How to Read Mri of Scrotum Ultrasound

Fig. 6.i

Patient is placed in a supine position with a towel placed nether the scrotum

Fig. 6.two

Patient positioning: the phallus is positioned upward on the pubis, held past the patient or a towel

Fig. 6.three

Sonographer performing a longitudinal view of the testis. Note the use of the fifth finger on the patient's thigh to help steady the transducer and minimize movement of the testis in the scrotum

Fig. half-dozen.4

Sonographer positioning the transducer for a transverse view of the testis. Note again, the use of the fifth finger on the patient'southward thigh to help steady the transducer and minimize movement of the testis in the scrotum

Transducer Selection

The choice of the frequency used is adamant past a rest betwixt depth of penetration required and the detail of the image required. As the frequency increases the paradigm resolution (centric resolution) improves and the depth of penetration decreases. Broad bandwidth transducers allow for multiple focal zones, eliminating the need for aligning during the examination. Multiple frequency transducers let the transducer to exist set to several singled-out frequencies. A high frequency (vii–18 MHz) array transducer is most often used for scrotal scanning. A linear array probe with a "footprint" able to mensurate the longitudinal length of testis is ideal. A curved array probe tin can be used with a thickened scrotal wall or in the presence of scrotal edema or for a large testis. The curved array transducer is also useful to compare echogenicity of the testes; notwithstanding, the frequency is usually lower with a curved array probe, resulting in decreased axial resolution. Color and spectral Doppler are essential elements of scrotal ultrasound because they provide documentation of testicular blood flow and paratesticular findings. The highest possible Doppler frequency, typically in the 5–x MHz range providing the all-time centric resolution and blood flow detection, should exist used [1].

Overview of the Test

The American Institute of Ultrasound in Medicine (AIUM) guidelines recommend that scrotal ultrasound should be performed in at least two planes: longitudinal and transverse. In the longitudinal view, the standard orientation of the image should be with the superior pole of the testis to the left and the junior pole to the correct on the monitor screen (Fig. 6.5). In the transverse aeroplane, the standard orientation is for the patient'due south right testis to be the correct side of the screen. Therefore, for the right testis, the lateral aspect is located on the left side of the screen and the medial aspect to the right. Conversely, for the left testis, the lateral aspect should be to the correct and the medial attribute to the left (Fig. 6.6).

Fig. 6.5

Schematic view of longitudinal scrotal ultrasound

Fig. vi.6

Schematic view of transverse scrotal ultrasound as seen on the ultrasound screen with the right testis on the left and left testis on the right. The relative positions of each epididymis is as well demonstrated

The evaluation of the scrotal contents should begin with a longitudinal survey scan, progressing medial to lateral to get an overall impression of the testis and paratesticular structures. If the testis is larger than the footprint of the transducer, it is important to certificate views of the superior and inferior portions of the testis including the epididymis in these regions. The transverse view is obtained by rotating the transducer 90°. A survey scan is performed using the mid-testis as a starting point and proceeding beginning toward the superior pole so back to the mid-testis before scanning to the junior pole.

At least one image should visualize both testes to document the presence of ii testes and their relative echogenicity (Fig. 6.7) [ii]. Measurements of the testicular width and height are taken and documented at the mid-testis. A measurement should also exist made of the long axis at the mid-testis and a testicular volume is calculated (Fig. vi.viii). If the equipment being used has separate-screen capabilities, comparative views of echogenicity can easily exist made and documented.

Fig. 6.seven

Greyness scale side-past-side view of both testes in a single image. This image is of import to confirm the presence of two testes

Fig. 6.viii

Grayness calibration ultrasound in transverse and longitudinal planes used to measure the testicular book

All relevant extratesticular structures should be evaluated, including but not express to the epididymis, spermatic cord, and scrotal skin. Techniques that better visualization, such as Valsalva maneuver or upright positioning, may be used as needed.

Color and Spectral Doppler

Color and spectral Doppler should exist considered an integral part of the scrotal US test. Many inflammatory, neoplastic, and benign conditions have feature flow patterns that can help in diagnosis. At to the lowest degree one side-by-side epitome containing both testes with identical Doppler settings should be included to evaluate symmetry of catamenia. If blood menses cannot be visualized on color Doppler (Fig. 6.9a), power Doppler may increase the sensitivity to detect blood menstruation (Fig. six.9b) [one].

Fig. half dozen.9

(a) Color Doppler Ultrasound demonstrating testicular blood period. (b) Power Doppler Ultrasound demonstrating testicular blood period. Note lack of directionality with Power Doppler

Documentation

The written written report and archived images are a reflection of the quality of the examination. The old aphorism "If it's non documented, information technology wasn't done" should guide the sonographer in developing a quality study. The static images obtained during the evolving ultrasound exam should represent the sonographer's impression of the findings. If electronic storage infinite is available and the equipment allows, video clips, which demonstrate important findings and survey scans, tin and should be obtained. A quality report can assist in diagnosis and is therefore in the best interest of our patients.

All the measurements and anatomical findings of the exam should be documented. Images should exist attached to the report. It is essential to include patient identification information, the exam date, and the indications for performing the exam. The transducer used and its frequency should also be documented. The area of involvement should be conspicuously identified. The orientation and measurements should be labeled along with the pertinent anatomy and any abnormalities. At that place is no minimum number of images that are required for proper documentation. It is a best practice to provide images that depict the measurements being taken and the pathology being described. The physician who performed the exam should sign the report.

Indications

There are many specific indications for scrotal ultrasound (Table six.1 ). Scrotal ultrasound is often performed when the physical examination is inconclusive or difficult to consummate (or both) because of patient discomfort or inability of the examiner to precisely identify the scrotal structures on palpation. In these instances the scrotal ultrasound examination is therefore an integral office of the physical examination of the male genitalia. In other situations, ultrasound evaluation is essential to diagnosis and treatment and is well supported in the literature. Yet, the decision on whether or not to obtain an ultrasound report is discretionary and without a conspicuously divers evidence-based approach [3, 4].

Tabular array 6.i

Indications for scrotal ultrasound

ane. Cess of scrotal mass

(a) Painful enlargement

• Epididymitis/orchitis

• Testicular abscess

• Torsion

(b) Nonpainful enlargement

• Testicular tumor

• Hydrocele

• Varicocele

• Spermatocele/epididymal cyst

• Scrotal hernia

• Cyst

2. Evaluation of scrotal trauma

(a) Testicular rupture

(b) Hematocele

3. Evaluation and management

(a) Detection of occult principal tumors in patients with metastatic germ prison cell tumors

(b) Follow-upwards of patients with prior primary testicular neoplasms, leukemia, or lymphoma

(d) Evaluation of intersex conditions

4. Investigation of empty/abnormal scrotal sac

(a) Undescended testis

(b) Thickened scrotal peel

5. Evaluation of male infertility and related issues

(a) Varicocele

(b) Intratesticular microcirculation

(d) Microlithiasis

(e) Dumb semen quality

(f) Azoospermia

(chiliad) Antisperm antibody

6. Postoperative follow upward

(a) Varicocele

(b) Testis biopsy

(d) Patients with indeterminate scrotal masses

Normal Anatomy of the Testis and Paratesticular Structures

Scrotum

The normal scrotal wall thickness varies between ii and 8 mm. The scrotal wall contains the following structures: rugated skin, superficial fascia, dartos musculus, external spermatic fascia, cremasteric fascia, and internal spermatic fascia. The scrotum is separated into right and left hemiscrotal compartments past a septum termed the median raphe. As the testis descends in utero from the abdomen, it acquires each layer of the scrotal compartment. The external spermatic fascia is derived from the external oblique fascia and is attached to the external inguinal ring. The cremasteric fascia and muscle derive from the internal oblique muscle. Encasing each testis is the tunica vaginalis, derived from the peritoneum, which consists of parietal and visceral layers. These layers are commonly separated by 2–3 mL of straw colored fluid often referred to as a physiologic hydrocele. Ultrasound of this fluid is seen as a sparse echo free rim effectually the caput of the epididymis [5] (Fig. half-dozen.10). The parietal and visceral layers join at the posterolateral aspect of the testes where the tunica attaches to the scrotal wall [six].

Fig. 6.10

Grey scale ultrasound showing physiologic hydrocele (arrow)

Testis

The size and shape of the testis changes with the age, influenced past gonadotropic hormones testicular book gradually rises from birth to up to 5 months of age due to peak in gonadotropic hormones levels [7, 8]. After 5 months of age, the testicular volume steadily declines and reaches its minimum volume at approximately ix months of age and remains approximately the same size until puberty [9]. In newborns, the testis is round and gradually becomes ovoid with growth. The echogenicity of the testis increases in puberty due to the development of germ cell elements [10]. The developed testis is a smooth ovoid gland, approximately four–5 cm long, iii cm broad, 2–3 cm in the anterior–posterior (AP) dimension, and typically between twenty and 30 mL in book .

The testis exhibits medium homogenous echogenicity. A dense fibrous sheathing the tunica albuginea envelops the testis, which is apparent as a sparse echogenic line on ultrasound. Each testis has approximately 200–300 cone-shaped lobules each containing at to the lowest degree one seminiferous tubule [11] (Fig. six.eleven). The lobules are separated by the fibrous septa of tunica albuginea that extend from the mediastinum of the testis in to the parenchyma of the testis [12]. Testicular lobules are occasionally identified on ultrasound as lines radiating from the mediastinum testis (Fig. half dozen.12). The seminiferous tubules contained within the lobules open into dilated spaces called rete testis within the mediastinum. The seminiferous tubules are long V-shaped tubules, both ends of which usually cease in the rete testis. The rete testis is continued to the head (caput or globus major) of the epididymis with about 8–12 efferent ductules. The normal rete testis is sonographically axiomatic in 18 % of patients as a hypoechoic area with a striated configuration adjacent to the mediastinum testes [xiii]. The mediastinum testes appear as a linear avascular echogenic band on ultrasonography [14] (Fig. half dozen.thirteen).

Fig. 6.11

Schematic cross section of the testis

Fig. vi.12

Gray scale ultrasound of a normal testis demonstrating testicular lobules separated past gristly septa (arrows)

Fig. 6.13

The mediastinum testis appears equally an avascular echogenic line (arrow)

Epididymis

The adult epididymis is 6–7 cm long and has three parts, the head (head) measuring ten–12 mm in diameter, the body (corpus) measuring 2–4 mm in bore, and the tail (cauda) about 2–5 mm in bore. In the normal epididymis, the head is routinely identified at posterolateral to the upper pole of the testis. The head epididymis is triangular in shape, often has the same echogenicity every bit the testis (Fig. 6.xiv). Nevertheless, information technology tin can be heterogenous with areas that are hyper or hypoechogenic. The smaller corpus epididymis can be seen as a hypoechoic structure containing multiple echogenic linear structures representing the coiled epididymal tubule and lies posteriorly along the long centrality of the testis (Fig. 6.15).

Fig. 6.fourteen

The caput epididymis is triangular in shape (East) and is unremarkably isoechoic or slightly hypoechoic compared to the testis

Fig. vi.xv

Grayness scale paradigm of a dilated corpus epididymis in a vasectomized homo

Vascular Beefcake

The spermatic string is normally seen superior to the posteromedial aspect of the testis and contains the vas deferens, the testicular and cremasteric and deferential arteries, the pampiniform plexus of veins, genital co-operative of the genital femoral nerve, testicular plexus of the sympathetic trunk, and lymphatic vessels [12]. The blood supply to the scrotal structures is from three primary arteries: the testicular, deferential, and cremasteric arteries (Fig. 6.16). The testicular artery testis or gonadal artery, which arises from the aorta and courses through the scrotum with the spermatic cord, is the major supply to the testis. The deferential artery, which arises from the superior vesical avenue and supplies the vas deferens and epididymis. The cremasteric avenue, a branch of the inferior epigastric artery, which supplies the scrotal skin and coverings of the spermatic cord. As the testicular artery approaches the posterolateral aspect of the testis it divides. The branches pierce through the tunica albuginea to run in a layer called the tunica vasculosa. Capsular arteries run peripherally in the tunica vasculosa, supplying centripetal arteries that grade toward the mediastinum and divide further to recurrent rami that flow away from the mediastinum [14]. The veins draining the testis and epididymis converge to grade the pampiniform plexus at the mediastinum on the superior pole of the testis. The pampiniform plexus is primarily drained by the testicular and external pudendal veins [15]. The testicular vein on the left drains into the renal vein and the testicular vein on the right directly into the inferior vena cava [xvi].

Fig. 6.xvi

Blood supply of testis . The testis is supplied by iii sources of blood supply. (one) The testicular artery, which arises from the aorta. (2) The deferential avenue, which arises from the superior vesical artery. (iii) The cremasteric avenue, a branch of the inferior epigastric avenue

Ultrasonography with Color-Catamenia imaging provides visualization of the intratesticular, epididymal, and paratesticular blood flow. Under normal conditions, Color Flow images bear witness equivalent vascularity of the bilateral testis. When vascularity is not well visualized, Power Doppler increases the sensitivity of detection. Spectral Doppler is used to summate the Resistive Index (RI) of intratesticular arteries. The RI of intratesticular arteries has been constitute to correlate with testicular function .

Embryology Relevant to Ultrasound Imaging of the Scrotum

A basic understanding of the embryologic development male person gonad and adnexal structures guide the interpretation of many abnormalities encountered in the scrotal ultrasound. Presented in this section is the embryology relevant to the ultrasound evaluation of the scrotum. There are many first-class textbooks bachelor which nowadays the known elements of male genitourinary development should the reader desire a more comprehensive treatise on the subject [17–twenty].

Early Gonadal Developmental Anatomy

In the 3-week-sometime embryo (Fig. 6.17), primordial germ cells, originating in the wall of the yolk sac most the attachment of the allantois, migrate along the wall of the hindgut and through the dorsal mesentery into the urogenital ridge. The urogenital ridge is a protrusion of intermediate mesoderm that indents the coelomic cavity (forerunner to the peritoneal crenel) on each side of the mesentery. The kidney precursors, gonads, and the proximal portions of the reproductive tracts develop from the urogenital ridge. The unilateral absenteeism of the male reproductive ducts or gonad and reproductive ducts is associated with ipsilateral absence of the kidney in 20–85 % of cases [21]. It is therefore reasonable to evaluate the retroperitoneum for the presence of a kidney in a patient where the unilateral reproductive ducts are absent on ultrasound evaluation.

Fig. half-dozen.17

Primordial germ cells at their location in yolk sac as they begin their migration (a). The primordial germ cells migrating through the mesentery to the genital portion of the urogenital ridge bulging into the coelomic crenel (b)

In the 5-calendar week-quondam embryo (Fig. 6.xviii), the two early excretory organ systems (the pronephros and mesonephros ) begin to backslide. The mesonephros constitutes the lateral portion of the urogenital ridge and consists of mesonephric tubules that interact with glomeruli-similar vessels extending from the aorta at one terminate and bleed into a mesonephric duct at the other finish. The regression begins at the cranial aspects and continues toward the caudal terminate where the duct joins the cloaca (and at what will somewhen diverge from the cloaca into the urogenital sinus). The ureteric bud (also referred to as the metanephric diverticulum) develops as a dorsal bud of the mesonephric duct near its insertion into the cloaca. The metanephros (precursor to the developed kidney) forms from the interaction of the metanephric diverticulum and a region of cells in the intermediate mesoderm known equally the metanephric jail cell mass.

Fig. 6.18

Development of the early on excretory system. Regression of the pronephros (a) and mesonephros (b) with the evolution of the metanephric system

At 7 weeks (Fig. 6.xix), the reproductive ducts of embryo remain devoid of phenotypic manifestations of sexual differentiation. In that location are two, roughly parallel pairs of genital ducts: in addition to the mesonephric (Wolffian) ducts at that place are the paramesonephric (Müllerian) ducts, which are located more laterally. Forth the medial portion of the urogenital ridge, cords of coelomic epithelium termed sexual practice cords have invaginated in to the ridge and house the primordial germ cells. This portion of the urogenital ridge becomes the gonadal ridge and the most superficial aspects of the sex cords regress to completely separate the sex cords from the residuum of the coelomic epithelium.

Fig. six.19

The reproductive ducts and their relationship to the developing gonads later on the incorporation of the distal mesonephric ducts into the urogenital sinus

It is the presence of a Y chromosome factor, called the sex-determining region Y factor (SRY ), that results in the evolution of testes and the initiation of phenotypic sexual differentiation. The testis forms in the gonadal ridge and Sertoli cells differentiate from cells within the epithelial sex cords. By week 8, the developing fetal testis produces at least two hormones. The outset has been referred to equally Müllerian-inhibiting substance or factor (MIS, MIF) and, in other reports, every bit anti-Müllerian hormone (AMH). It is produced past the fetal Sertoli cells and suppresses the development of the paramesonephric duct (which in the absenteeism of this suppression would develop into the upper female reproductive tract organs). The other, testosterone, stimulates evolution of the mesonephric ducts into components of the male person genital tract. Vestigial remnants of portions of these ducts (Fig. 6.20) often can be visualized sonographically.

Fig. six.20

Schematic showing the most frequent location of testicular and epididymal appendages and other vestigial remnants of the mesonephric and paramesonephric ducts in the male genitalia

Remnants of the nearly cranial aspects of the regressed paramesonephric ducts can persist across the embryologic period as the appendix of the testis in and exist demonstrated on ultrasound (Fig. 6.21). The most caudal vestiges of the paramesonephric ducts form midline structures and are ofttimes found in the prostate, which is derived from the embryonic urogenital sinus. The prostatic utricle is such a structure and when enlarged, be demonstrated on ultrasound. In addition, midline cysts derived from vestiges of the paramesonephric ducts may also exist demonstrated. These midline paramesonephric remnants have too been found to obstruct the ejaculatory ducts and outcome in dilation of the seminal vesicles (anterior–posterior distance greater than 15 mm).

Fig. six.21

Ultrasonic appearance of the appendix testis

The deepest aspects of the sex activity cords converge on what will become the mediastinum testis. The mesenchyme between each of the cords gives rise to the interstitial cells of Leydig and the septa of the testis that radiate out from the mediastinum testis. The sex cords develop into tubules composted of the germ cells and Sertoli cells and the inner ends of these tubes are referred to as the tubuli recti. The gonadal ridge, throughout its development, slowly separates from the mesonephros. The mesonephric structures develop under the paracrine influence of the testosterone produced in the neighboring testis. The mesonephric tubules side by side to the testis develop into the ductuli efferentia and encounter the tubuli recti at the rete testis. The mesonephric ducts develop into the epididymides, vasa deferentia, and ejaculatory ducts. The seminal vesicles develop as a diverticulum of this tube. Residual mesonephric structures can persist equally a vestigial remnant of the mesonephric ducts. Those tubules located cranial to the tubules that become the ductuli efferentia of the testis may protrude off the epididymis as a polypoid vestige called the appendix epididymis (Fig. 6.22). In addition, remnant mesonephric tubules can persist proximal to those draining the testicle as well. This remnant is known as the paradidymis (aka organ of Giraldés), a small collection of convoluted tubules lined by ciliated epithelium, that can be institute anywhere along the epididymis or vas deferens.

Fig. 6.22

Ultrasonic image of the head epididymis with next appendix epididymis

Torsion of the appendix testis, appendix epididymis, and paradidymis are all in the differential diagnosis of the acute scrotum . The appendix testis, appendix epididymis, and ectasia of the rete tubules can be visualized during the scrotal ultrasound and their feature appearance should be kept in heed to avoid confusion of these structures with testicular and extratesticular masses.

Testicular Descent

The process of testicular descent begins prior to seven or 8 weeks in development. At this fourth dimension, the gonadal position in the dorsal intestinal wall is similar in both sexes. In males, the fetal testis begins to produce MIS from the Sertoli cells. In addition, androgens and an insulin-like hormone 3 (INSL3) are produced from the Leydig cells [22]. These hormones work in concert to control descent of the testis, which is held by a suspensory ligament at the upper pole, and, at the lower pole by the genito-inguinal ligament, or "gubernaculum."

During the initial phase of descent, the cranial suspensory ligament progresses and the gubernaculum thickens allowing the testis to exist held near the inguinal region as the abdomen enlarges. The inguinal culvert forms every bit the intestinal wall muscles develop around the thickened gubernaculum.

The subsequent phase of descent occurs several weeks later. At nigh 20–25 weeks an out-pouching of the peritoneal membrane, which is known as the processus vaginalis, travels with the testis toward its concluding position in the scrotum. The processus vaginalis maintains a connection with both the epididymal tail and the lower pole of the testis. At about 25 weeks, testis and attached processus vaginalis brainstorm to pass through the inguinal canal along with fascial coverings from the abdominal wall (Fig. 6.23). The processus vaginalis is continuous with the peritoneum and tunica vaginalis of the testis. Between 25 and 30 weeks the testis descends rapidly through the inguinal canal and then more slowly across the pubis into the scrotum. The fascial coverings from the intestinal wall that travel with the testis during its descent become the layers covering the spermatic cord and testis. This procedure is usually completed by 35 weeks of gestation and information technology is followed by the obliteration of the proximal portion of the processus vaginalis to close the connection between the scrotum and peritoneum. Closure may occur during prenatal development or in early infancy. The gubernaculum does not become anchored to the scrotum until descent is completed [23–25].

Fig. 6.23

The phases of testicular descent . At almost 25 weeks, testis and attached processus vaginalis begin to pass through the inguinal canal along with fascial coverings from the abdominal wall

The embryology of testicular descent becomes important for the sonographer when evaluating the undescended or nonpalpable testis. A bulk of undescended testes are establish in the inguinal culvert which is accessible to diagnostic ultrasound [26–29]. Ultrasound examination of the inguinal region is essential when a testis is not constitute on routine scrotal ultrasound .

Development of the Scrotum

The embryonic precursor to the scrotum is the labioscrotal folds. These structures originate every bit the embryonic cloaca develops and differentiates. The cloaca is a chamber shared by the allantois (which extends anteriorly from the cloaca into the umbilical cord) and the hindgut (Fig. vi.18a). The cloacal membrane makes up the ventral wall of the chamber and is located at the caudal stop of the developing hindgut as a bilaminar apposition of ectoderm and endoderm located on the ventral midline. A septum develops as an ingrowth of folds from the lateral walls and a caudal extension of the intervening mesenchyme from the branch point of the allantois and hindgut, which ultimately divides the cloaca into the anterior/ventral urogenital sinus and the posterior/dorsal developing rectum. While the septum develops, mesodermal mesenchyme likewise encroaches between the ii layers of the cloacal membrane. The septum also divides the membrane into a urogenital membrane and anal membrane. Both of these membranes ultimately rupture to create continuity betwixt the ectoderm and both the urogenital sinus and rectum that volition persist equally the urethral meatus and anus. The mesenchymal tissues that have encroached effectually these orifices develop into the muscles and basic of the lower anterior abdomen and pubis.

The urethra prostate and float all develop from the urogenital sinus . The remnants of the caudal ends of the mesonephric ducts go incorporated into the urogenital sinus (Mullerian Tubercle, Fig. 6.19) and become aspects of the trigone and posterior urethra. The incorporated portions of the mesonephric ducts include the branch points of the metanephric ducts, which become the ureteral orifices. The unincorporated portions of the mesonephric ducts end up entering the urethra at the prostatic urethra as the ejaculatory ducts which channel the path of the testicular adnexal structures into the prostatic urethra.

The external male ballocks are indistinguishable from the female external genitalia until the eighth or 9th week of gestational. They both include the genital tubercles at the craniolateral edges of the cloacal membrane. The tubercles develop from mesoderm equally it infiltrates the cloacal membrane. Every bit the cloacal membrane divides to separate its inductive portion into the urogenital membrane, the tubercles fuse in the midline. The urogenital membranes and ultimately the urogenital sinus are flanked by collections of infiltrating mesoderm termed the urogenital folds with labioscrotal swellings located laterally on either side (Fig. half-dozen.24). Masculinization of the indifferent external genitalia occurs under the endocrine influence of testosterone produced past the interstial Leydig cells of the fetal testis [xxx–32]. The tubercle becomes the future phallus and glans. The scrotum is formed by extension of the labioscrotal swellings between the pelvic portion and the anus. With testicular decent and migration of the gubernaculum into these labioscrotal swellings during the second stage of testicular descent, the scrotal sac takes shape around the testes and associated structures. The scrotal skin volition ultimately get the indicate of contact with the ultrasonographer'south transducer and the window into which clinical questions well-nigh the scrotal contents can exist explored.

Fig. 6.24

The male external genital development progressing clockwise from the left. The genital tubercle develops into the glans penis. The upper correct panel shows the urogenital sinus opening within the urogenital folds, which are between the scrotal swellings

Pathologic Conditions and the Scrotal Ultrasound

Extratesticular Findings

Hydrocele

Hydrocele is the most mutual crusade of painless scrotal swelling. A hydrocele is a serous fluid drove between the parietal and visceral layers of the tunica vaginalis. The tunica vaginalis is a mesothelium-lined sac that results from closure of the superior portion of the processus vaginalis. This fascial construction commonly covers the entire testis except the posterior border. It has a visceral layer and an outer parietal layer that lines the internal spermatic fascia of the scrotal wall. Hydroceles can be congenital or caused. The congenital hydrocele or communicating hydrocele occurs when a patent processus vaginalis allows fluid to pass from the peritoneal infinite into the scrotum [33]. The acquired hydrocele may be idiopathic with no identifiable crusade. The incidence of hydroceles is about 1 % of adult males. Hydroceles are usually anechoic on ultrasonography (Fig. 6.25). They may contain echogenic cholesterol crystals. The presence of septations is frequently associated with infection, trauma, or metastatic disease. Hydrocele may develop secondary to venous or lymphatic obstacle caused by infection, trauma, torsion, or tumor. Nearly 10 % of testicular tumors are accompanied by a hydrocele; clinical suspicion increases with new onset of hydrocele in men in their 30s or 40s [34]. Scrotal ultrasound is essential to rule out testicular pathology in these patients. The testis is often posteriorly displaced by the hydrocele. A massive hydrocele exerts a force per unit area effect that may compromise blood flow within the testis. Vascular resistance in intratesticular arteries is increased, and color Doppler ultrasound may demonstrate an increase in the caliber of capsular arteries. Fluid aspiration and surgical excision of hydrocele sac has been shown to restore normal claret menses to the testis [35].

Fig. half dozen.25

Gray scale ultrasound showing a left hydrocele (H)

Pyocele

Pyocele is an accumulation of purulent cloth inside the tunica vaginalis and is well-nigh often occurring because of untreated epididymo-orchitis. Pyoceles nowadays with acute scrotal pain and symptoms of sepsis. A pyocele too appears heterogeneous on the ultrasonogram, and gas may be identified, causing hyperechoic reflections and shadowing [36] (Fig. 6.26).

Fig. 6.26

A pyocele is seen as a complex heterogeneous fluid collection within the tunica vaginalis on grey calibration ultrasound and without claret menstruum on Doppler study

Scrotal Hernia

Congenital inguinal hernia is due to failure of the processus vaginalis to obliterate and result in passage of intestinal loops or omentum or peritoneal fluid in the scrotal sac [12, 37, 38]. Correct inguinal hernias are more mutual as the right processus vaginalis closes later. Scrotal ultrasound tin be helpful for inconclusive physical examination. Clinically occult contralateral hernia can also exist assessed with the ultrasound [39]. Patients with a scrotal hernia normally present with mesenteric fat and/or bowel loops seen superior to the testis. Real-time imaging tin can identify peristaltic action or intestinal gas bubbling with their characteristic echogenic interfaces. Ultrasound of an omental hernia will demonstrate highly echogenic fat [40] (Figs. half dozen.27a, b and 6.28).

Fig. 6.27

(a) Grayness scale ultrasound showing the highly echogenic omental fat of an omental hernia. (b) Color Doppler study showing no increased claret menstruation to the inguinal hernia

Fig. 6.28

Gray scale ultrasound showing thickened hernia sac (W) in chronic inguinal hernia (arrows)

Sperm Granuloma

Spermatazoa are highly antigenic, and an intense inflammatory reaction occurs when they go out the vas difference [twoscore]. Sperm granulomas occur in at to the lowest degree xl % of men following a vasectomy [41] (Fig. 6.29). Sperm granulomas are rarely symptomatic. However, ii–iii % of vasectomy patients will have pain attributed to sperm granulomas, usually occurring 2–3 weeks postoperatively [42].

Fig. half dozen.29

Gray scale ultrasound showing a sperm granuloma (red pointer)

Tumors of the Spermatic Cord

Lipomas of the spermatic cord are very common benign lesions of the spermatic card. They can be unilateral or bilateral, and often present equally asymptomatic fullness of the spermatic string. Ultrasound of a lipoma demonstrates homogeneous echogenicity similar to subcutaneous fatty without internal color flow. The echogenicity of lipomas may be variable, and MRI may be helpful to confirm diagnosis, showing nonenhancing, fat saturated areas [43]. It is also important to differentiate a lipoma from an inguinal hernia by noting the intact external inguinal ring on physical examination and assessing for the presence of a hernia on ultrasound.

Rhabdomyosarcomas of the spermatic string is a malignant lesion in children, and liposarcoma is the virtually common malignant tumor arising in the spermatic cord in adults, although both are rare. Leiomyosarcomas in the paratesticular space too have been reported. The ultrasound appearance of these lesions is an ill-divers solid mass with heterogeneous echotexture and increased vascular flow on Doppler color report (Fig. half dozen.30).

Fig. 6.30

Leiomyosarcoma of the scrotum: (a) Gray scale ultrasound appearance equally an ill-defined solid mass with heterogeneous echotexture in the paratesticular space (G mass, T Testis). (b) Doppler colour flow shows increased vascularity with in the mass

Epididymal Findings

Epididymo-Orchitis

Epididymitis is the most common cause of subacute unilateral scrotal pain in preadolescent and adolescent boys and developed men. On concrete exam the epididymis tin often be identified every bit an enlarged and tender structure posterolateral to the testis. The hurting is often relieved with elevation of the testis over the symphysis pubis, known as Prehn's sign. Among sexually active men younger than 35 years old, epididymitis oft results from sexually transmitted infections, particularly Chlamydia trachomatis and Neisseria gonorrhoeae. In older men, bacterial epididymitis can outcome from retrograde transit of leaner from the vasa, and therefore the nigh common organisms are urinary pathogens: Escherichia coli and Proteus mirabilis. Rare infectious causes include brucellosis, tuberculosis, cryptococcus, syphilis, and mumps. Epididymitis in prepubertal boys normally has a benign grade, and these boys commonly are found to have positive titers for enteroviruses and adenoviruses and M. pneumonia. Rare noninfectious causes include sarcoidosis and amiodarone. Edgeless trauma every bit well every bit congestion following vasectomy is potential cause of epididymal inflammation [44, 45].

In patients with acute epididymitis, the epididymis is enlarged with increased vascularity. Epididymitis may lead to focally or global enlargement and thickening of the epididymis. Gray scale ultrasound demonstrates a hypoechoic or heterogeneous enlarged epididymis (Fig. 6.31). The color flow Doppler shows increased vascularity with loftier-flow, depression-resistance pattern (Fig. six.32). A reactive hydrocele is often present. Complications of epididymitis include infectious spread to the testis resulting in epididymo-orchitis, testicular abscess formation, and testicular infarction due to obstruction of venous flow which may result in testicular atrophy. Patients with chronic epididymitis often nowadays with persistent pain. In these men, ultrasound examination reveals an enlarged epididymis with increased echogenicity and possible areas of calcifications (Fig. 6.33).

Fig. 6.31

Epididymo-orchitis : gray scale image demonstrates enlarged and heterogeneous epididymis and testis

Fig. 6.32

Epididymo-orchitis : Power Doppler ultrasound showing increased vascularity of the epididymis and the testis

Fig. six.33

Chronic epididymitis : Greyness scale ultrasound showing increase of echogenicity and microcalcifications seen in the caput epididymis (arrows)

Torsion of the Appendix Epididymis and Testis

Torsion of the appendix testis is of import to differentiate from torsion of the spermatic cord (testicular torsion), every bit this condition is cocky-limiting and does not threaten testicular viability. Clinically, the cremasteric reflex is preserved and a palpable nodule with bluish discoloration (blue dot) is ofttimes detected [46]. Ultrasound shows a hyperechoic mass with primal hypoechoic area side by side to the testis or epididymis. Other associated findings include scrotal wall edema and epididymal enlargement. Blood menses in the peritesticular structures may be increased. Doppler ultrasound is helpful as claret flow within the testis is normal in torsion of the appendix testis.

Benign Epididymal Lesions

An epidydimal cyst is a nonpainful cystic structure that, when big, displaces the testis inferiorly. Cysts of the epididymis occur in upwards to 40 % of the men and contain lymphatic fluid. They are typically thin walled and well defined, usually with strong posterior audio-visual enhancement and no internal echoes. These men will often have multiple cysts occurring nowadays throughout the length of the epididymis.

Spermatoceles are benign cystic lesions, which contain spermatozoa, lymphocytes, and droppings. Spermatoceles form as a issue of efferent duct obstruction and unremarkably located in the caput of the epididymis. Ultrasonography cannot differentiate between epididymal cysts and spermatocele, just the spermatocele often has septations (Fig. half dozen.34).

Fig. 6.34

Gray calibration ultrasound showing multiple anechoic epididymal cysts

Adenomatoid tumors are the most common tumors of the paratesticular tissues, accounting 30 % of these lesions and up to 77 % of the benign tumors arising from the epididymis. They are most unremarkably identified in men in their 20s to 40s. Information technology has been suggested that they derive from vascular endothelium, the mesonephros, or müllerian epithelium, although most recent reports consider them to be mesothelial in origin [47]. They are round, firm, smooth, detached masses measuring 0.5–5 cm in diameter that are unremarkably asymptomatic and wearisome growing. Ultrasonography can ostend the extratesticular nature of these masses. Ultrasound of adenomatoid tumors reveals an isoechoic mass with increased vascularity (Fig. half-dozen.35).

Fig. 6.35

Adenomatoid tumor seen on Grey scale imaging as an as isoechoic paratesticular mass

Papillary cystadenoma is a rare benign tumor of epithelial origin believed to arise from the efferent ductules of the head of the epididymis [48]. Papillary cystadenoma presents clinically as a business firm, nontender palpable mass in the epididymis. Two-thirds of papillary cystadenomas occur in patients with von Hippel-Lindau (VHL) syndrome and are frequently bilateral [49]. Unilateral presentation is seen very rarely in desultory cases. Sonographically, small papillary cystadenoma are usually solid and echogenic, only when large may appear vascular and cystic [49].

Leiomyomas are benign epididymal solid tumors. These lesions are most usually seen in men over the age of l. The ultrasound appearance is a well-defined solid mass with heterogeneous echotexture located in paratesticular space carve up from the epididymis [50].

Malignant Epididymal Lesions

Malignant tumors arising from the epididymis are very rare, with the exact incidence of cancerous tumors of the epididymis uncertain considering of the small number of reported cases. Sarcoma of the epididymis comprises of more than than half of the reported malignant neoplasms of the epididymis [51]. Fibrosarcoma of the epididymis has been reported in isolated case reports. Dowling et al. reported fibrosarcoma in a 60-twelvemonth-one-time male confined to the epididymis on final pathology [52]. Leiomyosarcoma of the epididymis on ultrasound appears every bit a large hypoechoic mass (Fig. 6.36). Clear Cell carcinoma of the Epididymis is very rare and has been reported in individual case reports [53]. Ultrasound findings may include large cysts, necrosis, and invasive margins.

Fig. 6.36

Leiomyosarcoma of the epididymis. Gray scale ultrasound showing large hypoechoic mass in the epididymis with normal testis

Scrotal Wall Lesions

Scrotal Infectious Findings

Patients who are diabetic or immunocompromised are more susceptible to infection and scrotal wall cellulitis or abscess. Ultrasonography demonstrates thickening of the subcutaneous tissue and heterogeneity with increased blood flow on colour Doppler study. The scrotal wall abscess appears on ultrasound equally a well-divers hypoechoic lesion inside the scrotal wall and no Doppler flow inside the lesion [5].

Fournier'south gangrene is a polymicrobial rapidly progressing necrotizing fasciitis commonly involves perineum and genital regions. Fournier'southward gangrene is a urologic emergency with mortality upwards to 50 % [54, 55]. Computer tomography remains the imaging modality of choice [56]. However, ultrasonography tin provide valuable clues at the time of initial presentation. Ultrasonography shows marked thickening of the scrotal skin with multiple hyperechogenic foci associated with shadowing, which are consistent with the presence of subcutaneous gas, pathognomonic of Fournier'south gangrene [57].

Benign Scrotal Lesions

Epidermoid Cysts of the Scrotal Wall

Epidermoid cysts or epidermal inclusion cysts are the almost common cutaneous cysts of the scrotal wall. Epidermoid cysts result from the proliferation of epidermal cells within a circumscribed space of the dermis at the infundibulum of the hair follicle [58]. Epidermoid cysts may get infected and course scrotal wall abscess.

Henoch–Schonlein purpura (HSP ) is a systemic vasculitis of unknown origin. It is characterized past a palpable peel rash, abdominal hurting, and polyarthralgia. HSP has been reported to have scrotal wall swelling and ecchymosis in up to 38 % of cases [59].

Scrotal gristly pseudotumors are uncommon and are thought to exist reactive, benign lesions. The sonographic advent of the fibrous pseudotumor of the scrotum is variable depending on the contributing fibrous tissue components, presence or absence of calcification, and the scrotal construction involved [sixty]. Pseudotumor of the scrotum is a benign status and local excision of the mass is the treatment of option; withal, preoperative diagnosis is seldom made due to the nonspecific clinical and sonographic findings [61].

Acute idiopathic scrotal edema (AISE) is a self-express disease of unknown origin. It presents with unilateral or bilateral scrotal swelling without pain and is associated with unilateral or bilateral inguinal lymphadenopathy. It is thought to exist a variant of angioneurotic edema, often associated with eosinophilia. Physical examination findings include scrotal skin swelling and erythema that extends to the inguinal and perianal area. AISE is a diagnosis of exclusion. The characteristic ultrasound findings for AISE, include edema of the scrotal wall with hypervascularity and compressibility with enlargement of the inguinal lymph nodes, and normal testis and epididymis (Fig. half-dozen.37) [62, 63].

Fig. six.37

Greyness scale ultrasound showing diffuse scrotal wall thickening in a patient with scrotal wall edema

The other noninflammatory causes of scrotal wall edema including congestive center failure, renal failure, anasarca, hepatic failure, cirrhosis, nephrotic syndrome, and poor nutritional status. The scrotal wall appears thickened in chronic venous or lymphatic obstruction secondary to filariasis, radiation, and trauma or surgery. Ultrasound demonstrates scrotal wall thickness with layers of alternating hypo and hyperechogenicity [64, 65].

Malignant Scrotal Lesions

Squamous cell carcinoma (SCC ) of the scrotum is an uncommon neoplasm. SCC is associated with occupational exposure to chemical or oil industries, radiation, chimney sweepers, human papilloma virus, chronic scar, and immune-related conditions such as psoriasis [66]. The literature concerning scrotal SCC is limited. Ultrasound evaluation of these lesions is non well defined.

Testicular Pathology

Nonmalignant Abnormalities of the Testis

Torsion of the Spermatic Cord or Testicular Torsion

Ultrasound is ofttimes used to assess boys and adolescents with acute scrotal pain when the urologist is concerned for testicular torsion. Testicular torsion can be classified as extravaginal or intravaginal. The extravaginal grade of torsion is establish exclusively in newborn infants. Intravaginal torsion is more mutual and is due to a bong-and-clapper deformity in which the tunica vaginalis has an abnormally loftier insertion on the spermatic cord and completely encircles the testis, leaving the testis free to rotate within the tunica vaginalis. The deformity is bilateral in nearly cases. Intravaginal testicular torsion occurs most ofttimes in adolescent boys, with two-thirds of cases occurring between 12 and 18 years of age. Intravaginal torsion may occur in testes that are retractile or are not fully descended. Edgeless trauma, sudden forceful rotation of the body, or sudden exertion too predispose to testicular torsion.

Ultrasound is very constructive in differentiating testicular torsion from other causes of acute scrotal hurting. The severity of torsion of the testis can range from 180° to 720°, only complete apoplexy of blood menstruum is thought to occur after 450° of torsion [12]. Transient or intermittent torsion with spontaneous resolution sometimes occurs. Venous congestion or occlusion progresses to arterial occlusion, testicular ischemia, and infarction. The collateral blood menstruation is typically not adequate to provide viability to the testicle if the testicular avenue is occluded. There is a 90 % take a chance of salvaging the testicle when ischemia has been present for less than 6 h, which decreases to 50 % at 12 h and 10 % at 24 h [67]. While irreversible testicular damage is presumed after four h of torsion, only 50 % of men who were detorsed less than 4 h subsequently their symptoms began were noted to have normal semen quality [68].

On gray scale ultrasound, the affected testis usually appears hypoechoic (Fig. 6.38a) and Doppler colour flow written report shows decreased or no menstruation in the affected testis (Fig. six.38b). Testicular size tin can vary from increased to decreased when compared to its counterpart depends upon the duration of the torsion. The sonographer should always compare the affected testis with the contralateral side using longitudinal, transverse, and coronal views. When the sonographer attempts to marshal the transducer parallel to catamenia, upmost views can be peculiarly informative. In patients with astute torsion, the epididymis may appear hypoechoic and enlarged, similar to epididymitis. With testicular torsion ultrasound may also demonstrate that the spermatic string immediately cranial to the testis and epididymis is twisted, which gives it a feature 'torsion knot' or 'whirlpool appearance ' (Fig. half-dozen.39a, b).

Fig. 6.38

(a) Correct testicular torsion with normal left testis for comparing. The torsed testis has decreased echogenicity on gray scale ultrasonogram compared to the contralateral salubrious testis. (b) Color Doppler ultrasound shows absent blood flow in the left testis with testicular torsion and normal period in the good for you right testis

Fig. 6.39

(a, b) The spermatic cord immediately cranial to the testis and epididymis is twisted, which gives it a characteristic 'torsion knot' or 'whirlpool appearance' on gray scale ultrasound

Acute unilateral scrotal pain may be of a nonemergent etiology, due to epididymitis or torsion of a testicular or epididymal bagginess. Waldert et al. retrospectively reviewed the charts of 298 boys who presented with an acute scrotum and underwent color Doppler ultrasonography followed by exploratory surgery, regardless of the sonographic findings. Xx percent were diagnosed with testicular torsion, 56 % with torsion of an appendage, eight % with epididymitis, and 11 % with no definite diagnosis. Color Doppler sonography sensitivity, specificity, positive predictive value, and negative predictive value for testicular torsion were 96.viii %, 97.9 %, 92.i %, and 99.1 %, respectively. The two boys in this study misdiagnosed as epididymo-orchitis were both constitute to have 90° of torsion and no venous drainage only with rest arterial flow [69].

Despite the findings that colour Doppler sonography has a high sensitivity and specificity, it is our feeling that torsion remains a clinical diagnosis proven but at surgery. Ultrasound should only be used to document findings. Many conditions including torsion–detorsion, intermittent torsion, persistent capsular flow, and color flow artifacts tin advise apparent flow in cases where none exists. Therefore, ultrasound does not diagnose or "rule out" torsion, only surgical exploration is indicated when the diagnosis of testicular torsion is suspected.

Primary Orchitis and Testicular Abscess

The ultrasound findings of patients with orchitis are frequently an enlarged testis with homogenous appearance. Orchitis may be diffuse or focal, with focal orchitis appearing as multiple hypoechoic lesions with increased testicular blood flow (Fig. 6.40a, b). Additionally, the RI of the epididymal and testicular artery has been shown to be significantly lower in patients with epididymo-orchitis than in control subjects [70]. If inflammation progresses, the pressure of intratesticular edema may compromise blood menstruum leading to infarction; the ultrasound will demonstrate absenteeism of claret menstruum and surrounding reactive hyperemia [71].

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