G e n i t o u r i n a r y I m a g i n g • R ev i ew Nicola et al. Scrotal and Penile Trauma
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Genitourinary Imaging Review
Refky Nicola1 Nancy Carson Vikram S. Dogra Nicola R, Carson N, Dogra VS
Imaging of Traumatic Injuries to the Scrotum and Penis OBJECTIVE. The purpose of this article is to review scrotal and penile anatomy, the role of ultrasound in evaluating scrotal and penile trauma, and the vast spectrum of sonographic manifestations of scrotal and penile trauma. CONCLUSION. Scrotal and penile trauma is an uncommon type of trauma injury. However, knowledge of scrotal and penile anatomy and the appropriate imaging findings associated with acute traumatic injuries is important in establishing the correct diagnosis. Sonography is considered the first choice of imaging modalities in establishing a diagnosis and triaging patients into surgical and nonsurgical treatment.
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Keywords: Doppler, penis, scrotum, testis, trauma, ultrasound DOI:10.2214/AJR.13.11676 Received August 5, 2013; accepted after revision September 20, 2013. Presented at the 2013 annual meeting of the ARRS, Washington DC. 1
All authors: Department of Radiology, University of Rochester Medical Center, 601 Elmwood Ave, PO Box 648, Rochester, NY 14642. Address correspondence to V. S. Dogra ([email protected]).
This article is available for credit. WEB This is a web exclusive article. AJR 2014; 202:W512–W520 0361–803X/14/2026–W512 © American Roentgen Ray Society
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crotal and penile trauma is an uncommon type of trauma injury, but prompt diagnosis is essential in the triage of patients with these injuries. Mechanisms of scrotal trauma include blunt, penetrating, and degloving injuries. More than one half of testicular injuries are caused by blunt trauma. Blunt trauma from being struck in the groin during athletic activity is the most common type. Blunt trauma due to motor vehicle collisions and assault accounts for only 9–17% of cases of blunt trauma [1]. Other mechanisms of trauma, such as penetrating, thermal (i.e., burns), and degloving injuries, are less common. Penetrating trauma is caused by gunshots (most common), stabbing, animal attack, and even self-mutilation. Thermal and degloving injuries are a less common form of scrotal injuries. With a degloving injury, the scrotal skin is sheared off, and a skin graft is necessary for repair [2]. Most penile injuries are related to sexual activity that results in penile fracture [3]. With these injuries, delay in diagnosis and inaccurate diagnosis can result in infection, ischemia, infarction, penile atrophy, and decreased fertility [4–7]. High-frequency ultrasound with a linear transducer and gray-scale, color, and spectral Doppler flow technique is the primary noninvasive modality for establishing an accurate diagnosis. It is used to assess the anatomic and physiologic integrity of the area and ob-
tain high-resolution images. The advantage of ultrasound is that it is readily available, inexpensive, portable, and can be performed without patient preparation [8–10]. This article reviews scrotal and penile anatomy, the role of ultrasound in evaluating scrotal and penile trauma, and the vast spectrum of sonographic manifestations of scrotal and penile trauma. Scrotal Anatomy The scrotum is divided by the midline septum, which is also referred to as the median raphe. Each half of the scrotum contains a spermatic cord, testis, and epididymis. The scrotal wall consists of the following layers from superficial to deep: rugated skin, superficial fascia, dartos muscle, external spermatic fascia, cremasteric fascia, and internal spermatic fascia. The testes are separated from the scrotum by the tunica vaginalis, which has two layers. The layer lining the scrotal wall is the parietal layer, and the layer extending over the testis and epididymis is the visceral layer. The tunica vaginalis covers the testis and epididymis except for a small area in the posterior aspect. A potential space between the visceral and parietal layers can normally contain a few milliliters of fluid. These two layers of the tunica vaginalis join at the posterolateral aspect of the testis, where it attaches to the scrotal wall. The tunica albuginea is a dense fibrous layer that lies deep to the tunica vaginalis.
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Scrotal and Penile Trauma Each testis is bound externally by the tunica albuginea, which helps to maintain its shape and integrity. The tunica albuginea appears as two bright echogenic lines at high-frequency sonography (Fig. 1). A testis measures 5 × 3 × 2 cm after puberty and is homogeneously echogenic at ultrasound. The testicular parenchyma consists of multiple lobules, each of which is composed of several seminiferous tubules that lead via tubuli recti to the dilated spaces known as the rete testis within the mediastinum. The epididymis, which overlies the superior and lateral aspects of the testis, is composed of a head, body, and tail. The head is a 5- to 12-mm triangular structure situated atop the superior pole of the testis. At ultrasound the head is isoechoic in relation to the testis. The body of the epididymis is 2–4 mm thick as it courses alongside the testicle inferiorly to become the tail, which continues as the vas deferens in the spermatic cord. Sonographic Evaluation of the Scrotum Standard ultrasound technique is performed with the patient lying supine with the scrotum supported by a towel between the thighs. For optimal results, a 7–14-MHz high-frequency linear-array transducer is used, and the gel should be warm. If the patient has an open wound, sterile technique is recommended. Immediately after trauma injury, the scrotum is often tender to palpation, which makes scanning exceptionally challenging. A complete evaluation of the anatomy of the scrotum should be performed even in the acute phase, when time is limited. Trans-
verse images with portions of each testis in the same image should be acquired in grayscale and color Doppler modes to allow optimal comparison (Fig. 1). Each testis is examined in at least two planes: longitudinal and transverse. In patients being evaluated for scrotal trauma, the asymptomatic side should be scanned first to set the gray-scale and color Doppler gain settings to allow comparison with the affected side [2]. Color Doppler and spectral Doppler parameters are optimized to low velocity settings to display blood flow within the testes and the surrounding structures. Pulsed Doppler recordings should be obtained in each testis (Fig. 2). The power Doppler mode is used to evaluate patients with acute scrotal pain when minimal flow is detected with standard settings. In addition to static images, cine clips of the scrotum can be obtained for careful scrutiny of the area after the examination. The structures within the sac and the scrotal skin thickness are also examined to evaluate for extratesticular injuries or other abnormalities, such as collections and hematomas. The sonographic characteristics of scrotal trauma can be broadly classified into intratesticular and extratesticular (epididymis) and intrascrotal and extrascrotal injuries (e.g., to the penis and perineum). Intratesticular Injuries Testicular Rupture The normal tunica albuginea appears as a hyperechoic line outlining the testis. The discontinuity of the tunica albuginea suggests rupture of the testis, which causes ex-
trusion of the testicular parenchyma, thus appearing as a contour abnormality within the scrotum (Fig. 3). The presence of tunica albuginea disruption alone has sensitivity and specificity of 50% and 75% for testicular injury [11]. Because of the rupture of the tunica albuginea, there is injury to the testicular parenchyma, which is seen as heterogeneous echogenicity within the testis. In addition, the disruption of the tunica vasculosa, which underlies the tunica albuginea and is composed of capsular arteries within the testis, is an indirect sign of tunica albuginea rupture [12]. This results in loss of vascularity to a portion of the testis. Therefore, the presence of heterogeneous echotexture within the testis, testicular contour abnormality due to disruption of the tunica albuginea, and regions of avascularity have the highest sensitivity and specificity for testicular rupture [5, 13]. Hedayati et al. [14] described the use of contrast material to assess for vascular flow to further delineate vascular compromise and evaluate the extent of viability of a ruptured testis. We do not use this technique at our institution. More than 80% of ruptured testes can be salvaged if surgical repair is performed within 72 hours of testicular injury [15]. Typically, testicular rupture is unilateral, but 1.5% of cases are bilateral [16]. On rare occasions, testicular rupture can be associated with epididymal ruptures, which may at times be difficult to detect with ultrasound. Testicular Fracture Testicular fracture is identified at ultrasound by the presence of a relatively linear
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Fig. 1—34-year-old man with right testicular pain. A, Sagittal gray-scale ultrasound image of normal right testis shows homogeneous echotexture. Tunica albuginea (arrows) appears as echogenic line surrounding testicle. B, Transverse bilateral color Doppler image shows normal symmetric blood flow.
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Nicola et al.
Fig. 2—25-year-old man with right testicular pain. Sagittal color and spectral Doppler image shows normal lowresistance arterial waveform.
hypoechoic, avascular area within the testicular parenchyma that may or may not be associated with tunica albuginea rupture [17]. Actual fracture lines through the testicle are rare in cases of testicular fracture [18]. Color Doppler ultrasound plays an important role in the evaluation of testicular fracture. Flow within the testicular parenchyma is indicative of salvageability. Frequently, débridement is performed along the fracture line,
and the rest of the vascular parenchyma is preserved [2, 12]. Hematoma Intratesticular hematomas are fairly common findings in blunt testicular trauma. The ultrasound appearance of a hematoma depends on the time that has elapsed between the trauma and the ultrasound evaluation. Hyperacute and acute hematomas are some-
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times difficult to identify because they can appear isoechoic in relation to the surrounding testis or may have a diffusely heterogeneous echotexture. For this reason, an acute hematoma is reexamined within 12–24 hours after the initial ultrasound examination to find any changes in echogenicity [12, 19]. As a hematoma evolves, it becomes more hypoechoic to anechoic and eventually decreases in size. Color Doppler can be used to differentiate such hematomas from the tumors included in the differential diagnosis of intratesticular lesions. A well-defined hematoma within the testis does not exhibit internal vascularity except when it is infected [12] (Fig. 4). In patients with hematoma, the most important role of ultrasound is to exclude testicular rupture, because the care of these patients can depend primarily on the ultrasound findings. Small hematomas without direct evidence of testicular rupture are managed conservatively with ice packs, nonsteroidal antiinflammatory drugs, follow-up physical examinations, and serial ultrasound examinations [5]. Follow-up ultrasound of all conservatively treated intratesticular hematomas until they resolve is essential because of the high incidence of infection and necrosis, which may require orchiectomy [12]. Another reason for follow-up ultrasound is that a testicular tumor should be considered in the differential diagnosis of intratesticular lesions. Lesions are excluded if the area of concern shows interval resolution [19]. It is recommended that large intratesticular hematomas be surgically explored and
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Fig. 3—32-year-old man with scrotal rupture due to motor vehicle accident. A, Longitudinal gray-scale ultrasound image of right testis shows disruption of tunica albuginea (straight arrow) that results in contour abnormality (asterisk) and formation of focal hematoma (curved arrow). B, Color Doppler image shows decreased vascularity within ruptured segment of testis (arrowhead) and no vascularity in focal hematoma (arrow). Patient underwent surgical débridement.
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Fig. 4—30-year-old man with testicular hematoma resulting from sports injury. A, Longitudinal gray-scale ultrasound image of left testis shows intratesticular hypoechoic region (arrow) suggestive of intratesticular hematoma. B, Color Doppler image shows no vascularity within hematoma (arrow).
Fig. 5—45-year-old man with hematocele and hematoma due to scrotal trauma. Transverse grayscale ultrasound image of left testis shows hematocele and hematoma (asterisks) with hematocrit levels. T = testis.
drained even if there is no evidence of testicular rupture or large extratesticular hematocele. The purpose is to avoid progressive pressure necrosis, atrophy, and orchiectomy [20]. Extratesticular Injuries Scrotal Hematoma or Hematocele Extratesticular hematoceles, or collections of blood within the tunica vaginalis, are the most common finding in the scrotum after blunt trauma [12]. Micallef et al. [13] noted such findings in 11 of 15 patients. Extratesticular soft tissues, such as the scrotal wall, tunica albuginea, and epididymis, may also be involved. The ultrasound appearance of an extratesticular hematocele or hematoma varies with the age of the lesion.
Acute hematocele is echogenic in appearance, whereas chronic hematocele is more anechoic, can develop septa and loculations, and may not resolve [21] (Fig. 5). It may also become calcified and mimic an extratesticular calcified mass. In the acute phase, a large hematocele can cause extrinsic compression on surrounding blood vessels and reduce blood flow, resembling complete or partial torsion. Therefore, emergency surgical evacuation of the extratesticular hematoma is necessary to restore blood flow and salvage the testis. A large hematocele also requires surgical exploration irrespective of evidence of tunica albuginea rupture. The reason for this step is that ultrasound has limited utility in identifying tu-
Fig. 6—47-year-old man with scrotal wall hematoma after sports injury. Gray-scale ultrasound image shows heterogeneous scrotal wall thickening (arrows) secondary to hemorrhage and small hematocele (arrowhead). Testis (T) is not injured.
nica rupture in the presence of a large hematoma [22]. Posttraumatic hematomas can be confined to the scrotal wall, where they appear at ultrasound as focal thickening or a fluid collection within the wall (Fig. 6). Traumatic Epididymitis Traumatic epididymitis is uncommon, but it can occur in patients who have sustained acute scrotal trauma. The ultrasound findings of traumatic epididymitis are an enlarged heterogeneous epididymal head that is
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Nicola et al. hypoechoic in relation to the testis owing to swelling and edema. Color Doppler imaging also shows increased flow in the epididymal head [23] (Fig. 7). Heterogeneity of the epididymal head can be secondary to hematoma or contusion [15, 24]. Although this appearance is similar to that of infectious epididymitis, the history of recent traumatic injury suggests traumatic epididymitis. However, infectious epididymitis is more common [19]. Testicular Torsion Trauma-induced testicular torsion is a well-known phenomenon and a surgical emergency. Traumatic torsion can be caused by stimulating forceful contraction of the cremaster muscles. Both gray-scale and color-flow Doppler evaluations are essential for evaluating the alterations caused by trauma. The sonographic characteristics of posttraumatic testicular torsion are similar to those of spontaneous testicular torsion [1]. Testicular Dislocation Testicular dislocation is uncommon after trauma injury, and it is difficult to diagnose with ultrasound examination after acute trauma. Unless the sonographer or the radiologist is aware of it, testicular dislocation can be easily missed. Testicular dislocation is typically unilateral and rarely bilateral [25]. It usually occurs in straddle injuries in motorcycle accidents when the rider is propelled forward, and the scrotum and perineum strike the fuel tank. The fuel tank acts as a smooth wedge driving into the groin area, forcibly displacing each testis in the superolateral direction [26, 27]. Patients with a wide external inguinal ring, an indirect inguinal hernia, or an atrophic testis are more vulnerable to testicular dis-
location due to trauma [28, 29]. The dislocated testis can be anywhere along the spermatic cord. The superficial inguinal area is the most common site of dislocation. Other sites such as perineal, retrovesical, and even acetabular regions are much less common [30, 31]. The diagnosis of testicular dislocation can be made when palpation reveals an empty and ecchymotic hemiscrotum and an ipsilateral inguinal mass. Color-flow Doppler ultrasound is essential for evaluating the viability of the testis. If the dislocated testis is viable, manual reduction is performed. If this maneuver is not successful, immediate surgical reduction and fixation are necessary [32]. Penile Anatomy The penis consists of a pair of corpora cavernosa along its dorsal aspect and a midline corpus spongiosum along its ventral surface. The crura of the corpora cavernosa are attached to the ischial tuberosities. The corpora cavernosa are composed of venous sinusoids that fill with blood during erection, and they are surrounded by the tunica albuginea. The corpus spongiosum surrounds the urethra and expands anteriorly to form the glans penis; it is also surrounded by the glans tunica albuginea. The three corpora combined are surrounded by two fascial layers: the superficial Colles fascia and the deeper Buck fascia. The tunica albuginea is the deepest fibrous layer and surrounds each corpus individually. On transverse images, the two corpora cavernosa are seen as symmetric homogeneous midlevel-echo circular structures that are surrounded by an echogenic line representing the tunica albuginea (Fig. 8). The two corpora cavernosa are separated by the septum penis, an extension of the tunica al-
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buginea, which appears as a thin echogenic line. When the penis becomes erect, the two corpora cavernosa enlarge and the sinusoids dilate, changing the echogenicity from homogeneous to hypoechoic. The arterial supply to the penis is from the dorsal artery, which is lateral to the deep dorsal vein and supplies the glans penis and skin. The cavernosal artery is a terminal branch of the internal pudendal artery. It is located within the center of the corpus cavernosum and provides arterial flow during erection. The urethral bulb and posterior corpus spongiosum are supplied by the bulbourethral artery, which is known as the urethral bulb. The venous supply is through the dorsal veins: the superficial dorsal vein, which is superficial to the Buck fascia, and the deep dorsal vein, which is deep to the Buck fascia. Sonographic Evaluation of the Penis The standard technique for ultrasound of the penis is performed with the patient in the supine or lithotomy (frog-leg) position and the penis in the anatomic position, lying on the anterior abdominal wall. Longitudinal and transverse gray-scale and Doppler colorflow images of the entire length of the penis should be obtained with a high-frequency (7.5–12-MHz) linear array transducer and acoustic gel. A transperineal approach with elevation of the testes is used to assess the base of the penis. The cavernosal artery is located within the center of the corpus cavernosum or slightly toward the median septum penis and is noted in both longitudinal and transverse views. It appears as two echogenic dots on transverse images and as a tubular structure with echogenic walls on longitudinal images (Fig. 8). The
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Fig. 7—26-year-old man with traumatic epididymitis due to sports injury. A, Longitudinal gray-scale image of epididymis shows enlarged heterogeneous epididymis (arrow). Heterogeneity is due to multiple, small, avascular hematomas. Calipers = testis. B, Color Doppler image shows increased vascularity within epididymis (arrow), whereas contusions have no vascularity.
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venous drainage of the corpora cavernosa is through the small emissary veins, which drain into the dorsal, cavernosal, and crural veins. Penile Trauma Penile Fracture A penile fracture typically occurs in the proximal or mid shaft of the erect penis. Concomitant injury to the penile urethra occurs in approximately 10–20% of cases and should be suspected if blood is found within the urethral meatus or if cavernosal injury is bilateral [33, 34]. Patients with penile fracture report hearing a cracking or popping sound and feeling sharp pain followed by rapid detumescence, swelling, discoloration, and deformity of the penis, which is commonly described as eggplant deformity [3]. Penile fractures are urologic emergencies and require immediate surgical exploration. However, the diagnosis is usually delayed because of the patient’s embarrassment. The benefits of ultrasound are that it can be used to evaluate normal anatomy and the extent of injury and that it depicts the exact
location of the tear within the tunica albuginea [35–38] (Fig. 9). In addition to ultrasound, MRI can show excellent soft-tissue delineation in evaluation of the integrity of the tunica albuginea, which is hypointense on images obtained with all pulse sequences whether or not a hematoma is present [39]. Priapism Priapism is defined as a prolonged penile erection not associated with sexual desire. Priapism is categorized as either low flow (ischemic) or high flow (nonischemic). Malfunction of normal penile flow due to hypercoagulability, sickle cell disease, or medication results in prolonged obstruction of venous outflow leading to high cavernous pressure, which causes irreversible ischemic changes and permanent erectile dysfunction. Therefore, priapism is considered a true emergency [39]. High-flow priapism is caused by unregulated arterial flow due to arterial trauma. Patients typically present with a painless erection after genitourinary trauma. This is not
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considered an emergency because it is not associated with pain, and permanent erectile dysfunction is unlikely. Although the cause of priapism may be known clinically, a cavernosa blood gas level may be necessary to confirm the diagnosis with high oxygen tension. A less invasive method is Doppler ultrasound to evaluate the vascularity of the penis. Color and spectral Doppler ultrasound depicts high blood flow within the cavernosal artery (Fig. 10). Intracavernosal Hematoma Injury to the subtunical venous plexus or smooth-muscle trabecula in the absence of complete tunical disruption can lead to a cavernosal hematoma [40]. Intracavernosal hematomas are usually bilateral and result from injury to the cavernosal tissue when the base of the penis is crushed against the pelvic bones [38]. The sonographic appearance of a penile hematoma can vary with its age. In the acute phase, a hematoma is usually hyperechoic and eventually becomes a cystic lesion with septation [3]. Cavernosal damage
Fig. 8—53-year-old man with normal penis. A, Drawing shows normal penile anatomy. B and C, Transverse gray-scale (B) and longitudinal color Doppler (C) ultrasound images of normal penis show corpora cavernosa (straight arrows, B), corpus spongiosum (large arrowhead, B), cavernosal arteries (small arrowheads), and tunica albuginea (curved arrow, B).
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Fig. 9—40-year-old man with fractured penis. A, Transverse gray-scale image of penis shows disruption of tunica (straight arrow) on left, right corpus cavernosum (arrowhead), and corpus spongiosum (curved arrow). B, Longitudinal color Doppler image shows disruption of tunica (arrow) on left that results in organized hematoma (asterisk) under Buck fascia. C, Intraoperative photograph shows disruption of tunica albuginea (arrow).
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Fig. 10—56-year-old man in emergency department with partial tumescence due to high-flow priapism. A and B, Transverse (A) and longitudinal (B) color and spectral Doppler images of penis show arteriovenous fistula (arrow) between cavernosal artery and vein secondary to trauma during sexual activity.
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Fig. 11—40-year-old man with pain and swelling due to cavernosal hematoma resulting from penile trauma sustained during intercourse. Transverse gray-scale ultrasound image shows echogenic hematoma (arrow) within left corpus.
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Fig. 12—34-year-old man with dorsal vein thrombosis after sexual activity. A and B, Transverse (A) and longitudinal (B) gray-scale ultrasound images show thrombosed dorsal vein (arrow).
can cause fibrosis, which at ultrasound appears as an ill-defined echogenic scar replacing the erectile tissue [41] (Fig. 11). If the tunica albuginea is intact, the patient can be treated conservatively.
the clinical and sonographic appearance can mimic those of penile fracture. Ultrasound shows a noncompressible dorsal vein; if rupture has occurred, signs of hematoma also are present [43] (Fig. 12).
Traumatic Avulsion of the Dorsal Penile Vessels and Thrombosis Rupture of the dorsal penile vessels can be caused by sexual activity and mimics a penile fracture [42]. However, deformity and immediate detumescence of the penis do not occur because the tunica albuginea is intact [38]. This typically can be associated with a hematoma. The hematoma can be either superficial or remain under the Buck fascia, depending on the site of involvement of the penile veins. If an arterial lesion is present, a posttraumatic arteriovenous fistula with increased venous pressures and dilation of the injured vessels may result [38]. Thrombosis of the superficial and deep dorsal penile veins is a urologic emergency. However,
Summary Scrotal and penile trauma is an uncommon type of trauma injury. It is important for radiologists to become familiar with specific ultrasound findings to make a prompt diagnosis so that the patient can be treated appropriately. Ultrasound is typically the modality of choice because of its accessibility, mobility, and noninvasiveness and because patient preparation is not necessary. In addition, the use of color-flow, power, and spectral Doppler techniques and high-resolution imaging facilitates accurate assessment of the integrity of the scrotum and penis, which is important in directing patient care by either surgical exploration or conservative treatment.
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Genitourinary Imaging Review
Refky Nicola1 Nancy Carson Vikram S. Dogra Nicola R, Carson N, Dogra VS
Imaging of Traumatic Injuries to the Scrotum and Penis OBJECTIVE. The purpose of this article is to review scrotal and penile anatomy, the role of ultrasound in evaluating scrotal and penile trauma, and the vast spectrum of sonographic manifestations of scrotal and penile trauma. CONCLUSION. Scrotal and penile trauma is an uncommon type of trauma injury. However, knowledge of scrotal and penile anatomy and the appropriate imaging findings associated with acute traumatic injuries is important in establishing the correct diagnosis. Sonography is considered the first choice of imaging modalities in establishing a diagnosis and triaging patients into surgical and nonsurgical treatment.
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Keywords: Doppler, penis, scrotum, testis, trauma, ultrasound DOI:10.2214/AJR.13.11676 Received August 5, 2013; accepted after revision September 20, 2013. Presented at the 2013 annual meeting of the ARRS, Washington DC. 1
All authors: Department of Radiology, University of Rochester Medical Center, 601 Elmwood Ave, PO Box 648, Rochester, NY 14642. Address correspondence to V. S. Dogra ([email protected]).
This article is available for credit. WEB This is a web exclusive article. AJR 2014; 202:W512–W520 0361–803X/14/2026–W512 © American Roentgen Ray Society
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crotal and penile trauma is an uncommon type of trauma injury, but prompt diagnosis is essential in the triage of patients with these injuries. Mechanisms of scrotal trauma include blunt, penetrating, and degloving injuries. More than one half of testicular injuries are caused by blunt trauma. Blunt trauma from being struck in the groin during athletic activity is the most common type. Blunt trauma due to motor vehicle collisions and assault accounts for only 9–17% of cases of blunt trauma [1]. Other mechanisms of trauma, such as penetrating, thermal (i.e., burns), and degloving injuries, are less common. Penetrating trauma is caused by gunshots (most common), stabbing, animal attack, and even self-mutilation. Thermal and degloving injuries are a less common form of scrotal injuries. With a degloving injury, the scrotal skin is sheared off, and a skin graft is necessary for repair [2]. Most penile injuries are related to sexual activity that results in penile fracture [3]. With these injuries, delay in diagnosis and inaccurate diagnosis can result in infection, ischemia, infarction, penile atrophy, and decreased fertility [4–7]. High-frequency ultrasound with a linear transducer and gray-scale, color, and spectral Doppler flow technique is the primary noninvasive modality for establishing an accurate diagnosis. It is used to assess the anatomic and physiologic integrity of the area and ob-
tain high-resolution images. The advantage of ultrasound is that it is readily available, inexpensive, portable, and can be performed without patient preparation [8–10]. This article reviews scrotal and penile anatomy, the role of ultrasound in evaluating scrotal and penile trauma, and the vast spectrum of sonographic manifestations of scrotal and penile trauma. Scrotal Anatomy The scrotum is divided by the midline septum, which is also referred to as the median raphe. Each half of the scrotum contains a spermatic cord, testis, and epididymis. The scrotal wall consists of the following layers from superficial to deep: rugated skin, superficial fascia, dartos muscle, external spermatic fascia, cremasteric fascia, and internal spermatic fascia. The testes are separated from the scrotum by the tunica vaginalis, which has two layers. The layer lining the scrotal wall is the parietal layer, and the layer extending over the testis and epididymis is the visceral layer. The tunica vaginalis covers the testis and epididymis except for a small area in the posterior aspect. A potential space between the visceral and parietal layers can normally contain a few milliliters of fluid. These two layers of the tunica vaginalis join at the posterolateral aspect of the testis, where it attaches to the scrotal wall. The tunica albuginea is a dense fibrous layer that lies deep to the tunica vaginalis.
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Scrotal and Penile Trauma Each testis is bound externally by the tunica albuginea, which helps to maintain its shape and integrity. The tunica albuginea appears as two bright echogenic lines at high-frequency sonography (Fig. 1). A testis measures 5 × 3 × 2 cm after puberty and is homogeneously echogenic at ultrasound. The testicular parenchyma consists of multiple lobules, each of which is composed of several seminiferous tubules that lead via tubuli recti to the dilated spaces known as the rete testis within the mediastinum. The epididymis, which overlies the superior and lateral aspects of the testis, is composed of a head, body, and tail. The head is a 5- to 12-mm triangular structure situated atop the superior pole of the testis. At ultrasound the head is isoechoic in relation to the testis. The body of the epididymis is 2–4 mm thick as it courses alongside the testicle inferiorly to become the tail, which continues as the vas deferens in the spermatic cord. Sonographic Evaluation of the Scrotum Standard ultrasound technique is performed with the patient lying supine with the scrotum supported by a towel between the thighs. For optimal results, a 7–14-MHz high-frequency linear-array transducer is used, and the gel should be warm. If the patient has an open wound, sterile technique is recommended. Immediately after trauma injury, the scrotum is often tender to palpation, which makes scanning exceptionally challenging. A complete evaluation of the anatomy of the scrotum should be performed even in the acute phase, when time is limited. Trans-
verse images with portions of each testis in the same image should be acquired in grayscale and color Doppler modes to allow optimal comparison (Fig. 1). Each testis is examined in at least two planes: longitudinal and transverse. In patients being evaluated for scrotal trauma, the asymptomatic side should be scanned first to set the gray-scale and color Doppler gain settings to allow comparison with the affected side [2]. Color Doppler and spectral Doppler parameters are optimized to low velocity settings to display blood flow within the testes and the surrounding structures. Pulsed Doppler recordings should be obtained in each testis (Fig. 2). The power Doppler mode is used to evaluate patients with acute scrotal pain when minimal flow is detected with standard settings. In addition to static images, cine clips of the scrotum can be obtained for careful scrutiny of the area after the examination. The structures within the sac and the scrotal skin thickness are also examined to evaluate for extratesticular injuries or other abnormalities, such as collections and hematomas. The sonographic characteristics of scrotal trauma can be broadly classified into intratesticular and extratesticular (epididymis) and intrascrotal and extrascrotal injuries (e.g., to the penis and perineum). Intratesticular Injuries Testicular Rupture The normal tunica albuginea appears as a hyperechoic line outlining the testis. The discontinuity of the tunica albuginea suggests rupture of the testis, which causes ex-
trusion of the testicular parenchyma, thus appearing as a contour abnormality within the scrotum (Fig. 3). The presence of tunica albuginea disruption alone has sensitivity and specificity of 50% and 75% for testicular injury [11]. Because of the rupture of the tunica albuginea, there is injury to the testicular parenchyma, which is seen as heterogeneous echogenicity within the testis. In addition, the disruption of the tunica vasculosa, which underlies the tunica albuginea and is composed of capsular arteries within the testis, is an indirect sign of tunica albuginea rupture [12]. This results in loss of vascularity to a portion of the testis. Therefore, the presence of heterogeneous echotexture within the testis, testicular contour abnormality due to disruption of the tunica albuginea, and regions of avascularity have the highest sensitivity and specificity for testicular rupture [5, 13]. Hedayati et al. [14] described the use of contrast material to assess for vascular flow to further delineate vascular compromise and evaluate the extent of viability of a ruptured testis. We do not use this technique at our institution. More than 80% of ruptured testes can be salvaged if surgical repair is performed within 72 hours of testicular injury [15]. Typically, testicular rupture is unilateral, but 1.5% of cases are bilateral [16]. On rare occasions, testicular rupture can be associated with epididymal ruptures, which may at times be difficult to detect with ultrasound. Testicular Fracture Testicular fracture is identified at ultrasound by the presence of a relatively linear
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Fig. 1—34-year-old man with right testicular pain. A, Sagittal gray-scale ultrasound image of normal right testis shows homogeneous echotexture. Tunica albuginea (arrows) appears as echogenic line surrounding testicle. B, Transverse bilateral color Doppler image shows normal symmetric blood flow.
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Nicola et al.
Fig. 2—25-year-old man with right testicular pain. Sagittal color and spectral Doppler image shows normal lowresistance arterial waveform.
hypoechoic, avascular area within the testicular parenchyma that may or may not be associated with tunica albuginea rupture [17]. Actual fracture lines through the testicle are rare in cases of testicular fracture [18]. Color Doppler ultrasound plays an important role in the evaluation of testicular fracture. Flow within the testicular parenchyma is indicative of salvageability. Frequently, débridement is performed along the fracture line,
and the rest of the vascular parenchyma is preserved [2, 12]. Hematoma Intratesticular hematomas are fairly common findings in blunt testicular trauma. The ultrasound appearance of a hematoma depends on the time that has elapsed between the trauma and the ultrasound evaluation. Hyperacute and acute hematomas are some-
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times difficult to identify because they can appear isoechoic in relation to the surrounding testis or may have a diffusely heterogeneous echotexture. For this reason, an acute hematoma is reexamined within 12–24 hours after the initial ultrasound examination to find any changes in echogenicity [12, 19]. As a hematoma evolves, it becomes more hypoechoic to anechoic and eventually decreases in size. Color Doppler can be used to differentiate such hematomas from the tumors included in the differential diagnosis of intratesticular lesions. A well-defined hematoma within the testis does not exhibit internal vascularity except when it is infected [12] (Fig. 4). In patients with hematoma, the most important role of ultrasound is to exclude testicular rupture, because the care of these patients can depend primarily on the ultrasound findings. Small hematomas without direct evidence of testicular rupture are managed conservatively with ice packs, nonsteroidal antiinflammatory drugs, follow-up physical examinations, and serial ultrasound examinations [5]. Follow-up ultrasound of all conservatively treated intratesticular hematomas until they resolve is essential because of the high incidence of infection and necrosis, which may require orchiectomy [12]. Another reason for follow-up ultrasound is that a testicular tumor should be considered in the differential diagnosis of intratesticular lesions. Lesions are excluded if the area of concern shows interval resolution [19]. It is recommended that large intratesticular hematomas be surgically explored and
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Fig. 3—32-year-old man with scrotal rupture due to motor vehicle accident. A, Longitudinal gray-scale ultrasound image of right testis shows disruption of tunica albuginea (straight arrow) that results in contour abnormality (asterisk) and formation of focal hematoma (curved arrow). B, Color Doppler image shows decreased vascularity within ruptured segment of testis (arrowhead) and no vascularity in focal hematoma (arrow). Patient underwent surgical débridement.
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Fig. 4—30-year-old man with testicular hematoma resulting from sports injury. A, Longitudinal gray-scale ultrasound image of left testis shows intratesticular hypoechoic region (arrow) suggestive of intratesticular hematoma. B, Color Doppler image shows no vascularity within hematoma (arrow).
Fig. 5—45-year-old man with hematocele and hematoma due to scrotal trauma. Transverse grayscale ultrasound image of left testis shows hematocele and hematoma (asterisks) with hematocrit levels. T = testis.
drained even if there is no evidence of testicular rupture or large extratesticular hematocele. The purpose is to avoid progressive pressure necrosis, atrophy, and orchiectomy [20]. Extratesticular Injuries Scrotal Hematoma or Hematocele Extratesticular hematoceles, or collections of blood within the tunica vaginalis, are the most common finding in the scrotum after blunt trauma [12]. Micallef et al. [13] noted such findings in 11 of 15 patients. Extratesticular soft tissues, such as the scrotal wall, tunica albuginea, and epididymis, may also be involved. The ultrasound appearance of an extratesticular hematocele or hematoma varies with the age of the lesion.
Acute hematocele is echogenic in appearance, whereas chronic hematocele is more anechoic, can develop septa and loculations, and may not resolve [21] (Fig. 5). It may also become calcified and mimic an extratesticular calcified mass. In the acute phase, a large hematocele can cause extrinsic compression on surrounding blood vessels and reduce blood flow, resembling complete or partial torsion. Therefore, emergency surgical evacuation of the extratesticular hematoma is necessary to restore blood flow and salvage the testis. A large hematocele also requires surgical exploration irrespective of evidence of tunica albuginea rupture. The reason for this step is that ultrasound has limited utility in identifying tu-
Fig. 6—47-year-old man with scrotal wall hematoma after sports injury. Gray-scale ultrasound image shows heterogeneous scrotal wall thickening (arrows) secondary to hemorrhage and small hematocele (arrowhead). Testis (T) is not injured.
nica rupture in the presence of a large hematoma [22]. Posttraumatic hematomas can be confined to the scrotal wall, where they appear at ultrasound as focal thickening or a fluid collection within the wall (Fig. 6). Traumatic Epididymitis Traumatic epididymitis is uncommon, but it can occur in patients who have sustained acute scrotal trauma. The ultrasound findings of traumatic epididymitis are an enlarged heterogeneous epididymal head that is
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Nicola et al. hypoechoic in relation to the testis owing to swelling and edema. Color Doppler imaging also shows increased flow in the epididymal head [23] (Fig. 7). Heterogeneity of the epididymal head can be secondary to hematoma or contusion [15, 24]. Although this appearance is similar to that of infectious epididymitis, the history of recent traumatic injury suggests traumatic epididymitis. However, infectious epididymitis is more common [19]. Testicular Torsion Trauma-induced testicular torsion is a well-known phenomenon and a surgical emergency. Traumatic torsion can be caused by stimulating forceful contraction of the cremaster muscles. Both gray-scale and color-flow Doppler evaluations are essential for evaluating the alterations caused by trauma. The sonographic characteristics of posttraumatic testicular torsion are similar to those of spontaneous testicular torsion [1]. Testicular Dislocation Testicular dislocation is uncommon after trauma injury, and it is difficult to diagnose with ultrasound examination after acute trauma. Unless the sonographer or the radiologist is aware of it, testicular dislocation can be easily missed. Testicular dislocation is typically unilateral and rarely bilateral [25]. It usually occurs in straddle injuries in motorcycle accidents when the rider is propelled forward, and the scrotum and perineum strike the fuel tank. The fuel tank acts as a smooth wedge driving into the groin area, forcibly displacing each testis in the superolateral direction [26, 27]. Patients with a wide external inguinal ring, an indirect inguinal hernia, or an atrophic testis are more vulnerable to testicular dis-
location due to trauma [28, 29]. The dislocated testis can be anywhere along the spermatic cord. The superficial inguinal area is the most common site of dislocation. Other sites such as perineal, retrovesical, and even acetabular regions are much less common [30, 31]. The diagnosis of testicular dislocation can be made when palpation reveals an empty and ecchymotic hemiscrotum and an ipsilateral inguinal mass. Color-flow Doppler ultrasound is essential for evaluating the viability of the testis. If the dislocated testis is viable, manual reduction is performed. If this maneuver is not successful, immediate surgical reduction and fixation are necessary [32]. Penile Anatomy The penis consists of a pair of corpora cavernosa along its dorsal aspect and a midline corpus spongiosum along its ventral surface. The crura of the corpora cavernosa are attached to the ischial tuberosities. The corpora cavernosa are composed of venous sinusoids that fill with blood during erection, and they are surrounded by the tunica albuginea. The corpus spongiosum surrounds the urethra and expands anteriorly to form the glans penis; it is also surrounded by the glans tunica albuginea. The three corpora combined are surrounded by two fascial layers: the superficial Colles fascia and the deeper Buck fascia. The tunica albuginea is the deepest fibrous layer and surrounds each corpus individually. On transverse images, the two corpora cavernosa are seen as symmetric homogeneous midlevel-echo circular structures that are surrounded by an echogenic line representing the tunica albuginea (Fig. 8). The two corpora cavernosa are separated by the septum penis, an extension of the tunica al-
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buginea, which appears as a thin echogenic line. When the penis becomes erect, the two corpora cavernosa enlarge and the sinusoids dilate, changing the echogenicity from homogeneous to hypoechoic. The arterial supply to the penis is from the dorsal artery, which is lateral to the deep dorsal vein and supplies the glans penis and skin. The cavernosal artery is a terminal branch of the internal pudendal artery. It is located within the center of the corpus cavernosum and provides arterial flow during erection. The urethral bulb and posterior corpus spongiosum are supplied by the bulbourethral artery, which is known as the urethral bulb. The venous supply is through the dorsal veins: the superficial dorsal vein, which is superficial to the Buck fascia, and the deep dorsal vein, which is deep to the Buck fascia. Sonographic Evaluation of the Penis The standard technique for ultrasound of the penis is performed with the patient in the supine or lithotomy (frog-leg) position and the penis in the anatomic position, lying on the anterior abdominal wall. Longitudinal and transverse gray-scale and Doppler colorflow images of the entire length of the penis should be obtained with a high-frequency (7.5–12-MHz) linear array transducer and acoustic gel. A transperineal approach with elevation of the testes is used to assess the base of the penis. The cavernosal artery is located within the center of the corpus cavernosum or slightly toward the median septum penis and is noted in both longitudinal and transverse views. It appears as two echogenic dots on transverse images and as a tubular structure with echogenic walls on longitudinal images (Fig. 8). The
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Fig. 7—26-year-old man with traumatic epididymitis due to sports injury. A, Longitudinal gray-scale image of epididymis shows enlarged heterogeneous epididymis (arrow). Heterogeneity is due to multiple, small, avascular hematomas. Calipers = testis. B, Color Doppler image shows increased vascularity within epididymis (arrow), whereas contusions have no vascularity.
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venous drainage of the corpora cavernosa is through the small emissary veins, which drain into the dorsal, cavernosal, and crural veins. Penile Trauma Penile Fracture A penile fracture typically occurs in the proximal or mid shaft of the erect penis. Concomitant injury to the penile urethra occurs in approximately 10–20% of cases and should be suspected if blood is found within the urethral meatus or if cavernosal injury is bilateral [33, 34]. Patients with penile fracture report hearing a cracking or popping sound and feeling sharp pain followed by rapid detumescence, swelling, discoloration, and deformity of the penis, which is commonly described as eggplant deformity [3]. Penile fractures are urologic emergencies and require immediate surgical exploration. However, the diagnosis is usually delayed because of the patient’s embarrassment. The benefits of ultrasound are that it can be used to evaluate normal anatomy and the extent of injury and that it depicts the exact
location of the tear within the tunica albuginea [35–38] (Fig. 9). In addition to ultrasound, MRI can show excellent soft-tissue delineation in evaluation of the integrity of the tunica albuginea, which is hypointense on images obtained with all pulse sequences whether or not a hematoma is present [39]. Priapism Priapism is defined as a prolonged penile erection not associated with sexual desire. Priapism is categorized as either low flow (ischemic) or high flow (nonischemic). Malfunction of normal penile flow due to hypercoagulability, sickle cell disease, or medication results in prolonged obstruction of venous outflow leading to high cavernous pressure, which causes irreversible ischemic changes and permanent erectile dysfunction. Therefore, priapism is considered a true emergency [39]. High-flow priapism is caused by unregulated arterial flow due to arterial trauma. Patients typically present with a painless erection after genitourinary trauma. This is not
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considered an emergency because it is not associated with pain, and permanent erectile dysfunction is unlikely. Although the cause of priapism may be known clinically, a cavernosa blood gas level may be necessary to confirm the diagnosis with high oxygen tension. A less invasive method is Doppler ultrasound to evaluate the vascularity of the penis. Color and spectral Doppler ultrasound depicts high blood flow within the cavernosal artery (Fig. 10). Intracavernosal Hematoma Injury to the subtunical venous plexus or smooth-muscle trabecula in the absence of complete tunical disruption can lead to a cavernosal hematoma [40]. Intracavernosal hematomas are usually bilateral and result from injury to the cavernosal tissue when the base of the penis is crushed against the pelvic bones [38]. The sonographic appearance of a penile hematoma can vary with its age. In the acute phase, a hematoma is usually hyperechoic and eventually becomes a cystic lesion with septation [3]. Cavernosal damage
Fig. 8—53-year-old man with normal penis. A, Drawing shows normal penile anatomy. B and C, Transverse gray-scale (B) and longitudinal color Doppler (C) ultrasound images of normal penis show corpora cavernosa (straight arrows, B), corpus spongiosum (large arrowhead, B), cavernosal arteries (small arrowheads), and tunica albuginea (curved arrow, B).
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Fig. 9—40-year-old man with fractured penis. A, Transverse gray-scale image of penis shows disruption of tunica (straight arrow) on left, right corpus cavernosum (arrowhead), and corpus spongiosum (curved arrow). B, Longitudinal color Doppler image shows disruption of tunica (arrow) on left that results in organized hematoma (asterisk) under Buck fascia. C, Intraoperative photograph shows disruption of tunica albuginea (arrow).
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Fig. 10—56-year-old man in emergency department with partial tumescence due to high-flow priapism. A and B, Transverse (A) and longitudinal (B) color and spectral Doppler images of penis show arteriovenous fistula (arrow) between cavernosal artery and vein secondary to trauma during sexual activity.
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Fig. 11—40-year-old man with pain and swelling due to cavernosal hematoma resulting from penile trauma sustained during intercourse. Transverse gray-scale ultrasound image shows echogenic hematoma (arrow) within left corpus.
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Fig. 12—34-year-old man with dorsal vein thrombosis after sexual activity. A and B, Transverse (A) and longitudinal (B) gray-scale ultrasound images show thrombosed dorsal vein (arrow).
can cause fibrosis, which at ultrasound appears as an ill-defined echogenic scar replacing the erectile tissue [41] (Fig. 11). If the tunica albuginea is intact, the patient can be treated conservatively.
the clinical and sonographic appearance can mimic those of penile fracture. Ultrasound shows a noncompressible dorsal vein; if rupture has occurred, signs of hematoma also are present [43] (Fig. 12).
Traumatic Avulsion of the Dorsal Penile Vessels and Thrombosis Rupture of the dorsal penile vessels can be caused by sexual activity and mimics a penile fracture [42]. However, deformity and immediate detumescence of the penis do not occur because the tunica albuginea is intact [38]. This typically can be associated with a hematoma. The hematoma can be either superficial or remain under the Buck fascia, depending on the site of involvement of the penile veins. If an arterial lesion is present, a posttraumatic arteriovenous fistula with increased venous pressures and dilation of the injured vessels may result [38]. Thrombosis of the superficial and deep dorsal penile veins is a urologic emergency. However,
Summary Scrotal and penile trauma is an uncommon type of trauma injury. It is important for radiologists to become familiar with specific ultrasound findings to make a prompt diagnosis so that the patient can be treated appropriately. Ultrasound is typically the modality of choice because of its accessibility, mobility, and noninvasiveness and because patient preparation is not necessary. In addition, the use of color-flow, power, and spectral Doppler techniques and high-resolution imaging facilitates accurate assessment of the integrity of the scrotum and penis, which is important in directing patient care by either surgical exploration or conservative treatment.
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