ANATOMICAL REMARKS OF THE SPERMATIC CORD AND SCROTAL TUNICS
The SC is a cord like structure within the male anatomy that runs from the abdomen to the testes through the inguinal canal.
It is formed at the opening of the inguinal canal,
known as the deep inguinal ring,
located laterally to the inferior epigastric vessels,
passes through the inguinal canal,
and continues forward and downward.
It exits through the superficial inguinal ring,
finishing inside the scrotum,
at the posterior border of the testicle.
SC content ( Fig. 1 )
• Ductus deferens
• Cremaster muscle
• Arteries and veins:
Ø Artery of the vas deferens,
which rises from the inferior bladder artery.
Ø Testicular artery,
which originates in the abdominal aorta.
Ø Cremasteric artery,
which rises from the inferior epigastric artery.
Ø Pampiniform venous plexus (equivalent to the testicular vein,
which drains into the testicular vein).
• Nerves:
Ø Genital branch of the genitofemoral nerve,
which innervates the cremaster muscle.
Ø Sympathetic nerve fibers,
with arteries,
and parasympathetic with the vas deferens.
• Lymphatic vessels
Spermatic cord covers
The contents of the SC are bound together by three fascial layers that are all derived from the anterior abdominal wall.
This is explained by the descent of the testicles,
which pull down the fascial layers as they migrate from the abdominal cavity into the scrotum during their embryological development.
These three layers,
from deeper to more superficial,
are (Fig. 2) :
• Internal spermatic fascia.
The deepest structure,
derived from the transversalis fascia.
• Cremasteral fascia together with the cremaster muscle.
The middle layer,
derived from the minor oblique muscle of the abdomen and its fascia.
• External spermatic fascia.
The most superficial structure,
derived from the aponeurosis of the major oblique muscle of the abdomen.
EMBRYOLOGICAL DEVELOPMENT OF THE SPERMATIC CORD
The formation of the SC begins during the 2nd to 3rd month of gestation,
when the vaginal process,
which is an evagination of the peritoneum,
formed in turn by fascial extensions of the abdominal wall,
elongates to the scrotum.
Subsequently,
between the 7th and 9th month of gestation,
hormonal stimulation causes the descent of the testes and an obliteration of the vaginal process occurs,
resulting in the closure of the deep inguinal ring (superiorly) and the adjacent part of the testis (inferiorly).
Atresia of the vaginal process between the constrictions formed superiorly and inferiorly (funicular process) also occurs ( Fig. 3 ).
ULTRASONOGRAPHY OF THE SPERMATIC CORD
On ultrasound,
the SC is situated just below the skin.
It is a tubular structure within we can detect its vessels with color Doppler.
Sometimes it can be difficult to differentiate from the surrounding soft tissues of the inguinal canal ( Fig. 4 ).
PATHOLOGY OF THE SPERMATIC CORD
Persistence of the vaginal process
It occurs in 20% of newborns,
though is more common in preterm infants.
It favors the development of cryptorchidism,
hydrocele of the SC and indirect inguino-scrotal hernia.
On ultrasound,
the two collapsed layers of the vaginal tunic are seen as iso-hyperechogenic linear bands that extend from the inner inguinal ring to the scrotum,
which in the absence of associated alterations,
may go unnoticed.
The alterations that are associated to the persistence of the vaginal process are:
1.
Cryptorchidism
Ultrasound is sometimes useful to determine the location of the testis ( Fig. 5 ).
The testis can be found at any point along the path of testicular descent from the retroperitoneum to the scrotal sac,
or more rarely be ectopic.
In the majority of cases (80%),
they are located in the inguinal canal or pre-scrotal.
In 16% of the cases,
they are located in the abdominal cavity,
and in up to 4% of the cases,
they can be absent (anorchia).
Cryptorchidism may sometimes be associated with distal hydrocele.
2.
SC Hydrocele
There are several types of hydrocele (Fig. 6).
The presence of fluid in the SC as a result of an aberrant closure of the vaginal process is called cord hydrocele,
and 2 subtypes can be seen:
• Funicular Hydrocele.
Consists of an altered constriction of the deep inguinal ring with closure above the testis.
It may contain fibrous adhesions (partial constrictions and inflammatory changes) and be associated with indirect hernia ( Fig. 7 ).
• Cystic hydrocele or SC cyst.
A round or ovoid fluid collection between two constrictions which does not communicate with the peritoneum or fluctuates with intra-abdominal pressure (unlike communicating and funicular types).
Ultrasound shows an anechoic well defined avascular oval mass ( Fig. 8 ) located in the groin along the cord,
above and separated from the testis and epididymis.
It is important to differentiate this from scrotal hydrocele,
since the management is different.
In addition,
it is essential to inform the surgeon whether fluid extends from the pelvis to the scrotum or not (communicating hydrocele),
since the latter is treated as an inguinal hernia.
3.
Inguinoscrotal hernia
A common paratesticular mass which may contain small bowel or colon,
with or without omentum,
or just omentum.
It occurs more frequently on the right side due to the later closure of the inguinal canal,
although it may also be bilateral,
which is the reason why an ultrasound study should include both canals.
Three types of inguinoscrotal hernia are described:
• Reducible.
• Strangulated.
It cannot be reduced with the standard maneuvers.
• Incarcerated.
When there is vascular compromise that,
if persistent,
causes necrosis.
On ultrasound,
hernias can be identified by the presence of bowel loops either with connivent valves,
haustra or peristalsis ( Fig. 9 ).
The herniated omentum is seen as a hyperechogenic structure with internal vessels.
It is necessary to differentiate this from a lipoma of the cord,
which is seen as a well-defined or encapsulated echogenic mass that is lateral or posterior to the SC,
unlike the hernias that originate anterior to the cord.
Vascular pathology of the spermatic cord
1.
Varicocele
The pampiniform venous plexus is located behind the testis and accompanies the epididymis and the vas deferens within the spermatic cord.
It is formed by the veins that drain the testes,
which caliber oscillates between 0.5 and 1.5 mm,
with a main drainage vein of up to 2 mm in caliber.
The dilation,
tortuosity and distention of these veins,
with a diameter exceeding 2 mm,
is called varicocele.
The pampiniform plexus results from the fusion of the spermatic veins.
The right spermatic vein drains to the inferior vena cava,
while the left spermatic vein drains,
at right angles,
in the right renal vein,
which later leads to the inferior vena cava.
Venous blood flow is controlled by valves.
Defective valves or compression of the veins by adjacent structures can cause dilation of these veins and lead to varicocele.
In the majority of cases,
varicocele is extratesticular,
although in 2% of cases it appears intratesticular.
The veins that are most affected are those on the left side,
although it can also occur on the right or be bilateral.
On physical examination,
a contorted soft mass can be found along the spermatic cord.
On ultrasound examination,
valsalva maneuver during Doppler exploration is recommended as it increases the sensitivity of the technique and allows for the detection of retrograde blood flow ( Fig. 10 ).
Types of varicocele:
- Idiopathic.
It occurs when the venous valves do not function properly.
- Secondary.
It originates from extrinsic compression of the venous drainage of the testis,
which may be due to different causes,
mainly tumor compression.
The presence of a secondary varicocele in a patient over 40 years requires ruling out the presence of a pelvic or abdominal malignancy.
A non-malignant cause of secondary varicocele is the so-called "Nutcracker Syndrome",
in which the left renal vein is trapped between the aortic artery and the superior mesenteric artery,
leading to an increased pressure that transmits in a retrograde fashion to the left side of the pampiniform plexus.
2.
Torsion of the spermatic cord
SC torsion and acute epididymo-orchitis are the most frequent causes of acute scrotal pain.
There are two types of SC torsion: extravaginal,
in neonates,
less frequent,
and intravaginal,
the most common (65% - 80% of all torsions),
which usually affects males under 30 years.
Intravaginal twisting occurs within the vaginal tunic.
A long mesorchium and bell-clapper deformity are predisposing factors.
The clap deformity of the vaginal tunic completely surrounds the epididymis,
the distal SC and the testis rather than inserting into the posterolateral testicular surface ( Fig. 11 ).
The ultrasound changes in the gray scale begin to appear between the first 1 to 6 hours.
At first,
there is an increase in the testicular size with preservation of the echogenicity,
but over time,
it becomes more heterogeneous and hypoechogenic,
indicating no viability ( Fig. 12 ).
The position of the long axis of the testicle may be altered.
It is important to confirm the diagnosis by finding a rotation of the cord,
and depict the concentric disposition of the layers that make up the torsion ( Fig. 13 ).
The epididymis may be hypertrophied and hyperechogenic due to hemorrhage.
Hydrocele and skin thickening are reactive to torsion.
There may also be a hematocele.
Color Doppler is the most specific technique for the diagnosis of torsion.
The blood flow in the affected testis is absent or clearly inferior to the contralateral testis,
and,
compared to this,
decreased systolic and decreased or reversed diastolic velocities can be seen.
In the subacute phases there may be an increased flow in the periphery of the testis.
In the late stages,
the testicle decreases in size and echogenicity (atrophy).
It is important to differentiate SC torsion from torsion of the testicular appendix,
another cause of acute scrotal pain.
The testicular appendix torsion is seen on ultrasound as a hypoechoic avascular mass ( Fig. 14 ),
adjacent to a normal testicle,
with normal intratesticular blood flow but with an increased peripheral perfusion.
Less frequently it may be seen as an extratesticular avascular echogenic mass,
between the head of the epididymis and the upper pole of the testis.
3.
Hematomas of the spermatic cord.
The presence of an exclusive blood collection in the spermatic cord is infrequent,
and usually secondary to surgical repair of an inguinal hernia,
although it may also occur after trauma,
anticoagulant treatment,
rupture of a varicocele or retroperitoneal hemorrhage.
On ultrasonography,
an increase in the cord volume,
and occupation of the cord by an echogenic collection ( Fig. 15 ),
that may contain partitions and loculations,
can be seen.
With color Doppler ultrasound,
it is possible to demonstrate secondary testicular ischemia when the hematoma is large .This requires urgent surgical intervention.
Inflammatory pathology
1.
Funiculitis.
The inflammatory involvement of the SC is usually associated with epididymo-orquitis.
On physical examination,
the cord is thickened and painful on palpation.
Ultrasound shows SC thickening and ectasia of the pampiniform plexus veins with increased flow on color Doppler ( Fig. 16 ).
2.
Abscess.
It is a rare complication of acute epididymo-orchitis.
Cases secondary to acute prostatitis and coronary angiography (via the femoral artery) have also been described.
Abscesses are seen as heterogeneous avascular hypoechogenic collections with an increase in the surrounding vascularity ( Fig. 17 and Fig. 18 ).
Tumor pathology
Paratesticular tumors account for between 7% and 10% of intrascrotal masses,
and from all of these,
SC and those of the scrotal tunica represent between 75 and 90% of the total.
They are characterized by their unilateral location,
firm consistency,
slow growth and variable size.
The main differential diagnoses includes: inguinal hernia,
hydrocele and chronic epididymitis.
SC tumors are infrequent,
and the anatomical elements that constitute the cord give rise to a great histological diversity.
They are classified in:
1.
Primary tumors
Benign.
These constitute 75% of the masses of the SC.
Lipoma is the most common benign tumor and can appear at any age.
On ultrasound,
they are well-defined,
homogeneous and hyperechogenic masses,
although echogenicity can be variable ( Fig. 19 ).
Other benign tumors include leiomyoma,
lymphangioma,
dermoid cyst,
rhabdomyoma,
fibroma,
angiofibroma,
angiofibrolipoma,
neurofibroma,
fibrous hamartoma and ganglioneuroma.
Malignant.
Sarcomas are the most frequent (rhabdomyosarcoma,
leiomyosarcoma,
liposarcoma ( Fig. 20 and Fig. 21 ),
malignant fibrohistiocytoma and fibrosarcoma.
In adults,
there is a predominance of leiomyosarcomas whereas in children rhabdomyosarcomas are more prevalent.
2.
Secondary or metastatic tumors: most frequently from the gastrointestinal tract (stomach and colon),
pancreas,
prostate,
and kidney.
The depiction of a solid,
vascularized,
tumor-like lesion on the ultrasound usually requires surgical excision to confirm the diagnosis.