Small Parts: Scrotum - SD

Introduction

Hello, my name is Harriet Paul Thiel,
and I'm a radiologist at Children's Hospital in Boston
and at Harvard Medical School.
I'm going to be talking to you about the small parts, scrotum ultrasound imaging.

Objectives

The objectives of my presentation to you are
to review the normal anatomy
and doppler flow patterns of scrotal structures
and to discuss the role of ultrasound in the evaluation
of acute scrotal pain, including testicular torsion,
epididymo-orchitis, torsion of the testicular appendages,
scrotal edema, scrotal trauma, and inguinal scrotal hernia.

Normal Anatomy

Here we have several diagrams describing the anatomy
of the testis and the scrotal structures.
To our left, we see a sagittal section of the testis,
which demonstrates the presence of a tunica albuginea,
which is a thick fibrous coat
that protects the testes from trauma.
And you can appreciate the lobular architecture
of the testes, which is divided
by fibrous septa into multiple lobules.
These lobules contain the seminiferous tubules, which drain
through straight tubules into the rete testis,
which is located here in the posterior aspect
of the testicle, which in turn drain directly
into the epididymis via the efferent ducts, which in turn
are connected to the ductus deferens,
which runs in the spermatic cord.
In the central diagram, we see the testicle as well
as the epididymis with its head, body,
and tail draped over it, as well as the spermatic cord,
which contains the ductus
deferens, as well as the testicular artery
and the pampiniform plexus of draining veins.
On the right, we see the testicle with its appendages,
including the appendix testis, the appendix of the epididymis,
which are vestigial embryonic structures,
and the testis, as you know, is suspended,
and surrounded by a small amount of fluid
within the tunica vaginalis, which consists
of both a visceral and a parietal layer.

Arterial and Venous Supply

In these diagrams, we once again can appreciate the arterial
supply to the testis,
which comes from the testicular arteries seen here
arising from the abdominal aorta.
In addition, it's important to recognize
that the scrotal structures receive their
arterial supply via branches
of the inferior epigastric artery
and the deferential artery, which arises,
from branches of the vesical artery.
These arterial branches supply the peritesticular tissues,
but not the testicle itself.
And this is an important item to keep in mind
when evaluating patients with acute scrotal trauma.
In the middle diagram, we see the venous drainage
of the scrotum, the left
and right testicular veins drain respectively into the left
renal vein and into the vena cava.
Lower down you see the pampiniform plexus,
which drains directly from the testis.
And from there into the testicular vein.
On the right we have a more detailed diagram
of the arterial supply of the testicle.
We see the testicular artery,
coming down
and running around the testicle as the capsular artery,
which in turn gives off multiple centripetal branches,
which then double back as recurrent rami.

Normal Ultrasound Appearance

Pre-pubertal Testes

These images demonstrate the normal pre-pubertal testes,
which are paired ovoid structures that
are homogeneous in echogenicity with the possible exception
of the linear echogenic mediastinum testis on each side
with current equipment.
Most of the time we can readily detect the vessels
of the testis with color doppler,
and when we analyze the vessels using spectral doppler,
we can appreciate flow
as in this testicle throughout the cardiac cycle,
which is seen in many boys.
However, it's not abnormal
to only appreciate a systolic peak,
and that's most common in the very young boys with
small testes with relatively slow flow.

Post-pubertal Testes

Once a patient or a
normal boy reaches puberty,
and the testes are of four ccs in volume
or greater, then the flow is always antegrade
as you see here, and it would be highly abnormal to only
appreciate a systolic peak.
And here again you see in the post-pubertal testes
that the echogenicity is very similar
to the pre-pubertal testes
and you can readily appreciate the vessels within the
parenchyma with color doppler.

Epididymis

The epididymis can also be appreciated.
On the sagittal view, we see the head of the epididymis
as a conical structure adjacent to the upper pole
and the tail often can be appreciated as well.
It's harder to see the body
of the epididymis in the normal subject because it is very thin
and it blends in imperceptibly with the
parenchyma of the testis itself.
The body will be located either in the near
or the far field, depending on the relationship
of the testicle to the position of the transducer.
With color doppler, we often can pick up flow in the head
of the epididymis as well.

Testicular Appendages

The testicular appendages are harder to see
because they are very small
and we generally appreciate them only
when they are surrounded by fluid as we see here
where there are small hydroceles on each side.
This is the testicle
and we see the testicular appendage attached
by a very thin delicate stalk
because it is surrounded by fluid.
On the right we see a very enlarged heterogeneous swollen
epididymis and the epididymal appendage also attached
via a thin stalk.

Testicular Torsion

Testicular torsion is a twisting of the spermatic cord
that compromises testicular circulation.
It may be extra vaginal or intravaginal.
And here we have an image of a young man with a very swollen
left testis due to torsion.
The extra vaginal form of testicular torsion consists
of a twisting of the scrotal spermatic cord.
As you see in the schematic diagram to the right,
it is less common than the intravaginal form
and occurs in neonates and infants.
No one is quite sure why it occurs,
but it is thought that the spermatic cord in testis are
loosely attached to the surrounding structures,
thereby permitting torsion to occur.
The intravaginal form is a twisting
of an excessively mobile testis.
It is seen in children and adolescents
and in this type of torsion,
the tunica vaginalis inserts abnormally high
on the spermatic cord.
As you can see here, here is an
image of a neonate with testicular torsion.
You see the very swollen right testicle.
Sonographically we see thickening of the skin
and subcutaneous tissues
and a very heterogeneous echogenic testis.
Compared to the normal testicle on the left,
it's not uncommon to have a little bit of fluid,
reactive hydrocele, not only on the abnormal side,
but on the normal side as well.
When we examined the testis with color doppler,
we see normal perfusion on the unaffected side,
whereas on the torsed side there is no flow within the
testicle itself,
but there is flow at the edge
of the testis within the very thickened
erythematous scrotal tissues.

An acute testicular torsion often presents
as we see here, just with diffuse swelling of the testicle,
but no significant change in the testicular
parenchymal echogenicity.
However, when you examine the testis with color,
you can readily appreciate
that there's absolutely no flow within it, whereas there's
excellent perfusion on the unaffected side.

Unlike the neonatal torsion which are often
of longer duration than the acute testicular torsion,
we don't see any swelling
of the soft tissue surrounding the testis or hyperemia.
And here we see the testis at the time of surgery.

Chronic testicular torsion in the older child
and adolescent will present as we see here,
very heterogeneous parenchyma,
a reactive hydrocele probably secondary to hemorrhage with
stranding of echogenic strands within the hydrocele.
And with color doppler, we again see
that there's perfusion at the periphery of the testis,
but no flow within the parenchyma of the testis itself.
And with color doppler,
and spectral analysis,
we don't appreciate any spectral waveform at surgery.
The testis is black when it is incised with a scalpel
as we see here, it does not bleed
and it is completely necrotic.

Torsion of the Testicular Appendages

Torsion of the testicular appendages is the most common
cause of acute scrotal pain
and swelling in the pre-pubertal boy,
and it classically presents
with a very tender nodule at the upper pole of the testis.
As you can make out here in this photograph, there is a
bluish discoloration of the scrotum
and this is characteristic of torsion
of the testicular appendage sonographically.
What we appreciate is increased perfusion of the testis,
epididymis and scrotal tissues.
Here on the sagittal view we see the testicle
with the conical epididymal head and above it.
This other structure
which is not perfused when we examine it with power doppler
and this is the twisted appendix epididymis.
Most of the time there's no need to proceed to surgery.
We can make the diagnosis clinically and with imaging,
but this picture is just to show you what a torsed
appendage looks like at surgery.

Epididymo-orchitis

Epididymo-orchitis is typically not secondary to known causes.
It may occur in the pre-adolescent population
and it's rare to have an isolated orchitis.
We do see isolated orchitis in the setting of mumps,
for example, viral orchitis and following trauma.
But generally speaking, orchitis is associated with epididymitis.
Here on this transverse image of the scrotum,
we see a swollen right testicle.
And on the sagittal view to your left,
we see the very enlarged heterogeneous epididymis.
With color doppler, we see
that there's markedly increased perfusion
to this right testicle compared
to the normal testicle on the left
and the epididymal head as well is extremely hyperemic.
This is also reflected in the spectral waveforms
that we can appreciate here.
Increased amplitude
and velocity of flow on the abnormal right side compared
to the normal left side, complications are relatively rare.
They include abscess, pyocele and ischemia.
Pyocele may occur secondary to a testicular abscess
or maybe due to iatrogenic causes,
whereas ischemia can occur very,
very rarely if there is venous outflow compressed
by the uninflamed epididymis, resulting in ischemia
and ultimately infarction.

Complications

Here we see an example of a patient
with a testicular abscess.
It's pretty well circumscribed as you see on the sagittal
and transverse images with a power doppler.
You see that there's good perfusion of the parenchyma
outside of the abscess,
and this patient was treated conservatively
with antibiotics with a good result.

Here's an example of a pyocele,
a very rare complication in this particular patient.
It was related to perforation of the bowel
after an attempt at intussusception reduction.
We appreciate the testicle
here in the upper left hand corner surrounded by
thick and inflamed tissues.
On this image on the right we don't see the testicle,
but we see the very thickened scrotal tissues
with thick bands traversing the scrotal sac.
With spectral doppler, there's increased amplitude
and velocity of arterial flow within this inflamed tissue
and the flow and amplitude
and velocity are much more striking than that of the
adjacent testicle, which is surrounded by the
infected fluid scrotal.

Scrotal Edema

Scrotal edema is a cause of the painful scrotum in young boys
and may be due to a variety
of inflammatory processes including trauma cellulitis
and Henoch-Schönlein purpura, it may also be idiopathic.
And we see here an example of a young boy with
a swollen mildly hyperemic scrotum.

Henoch-Schönlein Purpura

Henoch-Schönlein purpura is a systemic vasculitic syndrome.
The scrotal symptoms may come on acutely or be gradual,
and they do occur in up to about a third
of patients the testis, the epididymis,
and the spermatic cord may be affected.
Scrotal involvement is generally self-limited and benign
and there is no specific therapy required.
Here is a patient with Henoch-Schönlein purpura
and you'll notice the very massively swollen scrotum.
And if you look very carefully,
you can also appreciate a bluish purplish discoloration
of the scrotal skin and also in the left inguinal
region due to the purpura.
And this is the purpura, which is a hallmark
of this disorder sonographically, we see
that there's a tremendous thickening of the skin
and subcutaneous tissues.
The epididymis are enlarged as well,
and with color doppler, there's massively increased flow
to the scrotal soft tissues as well as hyperemia
of the testes and epididymis.

Scrotal Trauma

Scrotal trauma accounts for less than 1%
of all traumatic injuries annually in the United States,
and it is thought that severe injury is rare due
to scrotal mobility.
The right testis is more frequently injured than the left,
and this is thought to be due to the fact
that the right testis is generally higher riding than the
left and therefore more likely
to be trapped against the pubis.
The peak age range for scrotal trauma is between 10
and 30 years of age.
The mechanisms of scrotal trauma include penetrating injury,
which will present immediately
or blunt trauma, which may have a delayed presentation,
which is common in the absence of testicular dislocation
or when there is a multi-system injury
and the scrotum tends to be overlooked.
It will manifest a scrotal wall ecchymosis, scrotal
swelling, scrotal, and intra-testicular hematoma.
Blunt trauma is more common than penetrating injury.
It's usually unilateral
and it's caused by a straddle injury or a direct blow.
The scrotal contents will be compressed against the
inferior pubic ramus.
Management is based on testicular integrity.
Most injuries are minor and are treated conservatively.
However, the tunica albuginea
of the testis may rupture resulting in a severe crush injury
to the testicular parenchyma.
Operative indications include uncertainty in diagnosis
after clinical and imaging evaluation.
Clinical findings consistent with testicular injury,
disruption of the tunica albuginea and
or absence of testicular perfusion on Doppler ultrasound imaging, it's often very difficult
to examine these patients due to marked tenderness
and swelling and difficulty
of scrotal examination may prevent detection
of testicular rupture.
Early operative intervention,
however, will decrease the incidence
of delayed orchiectomy due to an unrecognized rupture.

Testicular Rupture

And here we have an example of a testicular rupture.
And you can see that there's a divot here in the
center of the testicle.
Heterogeneous echogenicity of the testicular parenchyma
with loss of contour definition has been shown
to be a highly sensitive
and specific ultrasound sign of testicular rupture.
It's also important to remember
that ultrasound does not do a particularly good job in
identifying a torn tunica albuginea.
So if we apply the principle
of detecting a contour abnormality
and heterogeneity of the parenchyma, we would
surely suspect a rupture
of the tunica in this patient, which was indeed the case.
You can see that there,
the contour is quite abnormal on the sagittal view.
There's a large intra-scrotal hematoma,
which we can also appreciate on this transverse view.
And note also the maturity
of the parenchyma with color.
There's a portion of the testis that is perfused,
but there's a large portion that does not appear
to be perfused, and the arterial waveform is not normal
either we see flow in systole,
but then it peters out during diastole
and actually is absent in end diastole.

Isolated Testicular Hematoma

An isolated testicular hematoma result in testicular
enlargement with focal areas of increased
or decreased echogenicity depending on the age
of the lesion, normal testicular perfusion will be
seen by doppler ultrasound except at the sites of hematoma
and there will be displacement of the peripheral vessels.
So here's a patient with an isolated testicular hematoma.
Notice that unlike the case of the tunica albuginea rupture, the overall shape
of the testis is preserved
and we just have this isolated area,
or actually a couple of areas of absent perfusion,
which we see well documented with color doppler.
But the rest of the parenchyma does
demonstrate normal perfusion.

Hematocele

Hematocele is a collection of blood within the tunica
vaginalis that may occur with
or without associated testicular rupture.
A large collection will require aspiration since testicular
compression may lead to ischemia and infarction.
Minor trauma resulting in hematocele,
raises the possibility of an underlying tumor.
And in these instances, it's really important to
follow the hematocele to resolution in order to ensure
that there's no underlying testicular tumor,
which would have led to the bleed in the first place.
Here we see a patient with a hematocele.
Here's the testicle, which is very dwarfed,
very much dwarfed by this very extensive bleed
surrounding it.
Here we see more echogenic clot
and here we see more liquid components
with some stranding with color doppler.
We see that the testicle itself appears to be well perfused
with a normal arterial waveform seen with spectral analysis.

Inguinal Scrotal Hernia

Finally, I'd like to discuss inguinal scrotal hernia.
Incarcerated hernias may cause acute
scrotal pain or swelling.
Most of the time a hernia is clinically obvious
and there's no need for imaging.
However, ultrasound can be useful in patients
with scrotal enlargement as we see here
of uncertain etiology.
Upon sonographic examination, the presence
of peristalsis will favor viable bowel,
whereas its absence suggests the presence of ischemia.
Here we see an example of an inguinal scrotal hernia.
On the sagittal view we have the scrotal sac
with the testicle,
and then above it we see a loop
of bowel extending right down into the scrotal sac just
above terminating just above the upper pole of the testis.

Summary

So in summary,
we have reviewed the normal scrotal anatomy
and Doppler flow patterns
and have also discussed sonographic evaluation
of acute scrotal symptoms in testicular torsion,
epididymo-orchitis, torsion of the testicular appendages,
scrotal edema, trauma, and inguinal scrotal hernia.
Thank you.