UNDER THE FOETAL TESTOSTIRON INFLUENCE GENITALTUBERCLE FORM THEN TESTIS.
testicular descent is initiated at about 10–14 weeks of gestation to about weeks20–23 through the inguinal canal and completed by week 35 in the human
superficial inguinal ring (1), cremasteric muscle (2) and (4) spermatic cord (3), septum scroti (5), tunica dartos (6), vas deferens ( 7), testicular artery (8), branches of the ilio-inguinal nerve (9), deferential artery (10), external spermatic fascia with cremaster muscle and internal spermatic fascia (11), pampiniform plexus (12), epididymis (13), lamina parietalis of the tunica vaginalis testis (14).
The following structures enclose the contents of the scrotum, from outside to inside: scrotal skin, tunica dartos, the tunica vaginalis testis lamina parietalis provides the serous cavity for the testis (cavumserosum testis). The tunica vaginalis testis lamina visceralis is the serous covering of the testicle. The testicular tissue is surrounded by the strong tunica albuginea
The testes are a paired organ in the scrotum,The testicles have a strong organ capsule (tunica albuginea testis).The testicular parenchyma is composed of 250–350 lobules, which drain through the mediastinum testis to the epididymis.The lobules are separated by connective tissue septa (Septula testis) originating from the mediastinum testis. A lobule of the testis consists of one or several seminiferous tubules, which end and start at therete testis [fig. cross section of the testis and epididymis].
Normal tunica albuginea. Longitudinal gray-scale US image of a normal testis depicts a thinechogenic line (arrow) around the testis.
The scrotum consists of a thin layer of skin (<3mm) and underlying fascia. Each hemiscrotum contains a testis with its coverings, epididymis, and spermatic cord. A normal testis measures 5 × 3 × 2 cm in size.In healthy young men the ovoid testis measures 15 to 25 mL in volume. The testicular parenchyma consists of multiple lobules, each of which is composed of many seminiferous tubules that lead via the tubuli recti to dilated spaces, called the rete testis within the mediastinum
2- 3c.m. in anterio posteriorVolume 12.5 – 19 gm in adults.The size of the testicle varies with age, increasing in size from birth to puberty and then decreasing later in life
Transverse view of the testicle in a newborn (left). Sagittal view of an adult testicle (right)
The epididymis is located in the posterolateral aspect of the testicle as a hypoechoic structure discretely heterogeneous. With high resolution, the head, body, and tail is visualized in the mayority of cases. Sagittal view of the body of epididymis (left). Sagittal view of the head of epididymis (right).
The mediastinum of the testis is an echogenic band of variable thickness that extends across in a craniocaudal direction. If imaged at an angle, it may resemble a testicular tumor (1).
Pampiniform plexusTransverse views of the testicle demonstrating anechoic structurescorresponding to the pampiniform plexus.
A small amount of intrascrotal fluid may be normally seen.
The spermatic cord contains the vas deferens, testicular artery, cremasteric artery, deferential artery, pampiniform venous plexus, lymphatic ducts and genitofemoral nerve. At the upper pole of the testis is the appendix testis, a small pedunculated or sessile body similar in appearance to the appendix of the epididymis.
Transverse US scan of the testis shows a normal transmediastinal artery (arrow) as a linear hypoechoic band. Color Dopplerflow US (not shown) revealed flow through the vessel.
The internal spermatic arteries arise from the aorta just below the renal arteries and course through the spermatic cords to the testes, where they anastomose with the arteries of the vasa deferentia that branch off from the internal iliac (hypogastric) artery.
Sagittal and transverse views of testicles on color Doppler.
Testicular rupture. (3a) Longitudinal gray-scale US image of the right testis in a patient with scrotal trauma shows localized disruption of the tunica albuginea (arrows) with associated contour abnormality (arrowheads) and heterogeneous echotexture of the testicular parenchyma (*). (3b) Color Doppler US image depicts an absence of vascularity in the extruded lower pole of the testis (*). Surgical débridement of the inferior pole was performed with salvage of the uninjured part of the testis. (4) Longitudinal color Doppler US image of the right testis in a patient with more severe scrotal trauma shows complete disruption of the tunica albuginea with testicular contourabnormality (arrowheads) and no vascularity. The contralateral testis (not shown) also was ruptured. A bilateral orchiectomy was performed
Intratesticular hematomas. (a) Longitudinal gray-scale US image obtained immediatelyafter blunt scrotal trauma demonstrates a heterogeneous echotexture in the left testis, withan intact surrounding tunica albuginea. (b) Follow-up sagittal US image obtained 12 hours latershows multiple avascular hypoechoic lesions (arrowheads) within the testis. The hematomas weremanaged conservatively.
Testicular rupture.(6) Longitudinal color Doppler US image of the left testis in a patient with scrotal trauma depicts tunica albuginea disruption (arrowhead) with a loss of vascularity in the ruptured portion of the testis (*). Débridement of the avascular portion was performed with salvage of uninjured parenchyma. (7) Transverse color Doppler US image of the left testis inanother patient with scrotal trauma shows disruption of the tunica albuginea (arrow) and aheterogeneous echotexture with an almost complete loss of vascularity. This patient underwentan orchiectomy.
Intratesticular hematoma. Transverse color Doppler US image in a patient with scrotal trauma demonstrates an avascular hypoechoic area (arrow) within the testis. The hematoma was managed conservatively.
Testicular pseudoaneurysm. Color Doppler US image of the right testis in a patient with scrotal trauma demonstrates a focal area with a mosaic of colors (arrow).IntratesticularPseudoaneurysmA pseudoaneurysm is a vascular leak that is surrounded and contained by a pseudocapsule.Intratesticularpseudoaneurysms are extremely rare (39) and may result from either blunt orpenetrating trauma. Gray-scale US demonstrates an anechoic area within the testis, which is filledby a mosaic of colors (typically known as they in-yang sign) indicative of a turbulent flow patternat color Doppler imaging (Fig 12). SpectralDoppler at the neck of the pseudoaneurysmal sacreveals a to-and-fro flow pattern that is diagnostic of a pseudoaneurysm. Rarely, a pseudoaneurysm may be secondary to orchitis; however, to our knowledge, such an occurrence is described in only one published case report
Hematocele. Transverse gray-scale US image of the testis (T) depicts a complex loculatedextratesticular fluid collection with low echogenicity and a fluid-debris level, findings suggestive of a chronic hematocele.
Scrotal wall hematoma. Transverse gray-scale US image depicts echogenic (arrowhead) and hypoechoic (arrow) areas in the scrotal wall after blunt trauma but shows no injury to the testis (T). The scrotal injury was managed conservatively.Scrotal Wall Hematoma.—Scrotal wall hematomas are commonly associated with blunt trauma. They may be identified at US as an echogenic focal wall thickening or as a complex fluid collection within the wall, depending on the time thathas elapsed since trauma (Fig 17). Scrotal wall hematomas usually resolve spontaneously or with conservative management, but those that are very large may require surgical evacuation.
Traumatic epididymitis. Transverse gray-scale (a) and color Doppler (b) US images obtained in a patient with scrotal traumashow an enlarged heterogeneous epididymis (E) with increased vascularity and a small amount of surrounding fluid. T = testis.
HydroceleA hydrocele is the most common cause of scrotal swelling. The normal scrotum contains small amounts of serous fluid between the layers of the tunica vaginalis. Abnormal collection of fluid in the space between the visceral and parietal layers of the tunica vaginalis results in a hydrocele. The fluid collections are usually confined to the anterolateral portions of the scrotum because of the posterior location of attachments of the tunica to the testis and scrotum. Hydroceles may be unilateral or bilateral and can be seen as an isolated finding or in conjunction with acute or chronic pathology. Many of these fluid collections are congenital. Acquired hydroceles are associated with infection, tumors, trauma, torsion and radiation therapy. Hematoceles and pyoceles are complex hydroceles. Sonographically, a simple hydrocele is seen as an anechoic dark fluid collection surrounding the testicle (Figure 3), whereas a complex hydrocele may contain internal echoes with septations and loculations. A chronic hydrocele may also demonstrate internal echoes from cholesterol crystal formation. (1,2,3,6)
VaricoceleA varicocele is a collection of tortuous and dilated veins within the pampiniform plexus of the spermatic cord. They are found in approximately 15 % of adult males and can result in infertility secondary to decreased sperm motility and count. They are due to incompetent valves in the testicular vein. The vast majority of varicoceles are located on the left side and only 1 % are bilateral. The left sided predominance of varicoceles is thought to be due to the long course and angle of entry of the left testicular vein as it empties into the left renal vein. The right testicular vein is shorter and empties directly into the inferior vena cava. Varicoceles are much more apparent when the patient performs a Valsalva maneuver or is standing. Hence, ultrasound should be performed in both supine and standing positions. Sonographically, they appear as multiple anechoic serpiginous tubular or curvilinear structures of varying sizes (larger than 2 mm in diameter) in the region of the epididymis (Figure 4). Power Doppler should be used to confirm flow in the varicocele. (5,6,7)
Testicular TorsionTesticular torsion is a urologic emergency. Prompt diagnosis and early treatment is essential as time is critical for testicular salvage. Torsion is more common in children but can occur in post pubertal males. The majority of testicular torsions result from anatomic defects that lead to redundant spermatic cord and anomalous suspension of the testes in the scrotum. An undescended testicle also increases the likelihood of torsion. A redundant spermatic cord is mobile and during torsion it begins to twist upon itself. As the twisting progresses, venous flow is interrupted initially due to easily collapsible vessel walls and the low intravascular pressure. Venous obstruction is followed by a decrease in arterial inflow, which eventually progresses to complete obstruction. Once the spermatic cord is fully torsed and no blood flow is present, infarction and loss of the testicle can occur quickly. Rapid diagnosis of testicular torsion is critical to preserve fertility. The salvage rates are approximately 100 % at 3 hours, 83-90 % at 5 hours, 75 % at 8 hours, and 50-70 % at 10 hours. The salvage rates decrease to 10 to 20 % when the testicle remains torsed for more than 10 hours. After 24 hours, salvage of a testicle is rare unless there has been intermittent detorsion. Sonographic findings can be variable depending on the duration of torsion and extent of vascular compromise. The testicle can appear enlarged and hypoechoic and the parenchyma of the testicle will become less homogenous when compared with the unaffected testicle (Figure 5). Unfortunately ultrasound may not always be helpful, as sonographic findings may be subtle early in the course. Color Doppler or power Doppler may be helpful to identify flow patterns in the acutely tender testicle (Figure 6). When blood flow is absent in the affected testicle, the diagnosis of testicular torsion is clear. Occasionally decreased blood flow seen in early torsion can be erroneously diagnosed as normal. Thus, comparison to the contralateral side is crucial. Color Doppler alone will not assure both venous and arterial flow in the testicle. Spectral Doppler tracings should also be obtained to confirm both arterial and venous flow. The absence of a venous pattern by spectral Doppler on the affected side suggests early torsion. If the diagnosis is in doubt due to torsion-detorsion, repeat color Doppler imaging along with spectral examination in one hour is recommended. (2,3,4)
EpididymitisEpididymitis is the most common cause of acute scrotal pain in postpubertal males. Classically, patients present with a painful tender scrotum, dysuria, and fever. Retrograde spread of infection from the bladder or prostate is usually the underlying etiology with the head of the epididymis most commonly involved. Gray-scale findings of acute epididymits include an enlarged epididymis with decreased echogenicity. Often, a reactive hydrocele is noted as well (Figure 7). A chronically inflamed epididymis becomes thickened and has focal echogenicity with areas of calcification. With Doppler sonography increased blood flow secondary to epididymal inflammation is noted. The presence of normal or increased blood flow in the affected testicle when compared to the contralateral side differentiates epididymitis from testicular torsion. (2,3,4)
OrchitisOrchitis is an acute infection of the testicle usually following epididymitis. Orchitis often presents with a tender and inflamed testicle. On gray-scale ultrasound, orchitis is seen as an enlarged testicle with heterogeneous echogenicity. This appearance is nonspecific and can be seen in many other conditions such as tumors, metastasis, infarct and torsion. Standard B-mode is not a reliable method to differentiate between orchitis and testicular torsion. For both orchitis and torsion, inflammation and edema can lead to enlargement and heterogeneous echogenicity of the testis. Color Doppler is helpful to differentiate between orchitis and torsion since blood flow in orchitis is increased in comparison with the unaffected side due to inflammation (Figure 8). (2,3,4)
Appendix epididymis. Longitudinal US image shows an appendix epididymis (arrow) projecting from the normal triangular epididymal head (arrowhead). Visualization is aided by the presence of a hydrocele. T testis.
Appendix testis. Longitudinal US image shows a small soft tissue remnant projecting from the superior aspect of the testis (arrow). There is also a moderate-sized hydrocele.
Coronal T2-weighted MR image of the scrotum shows a high-signal-intensity testis within each hemiscrotum. A low-signal-intensity capsule, the tunica albuginea, surrounds each testis. The epididymis (long arrow) is low signal intensity compared with the testis. Also note the small left-sided hydrocele (*), spermatic cord (arrowhead), and varicocele (short arrow).
Hematocele. (a) Longitudinal US scan shows a complex, heterogeneous fluid collection distorting the left testis (T). (b) Photograph of the gross specimen shows the large hematocele (arrow) compressing the normal testicular parenchyma. T testis.
Scrotal abscess with Fournier gangrene. (a) Transverse US image shows a large, complex, heterogeneous fluid collection. It is exerting marked mass effect with displacement and distortion of the testis (arrow). (b) Preoperative photograph shows a tense, swollen scrotum with sloughing and weeping of the dermal tissues.
Scrotal mesothelioma. (a) Transverse US image shows a hydrocele with several soft-tissue nodulesstudding the tunica vaginalis (arrows). (b) Photograph of the resected scrotum demonstrates multiple soft-tissuenodules (arrows).
Scrotal calculi. Longitudinal US image shows a densely calcified free body with posterior acoustic shadowing (arrow). T testis.
Metastatic rhabdomyosarcoma in a 21-year-old man who presented with a palpable scrotal mass.(a) Longitudinal US image of the inferior portion of the right hemiscrotum shows a lobulated soft-tissue mass involvingthe tunica vaginalis (long arrows) and testicular capsule (short arrow). T testis. (b, c) Contrast-enhanced axialCT images show a large, heterogeneously enhancing, right scrotal mass (arrow in b) and retroperitoneal adenopathy(arrows in c). There was also extensive pelvic adenopathy with ureteral obstruction that caused the right-sided hydronephrosisand delayed nephrogram. (d) Photograph of the bivalved scrotal specimen shows a fleshy, tan tumor (arrows)surrounding the testis. Scale is in centimeters.
Leiomyosarcoma. Sagittal T2-weightedMR image shows a large, solid mass of mixed signalintensity filling the left hemiscrotum (arrow). The testis(not shown) was compressed and displaced medially.B bladder, arrowhead prostate.
Polyorchidism. (a, b) Coronal T1- weighted (a) and T2-weighted (b) images show two testes within the right hemiscrotum (arrows). They are slightly smaller than, but identical in signal intensity to, the normal left testis. On both images, all three testes are surrounded by a low-signal-intensity tunica albuginea. (c) Photograph obtained after a right inguinal orchiectomy shows two ovoid testes.
COURSE OF STUDY
A ). NORMAL GROSS ANATOMY
B ). RADIOLOGAICAL ANATOMY
C ). DISORDERS
1. Echogenicity depends on the stage of sexual
2. Testicular echogenicity should be homogenous.
3. It is normal to see a small amount of fluid in the scrotal
4. The epididymis should be evaluated in all its portions.
5. The epididymis should be hypoechoic and discretely
6. Testicular and epididymal vascularity is of low resistance,
quantitative analysis of the resistive index is not the key to
Longitudinal view of testicle with enlarged pampiniform plexus. Also note the thickening of the
surrounding connective tissue secondary to scrotal inflammation after a failed penile implant.
(Courtesy of Beatrice Hoffmann, M.D.)
A slightly oblique view of a testicle with an enlarged hypoechoic epididymis. (Courtesy of
Michael Blaivas, M.D.)
Orchitis. Marked increase in blood flow is seen along with a reactive hydrocele. (Courtesy of
Michael Blaivas, M.D.)