Scrotum

what are the three major structures contained in the scrotum?

what are the three major structures contained in the scrotum?

spermatic cord, epididymis, testes

tunica vaginalis

serous covering of testis

a double-layer extension of the peritoneum that separates scrotal layers from the tunica albuginea

covers testes except at the back where the epididymis is attached

what are the three layers of the tunica vaginalis

parietal, visceral, vaginalis sac

What are the three ducts that sperm travel through to exit the body?

epididymis, ductus (vas) deferens, urethra

What are the accessory sex glands?

seminal vesicles, prostate, bulbourethral glands

tunica albuginea

dense, fibrous capsule covering testis

extends inward and divides each testicle into 250-400 lobules

lobules

internal compartments formed by projections of tunica albuginea

contain seminiferous tubules and interstitial cells (Leydig) with their bases are near surface and apices converge toward mediastinum testis

seminiferous tubules

Each lobule contains 1-3 of these tightly coiled tubules

Produce sperm by spermatogenesis

sustentacular (Sertoli) cells

found in the tubules and among the sperm cells, form the blood-testis barrier need for immunity

rete testis

seminiferous tubules converge to form rete testis

located at testicular mediastinum

mediastinum teste

Thickened portion of albuginea along posterior border of testis that projects inside it and creates a linear fibrous structure

Point where tubules converge and exit into rete testis and efferent ducts

appendix testis

a remnant tissue after paramesonephric duct degenerates

small portion at cranial end

ductus/vas deferens

Muscular cord designed to pump sperm into the prostatic segment of the urethra

Ascends along posterior border of testis and enters pelvic cavity thru the inguinal canal where it travels over the side and posterior surface of bladder

Seminal vesicles connect to vas deferens to form ejaculatory ducts

Stores sperm for up to several months

spermatic cord

Supporting tube of testes

Contains blood vessels, nerves, lymph nodes, cremaster muscle

Attached to posterior border of testis

Travels through inguinal canal toward posterior surface of bladder where it joins the seminal vesicle duct to form the ejaculatory ducts

epididymis

comma shaped structure that curves along posterior border of testis

consists of head, body, tail, appendix epididymis, and efferent ductules

epididymis head

(globus major) most superior aspect, consists of first part of efferent ducts that transport sperm out of testes(globus major): most superior aspect, consists of first part of efferent ducts that transport sperm out of testes

epididymis body

(corpus) contains ductus epididymis, which is a tightly coiled single tube where the efferent ducts empty into

epididymis tail

(globus minor) distal part of epididymal ducts that exit and continue as ductus (vas) deferens in spermatic cord

appendix epididymis

mesonephric duct persists to form the ductus deferens, except for its most cranial portion, which becomes this structure

efferent ductules

pass from the rete to enter upper portion of the epididymis

normal testicle size

length= 4-5cm

width= 2-3cm

AP= 2-3cm

weight= 12.5-19g

symmetric, oval-shaped glands with smooth contour

arterial blood supply to the testes

Aorta → Testicular Artery → Travels in retroperitoneum & enters inguinal canal in spermatic cord where it branches into → Capsular Arteries (run in layer beneath tunica albuginea) and surround testis as → Centripetal Arteries (run into testicular parenchyma toward mediastinum)

testicular flow pattern

low resistance arterial flow

broad systolic peaks and high levels of diastolic flow throughout cardiac cycle

RI average: 0.55-0.64

arterial blood supply to scrotum and epididymis

Inferior Epigastric Artery → Cremasteric (External Spermatic) Artery (spermatic cord)

Inferior Vesical Artery → Deferential Artery (spermatic cord) courses through the tail of epididymis → divides into capillary network

scrotum and epididymis flow pattern

does not supply testicular tissue

high-resistance arterial flow

narrower systolic peaks and diminished or absent diastolic flow

venous blood supply to testes

Intratesticular Veins exit mediastinum → Venous Outflow → Pampiniform Plexus → Internal Spermatic Vein → drains into:

Left Internal Spermatic Vein → Left Renal Vein → IVC

Right Internal Spermatic Vein → IVC

Typical venous flow pattern

lymphatic drainage of testes

Lymph plexuses under tunica vaginalis, testis, and epididymis

↓

Traverse in spermatic cord

↓

Follow testicular vessels

↓

Lumbar (para-aortic) nodes as high as renal veins

spermatogenesis

Sperm formation

Is the sequence of events in the seminiferous tubules that leads to the production of male gametes: sperm or spermatozoa.

The process begins during puberty, around the age of 14 years & continues throughout life

healthy adult male makes about 400 million sperm a day

hormonal regulation of testicles: reproductive function

brain-testicular axis

hormonal regulation of testicles: spermatogenesis & testicular androgen

hypothalamus, anterior pituitary gland, testes

the amount of testosterone and sperm produced by the testes reflects a balance among three sets of hormones:

Gonadotropins: which directly stimulate the testes

GnRH: which indirectly stimulates the testes via its effects on FSH and LH release

Testicular hormones (testosterone & inhibin): which exert negative feedback

the more testosterone produced, the more sperm produced

function of the scrotum

Supporting structure for testes

Regulates temperature of testes

Holds testicles outside the body where the temperature is more optimum for sperm maturation

Contraction of the cremaster muscles maintains scrotum position outside the pelvic cavity

function of epididymis

Site for sperm maturation, which requires 18 hours to 10 days

Site of sperm storage

Stores sperm until orgasm, then propels sperm from testicle to vas deferens within spermatic cord

exocrine function of testicles

producing spermatozoa (male germ cells)

endocrine function of testicles

synthesizing and secreting testosterone

human chorionic gonadotropin (HCG)

can be produced by tumors which can raise its levels in blood

what cancers is HCG elevated in?

seminoma

embryonic cell tumors of testes

testosterone

Main androgen secreted by Leydig cells

Induces puberty in males

Maintains male secondary sex characteristics

what pathologies is testosterone elevated in?

Testicular tumor

Adrenal hyperplasia

Benign or malignant tumors of testes, adrenal, pituitary

Adrenal tumor

what pathologies is testosterone decreased in?

Orchiectomy (removal of testes)

Testicular or prostate cancer

Cirrhosis of liver (no metabolism of testosterone)

Primary or secondary hypogonadism (gonads not fully developed)

normal ultrasound appearance of testicles

Homogeneous with medium-level echoes

Smooth walls

Each testis and epididymis must be compared for matching size and echogenicity

mediastinum testis

Highly echogenic linear structure peripherally located in posterior-superior aspect of testis (parallel to epididymis)

appendix testis

Small ovoid structure beneath head of epididymis

What is this structure?

mediastinum testis

What is this structure?

appendix epididymis

ultrasound appearance of epididymis

Head: Isoechoic or slightly more echogenic than testis

Body: Isoechoic or slightly less echogenic than head and testes

Tail: Slightly thicker than body

testicular artery doppler evaluation

low resistance (needs constant blood supply)

broad systolic peaks and high diastolic flow

deferential artery doppler evaluation

high resistance

narrow systolic peaks and low diastolic flow

cryptorchidism

undescended testis

etiology of cryptorchidism

Normally testes descends into scrotal sac at 8 months gestational age

where are the ectopic locations of cryptorchidism in children?

inguinal canal

where are the ectopic locations of cryptorchidism in adults?

small testis with normal echogenicity usually found in the inguinal canal

what are the potential concerns with cryptorchidism?

increased chance of malignancy (seminoma) in undescended testicle

infertility

cryptorchidism on ultrasound

Malpositioned testes situated anywhere along the normal track of descent from the retroperitoneum to scrotum

Most commonly found at or below level of inguinal canal

Appear more echogenic than muscle

Identify this pathology

cryptorchidism

what is acute scrotum pain most commonly caused by?

epididymitis or orchitis

torsion cannot be ruled out

testicular torsion

Twisting of the spermatic cord that results in loss of blood supply to the testis and blocks venous drainage resulting in venous congestion within testicles

what is testicular torsion caused by?

Caused by developmental weakness of mesenteric attachment of spermatic cord to the testis and epididymis

bell clapper deformity

seen in testicular torsion

This abnormal development allows testicle to fall forward in scrotum and rotate freely within the tunica vaginalis creating this deformity

testicular torsion etiology

Spermatic cord and/or testicle twist

Limits vascular flow and drainage, which compromises blood supply and results in ischemia

Represents 20% of scrotal disease in post pubertal males

Occurs most commonly during adolescence (peak incidence at 14 years)

Surgical treatment within 4-6 hours in necessary as testicular viability can be lost very quickly

acute torsion signs & symptoms

Sudden onset of extreme testicular pain

50% of patients have nausea and vomiting

May have low-grade fever

Left testicle is more often affected than right testicle

After 24-48 hours, pain usually disappears indicating that the testicle is dead

ultrasound appearance of torsion after a period of ischemia

Testis and epididymis appear enlarged with decreased echogenicity, inhomogeneous

Scrotum appears with thickened wall, edematous, and hypervascular

torsion on doppler

Testicular ischemia is noted by complete or near-complete absence of detectable blood flow in symptomatic testicle

After 24 hours, absent blood flow to testis is seen

If no flow is detected on color Doppler, there is complete torsion

chronic torsion etiology & symptoms

Spermatic cord and testicle twist, resulting in ischemia to testicle and complete cessation of blood flow

classified after 10 days

history of severe acute pain in the past

chronic torsion on ultrasound

Heterogeneous appearance of testes

Peripheral rim or normal appearing testicular tissue

Testicle atrophies (gets smaller) with the epididymis remaining enlarged and hyperechoic

chronic torsion on doppler

no blood flow

unable to obtain arterial and venous waveforms

identify this pathology

enlarged epididymis and testicle with acute torsion

no blood flow visualized on color Doppler evaluation

identify this pathology

left: Heterogeneous testicle with peripheral normal appearing tissue consistent with chronic infarction

right: Inhomogeneous echotexture of testicle with chronic infarction

torsion-detorsion & partial torsion signs and symptoms

Acute and intermittent sharp testicular pain and scrotal swelling

Interspersed with long asymptomatic intervals

torsion-detorsion & partial torsion on ultrasound

During spontaneous detorsion, there is increased perfusion demonstrated as hypervascularity with low-resistance flow patterns within the testicles

Testis may be enlarged

Focal infarcts may or may not be present as hypoechoic areas

torsion of appendages etiology

Loss of blood supply to the appendix testis or appendix epididymis

Over 90% of torsed appendages involve appendix testis

Peak incidence between 7-14 years of age

torsion of appendages signs & symptoms

acute scrotal pain

mimics testicular torsion

torsion of appendages on ultrasound

Testis is normal on color Doppler

Appearance of torsed appendage varies:

• Large circular hyperechoic mass with central hypoechoic area

• Enlarged circular heterogeneous mass adjacent to a normal testis or epididymis

Increased periappendiceal flow and absent central flow demonstrated on color Doppler

identify this pathology

torsion of appendages

testicular rupture etiology

Rare

Occurs when the capsule, the tunica albuginea, is torn by trauma

Associated with athletic injuries, industrial, and motor vehicle accidents

testicular rupture on ultrasound

Contour abnormality due to irregular fibrous tunica albuginea

Extrusion of testicular contents into scrotal sac

Hematocele and hematoma may be present

Infarction of testicular contents

identify this pathology

testicular rupture due to blunt trauma featuring a hematoma (left) and irregular contour of disruption of tunica albuginea (right)

epididymitis etiology

Most common cause of acute scrotal illness/pain

Caused by retrograde spread of bacterial infection from bladder or prostate

Associated with prostatitis

Sexually transmitted organisms including gonococci and Chlamydia are common causes in young men

epididymitis signs & symptoms

slight fever, chills, heavy sensation in affected testicle, testicle sensitivity to touch or pressure, enlargement of testicle, abdominal/pelvic pain, blood in urine, discharge from penis, painful ejaculation, burning sensation during urination, frequent urge to urinate

acute epididymitis on ultrasound

Enlarged, hypoechoic epididymis

Mainly involves head

Entire epididymis involved in 50% of cases

Hypoechoic areas are secondary to edema

Color Doppler may demonstrate increased flow in epididymis

chronic epididymitis on ultrasound

Thickened echogenic epididymis

May contain calcifications

what findings are more suggestive of an infectious process than a tumor?

swelling, epididymal abnormalities, skin thickening, and hydrocele

what is this pathology?

epididymitis

orchitis

Inflammation of testis due to trauma, metastases, mumps, or other (bacterial or viral) infection

orchitis etiology

Isolated orchitis is rare, usually occurs as secondary result of epididymitis

Can be focal or involve entire testicle

Neoplasm must be ruled out by serial US exams or surgery; if it persists, orchitis will resolve but neoplasm will not

orchitis signs & symptoms

Acute scrotal pain, with or without fever

See epididymitis

acute orchitis on ultrasound

Diffuse: decreased echogenicity and increased size

Focal: focal areas of decreased echogenicity

Doppler: Testicular hyperemia, increased number of blood vessels in affected area, increased venous flow in epididymis

chronic orchitis on ultrasound

Thickened tunica albuginea

Echogenic, thickened, irregular epididymis

Both may contain calcifications

Affected testis is smaller

granulomatous orchitis

multiple focal hypoechoic lesions

identify this pathology

orchitis

epididymo-orchitis etiology

Inflammation of the testis and epididymis

20% of epididymitis involves the testis

Testicular involvement can be focal or diffuse

epididymo-orchitis on ultrasound

Hypoechoic area extended from epididymal region

Increased blood flow (hypervascularity) in affected testicle and epididymis

identify this pathology

epididymo-orchitis

what are the benign scrotal masses?

hydrocele, spermatoceles & epididymal cysts, tubular ectasia of rete testis, varicocele, scrotal hernia, scrotal abscess, scrotal hematoma, hematocele, pyocele, tunica albuginea cyst, benign neoplasms

hydrocele

Abnormal collection of serous fluid in potential space between the two layers of tunica vaginalis (between visceral and parietal layers)

hydrocele etiology

Most common cause of painless scrotal swelling

Congenital or acquired, often idiopathic or associated with epididymitis, torsion, trauma (25-50%)

Usually occur in anterior aspect of scrotum and displace testis posteriorly

hydrocele signs & symptoms

painless swelling of scrotum

scrotal mass

hydrocele on ultrasound

anechoic fluid collection

enhanced through transmission

typically surrounding the anterolateral aspects of testis

chronic ones can contain calcifications that produce posterior shadows

scrotal pearls etiology

AKA scrotoliths

Calcifications that often result from inflammatory deposits on the tunica vaginalis that have separated from the lining

May be single or multiple

scrotal pearls on ultrasound

Echogenic free-floating calculus outside testicle

Appear as echogenic foci between layers of tunica vaginalis

May produce posterior shadow depending on size

Visualization aided by presence of hydrocele