are present in most cases.
Duplex US demonstrates hyperemia of the epididymis
and, when orchitis is present, increased testicular
perfusion.
Acute epididymitis
Epididymo-orchitis
Trauma:
The scrotum and its contents may be injured by penetrating or blunt
trauma. Surgical exploration is performed after penetrating trauma,
whereas ultrasound examination
is indicated after blunt trauma .Under these circumstances,the main
role of ultrasound is in the diagnosis of testicular rupture. Early
surgical exploration and repair of a ruptured testis improve testicular
survival because the salvage rate is over 80% when the testis is
repaired within 72 hours,but it drops to 30% thereafter .Reported
accuracy in the diagnosis of rupture of the
testis is in the range of 94% to 100%. Missed or untreated rupture of
the testis may result in an ischemic atrophic testis or secondary
infection. In addition, in cases of unilateral testis trauma, which might
or might not include orchiectomy as treatment, it has been shown that
patients might develop subfertility in association with apoptosis (cell
self-destruction by fragmentation of the nuclear DNA) and abnormal
sperm.
Rupture of the testis
Scrotal hematoma with testis rupture . scrotal wall infiltration (arrows)
and heterogeneous testis on the right side. The left side is normal.
•Germ cell tumors:
Tumors showing a single cell type:
Seminoma
Typical
Anaplastic
Spermatocytic
Embryonal carcinoma
Adult type
Infantile type
Polyembryoma
Choriocarcinoma
Teratoma
Mature and immature
Tumors showing more than one histologic pattern:
Embryonal carcinoma plus teratoma (teratocarcinoma)
Embryonal carcinoma plus seminoma
Seminoma and teratoma
Other combinations
•Tumors of gonadal stroma:
Leydig cell tumors
Sertoli cell, granulosa cell, theca cell tumors
Tumors of primitive gonadal stroma
Mixtures of these three
Adult Unilateral (Occasionally Bilateral) Tumors of the Testis
Classic seminoma in a 46-year-old patient
Testicular teratoma in an infant
Embryonal cell carcinoma predominant in a mixed-cell tumor
Abdominal Burkitt's lymphoma with metastasis to the
testes
Non-Hodgkin large B-cell lymphoma in a 66-year-old patient
Large paratesticular rhabdomyosarcoma in a 14-year-old boy
Chronic epididymitis mimicking a paratesticular mass in a 2year-old boy
•Cryptorchydism
Cryptorchydism occurs in approximately 3% of term male infants with
spontaneous descent in two-thirds of the cases. The incidence of
cryptorchydism rises with prematurity because testicular descent
usually occurs in the seventh month of gestation.
Orchiopexy prevents torsion of the cryptorchid testis and reduces the
risk of trauma to the testis. The exact relationship of fertility to
cryptorchydism and subsequent orchiopexy is controversial. Boys with
cryptorchydism have increased risk of testicular cancer. Orchiopexy
may allow earlier detection of testicular tumors, but it is controversial
as to whether or not orchiopexy reduces the risk of testicular cancer.[
Approximately 20% of undescended testes are nonpalpable and most
of them are located in the inguinal canal .US is highly sensitive for
identifying the inguinal undescended testis. Using US to guide the
surgical approach saves most boys from the need for laparoscopy.
•Inguinal hernia and hydrocele:
Obliteration of the processus vaginalis occurs after the seventh month
of gestation. Failure of the processus vaginalis to obliterate can result
in passage of peritoneal fluid, leading to hydrocele or intestinal loops,
or omentum, leading to inguinal hernia.
The incidence of congenital inguinal hernia is between 0.8% and 4% of
live births. The risk of incarceration is up to 60% in the first 6 months
of life. Right inguinal hernias are more common as the right processus
vaginalis closes later. US can be helpful for inconclusive physical
examination or to evaluate for contralateral involvement. US can show
bowel loops in the inguinal canal or scrotum, and during real-time
imaging it can demonstrate peristaltic activity or movement of fluid
and air bubbles.
Omental hernia is seen as a continuous echogenic structure from the
pelvis to the inguinal canal or scrotum.
A clinically occult contralateral hernia can be found in 88% of cases.
Congenital hydrocele appears as fluid collection surrounding the
anterolateral aspects of the testis, sometimes extending to the
inguinal canal. When the processus vaginalis is completely patent, the
hydrocele is communicating. This leads to elective repair. The
processus vaginalis may obliterate at any point leading to various
types of hydroceles. Closure of the processus vaginalis below the
internal inguinal ring leads to noncommunicating hydrocele, which
usually resolves by the age of 1 year.
Closure of the processus vaginalis below the internal inguinal ring and
above the testis leads to spermatic cord hydrocele. A rare type of
hydrocele is referred to as abdominoscrotal hydrocele. This is a large
communicating hydrocele that protrudes through the internal inguinal
ring into the abdominal cavity and appears as a pelvic cystic mass.
Normal anatomy of the inguinal canal
Omental hernia in a 16-year-old boy
Inguinal hernia containing bowel
•Testicular Calcifications:
Testicular calcifications are of different types. Isolated
calcifications with no associated findings are common and
may represent benign phleboliths, fibrosed-calcified spermatic
granulomas, the end result of previous epididymoorchitis,
or trauma. They are of no clinical significance.
A different situation arises when the calcifications are
multiple, minute, and grouped. They should be considered
highly suggestive of malignancy. Necrotic or hemorrhagic
areas in germ cell tumors may calcify. Embryonal
carcinoma is the most common tumor to present with necrosis and
hemorrhage, whereas seminomas rarely
necrose and calcify. Calcifications may also be seen with
teratoma, but in this case they represent calcified cartilage
or bone fragments.
Testicular microlithiasis is an uncommon, usually
incidental, finding. It is caused by the formation of microliths
from degenerating cells in the seminiferous tubules.
Microlithiasis may occur in healthy patients,
but it has also been found in nonneoplastic conditions such
as Klinefelter’s syndrome, Peutz-Jeghers syndrome, cryptorchidism,
postorchiopexy testis, testicular infarcts, granulomas,
subfertility, infertility, male pseudohermaphroditism,
Down’s syndrome, and pulmonary alveolar microlithiasis.
Testicular microlithiasis has been associated
with germ cell tumors: seminomas, seminoteratoma ,
and intratubular germ cell neoplasia . In cases of
seminoma with pathologic correlation, the area of microlithiasis
was confined to the nontumoral portion of the
testis. Because of the described association of
microlithiasis with neoplasia, the ultrasound diagnosis of
microlithiasis should warrant more aggressive follow-up.
Bilateral microlithiasis of the testes
Seminoma (calipers) in a patient with testicular microlithiasis
•Varicoceles are a dilation and tortuosity of the pampiniform plexus
veins in the spermatic cord or the epididymis .Most
varicoceles are primary and affect adolescents and young adults.
They usually involve the left side, a finding attributed
to the drainage pattern of the more tortuous left
internal spermatic vein into the left renal vein. Bilateral
varicoceles have been reported with an incidence varying
from 10% to 70%. Secondary varicoceles result from
increased intra-abdominal pressure such as from hepatosplenomegaly
and abdominal masses. They are less frequent.
An acute onset on either side, a right varicocele, or
a varicocele in a mature man raises the possibility of an
abdominal or pelvic mass. Varicocele is the most
common single, correctable cause of male infertility, and it
is found in 37% of patients with this problem. Two or more tortuous,
sonolucent tubular structures with a caliber of 2 mm
or more are seen as the hallmark findings in varicoceles.
On the basis of the Doppler tracing during a
Valsalva maneuver, varicoceles have been classified in
two types. The stop type shows only retrograde blood
in the internal spermatic vein. An explanation for this situation
is the presence of competent valves in the pampiniform
plexus. Small and subclinical varicoceles are usually
of this type. The shunt type shows both retrograde and
antegrade (physiologic) blood flow in the same vein. This
phenomenon is explained by the presence of incompetent
valves in the pampiniform plexus that allow communication
and collateral circulation by way of the deferential and
cremasteric veins. Moderate-to-large varicoceles display
this pattern.
Ali shahbazi