Chapter 13. Testicular

Acute testicular pain represents about 0.5% of ED complaints.1 Causes of acute testicular pain include trauma, epididymitis, orchitis, torsion of the testicular appendage, and hernia; however, testicular torsion is the diagnosis of the greatest concern in the emergency setting.

The traditional teaching was that most patients presenting to an ED or urgent care with a complaint of acute testicular pain had testicular torsion.2 This misconception has been dispelled and it is now known that the most common etiology of acute testicular pain is epididymitis.2 However, the evaluation of acute testicular pain presents a considerable challenge for emergency providers, since 50% of patients presenting with testicular torsion have delayed seeking care for >6 hours and are at high risk of losing the torsed testicle.3

The issue of acute testicular pain is further complicated by the high potential for litigation associated with infertility after testicular loss due to torsion or disruption of the testicle from severe trauma. When the diagnosis of testicular torsion is missed, the majority of patients have been incorrectly diagnosed with epididymitis.4

High-resolution color Doppler ultrasonography has become widely accepted as the test of choice for evaluating acute scrotal pain, replacing scintigraphy in most institutions.5 While scintigraphy requires less technical skill on the part of the radiologist consulted to evaluate the patient, there are major drawbacks to the technique. Scintigraphy is a time-consuming process that can add an hour or more to the evaluation of a patient who may already be several hours into the testicular torsion process.5 Furthermore, the resultant hyperemia of the scrotal skin during testicular torsion can mask a lack of blood flow to the testicle itself and lead to a misdiagnosis in less experienced hands.6 This nuclear medicine study also provides no information regarding testicular anatomy, which is a critical issue if pathology other than torsion is present. MRI is a promising imaging modality for detecting acute scrotal problems, including ischemia caused by torsion. However, MRI is expensive and time consuming.

Traditionally the history and physical examination were thought to be the keys to diagnosing or ruling out testicular torsion.3 However, the historical features of several disease processes may be similar. For example, the duration of pain in testicular torsion, epididymitis, orchitis, and torsion of a testicular appendage frequently overlap.7 Also, only 50% of patients with torsion have sudden onset of pain and about 20% of have pain associated with trauma or physical exertion, such as heavy lifting.8,9 Adding to the difficulty using the history is the fact that many young men do not provide an accurate history of trauma. The physical exam can be similarly misleading, because it is frequently limited by pain, edema, and patient compliance. In addition, findings such as absent cremasteric reflex, abnormal testicular lie (present in <50% of testicular torsion cases), and epididymal tenderness are not reliable in differentiating torsion from other causes of acute scrotal pain.10

The classic clinical features of epididymitis, such as dysuria and urethral discharge, are not consistent. Up to 50% of patients with acute epididymitis do not have dysuria or urethral discharge.4 Furthermore, many patients with epididymitis complain of acute onset of pain. This is probably due to poor recall or the need for a threshold of discomfort to be crossed prior to the patient's recognition of pain. Another complicating factor is that if the body or tail of the epididymis is inflamed without affecting the head, the pain and swelling will be in a different location from where most clinicians expect with epididymitis. Most clinicians learn to feel for the head of the epididymis on their physical examination and do not realize that it may not be involved. Patients with testicular torsion who are initially misdiagnosed with epididymitis are most commonly misdiagnosed because of the presence of dysuria, pyuria, or urethral discharge, or because of a vague history of pain onset, giving the impression of a less acute process.1 Because of the time-sensitive nature of testicular torsion, ultrasound is an ideal diagnostic test for the evaluation of testicular pain.

The clinical indications for point-of-care testicular ultrasound are as follows:

• Acute testicular pain
• Acute scrotal mass
• Trauma

Acute Testicular Pain

The most serious cause of acute testicular pain is testicular torsion. Testicular torsion can occur at any age; however, the majority of cases occur between 12 and 18 years of age. The most common underlying cause of testicular torsion is a congenital malformation known as bell clapper deformity, where the tunica vaginalis completely encircles the epididymis, spermatic cord, and testis instead of attaching to the posterolateral aspect of the testis. This allows the testicle to twist about its own axis compressing the vasculature and resulting in ischemia. The bell clapper deformity is most often found to be bilateral (50–80% of cases) upon surgical exploration.11 Further increasing the likelihood of testicular torsion is a history of an undescended testicle.12 Once blood flow is interrupted to the testicle, infarction and loss of the testicle can occur quickly. Testicular salvage rates are approximately 100% prior to 3 hours, 83–90% at 5 hours, 75% at 8 hours, and 50–70% at 10 hours. When a testicle has been torsed for longer than 10 hours, the rates of salvage decrease to 10–20%. After 24 hours, salvage of a testicle is rarely seen unless there has been intermittent detorsion.13 In general, urologists are reluctant to take patients to the operating room and explore a painful scrotum based solely on the clinical examination. Studies argue that such patients should not be routinely explored and that accurate diagnosis can be provided with Doppler ultrasound of the involved testicle.14

For the detection of acute testicular torsion, ultrasonography has a sensitivity of 80–98% and a specificity of 97–100%.15 Data regarding testicular ultrasound use by clinicians at the bedside are relatively limited.16–21 Testicular ultrasound carries a stigma of being a difficult and advanced level examination that will lead to dire consequences if misinterpreted, but the data do not support this notion. One study evaluated 36 patients with acute testicular pain who underwent point-of-care testicular ultrasound by an emergency physician, and demonstrated a sensitivity and specificity of 95% and 94%, respectively, for testicular torsion when surgical follow-up and radiology imaging were used as the criterion standard.16 All patients with testicular torsion were correctly identified. Other diagnoses found included epididymitis, orchitis, hemorrhage, and herniation. Another study demonstrated good accuracy of point-of-care ultrasound for a variety of testicular pathology encountered in the emergency setting.21

Patients at institutions without 24/7 radiology ultrasound capabilities will benefit the most from clinician-performed point-of-care testicular ultrasound. Also, when clinicians can quickly confirm lack of blood flow to a painful testicle they are more likely to attempt manual detorsion, which may significantly improve testicular salvage rates.

A major limitation for clinicians attempting to gain experience with testicular ultrasound is the infrequency of patients presenting with acute scrotal pain. However, one study demonstrated that testicular torsion could be easily simulated for training purposes by digital compression of the spermatic cord. This technique holds great promise as an educational tool that could quickly increase clinician confidence and expand the use of point-of-care testicular ultrasound.19

Acute Scrotal Mass

Painless scrotal masses are unlikely to represent an acute disease process. Patients often describe that the involved testicle has been slowly enlarging for some time, but they had simply ignored it or grew accustomed to the difference until some factor finally made them seek medical assistance. Firm, nontender testicular masses commonly represent neoplasms that should be directed for expeditious follow-up with a urologist. When the patient presents complaining of pain from the testicular mass, it may be from hemorrhage into the neoplasm itself. The vast majority of soft, nontender testicular masses are hydroceles that may develop because of a number of disease processes or idiopathically. Many are congenital and result from a direct communication with the abdominal cavity. Hydroceles may result from trauma, infection, neoplasm, radiation therapy, and undiagnosed torsion.22 Hernias can present with complaints of acute scrotal mass, and are generally painful. The presentation can be similar to that of torsion if the scrotum is erythematous.

Trauma

Blunt trauma can lead to injury of the testicle or associated structures. Assault, athletic injury (about 50% of blunt trauma cases), bicycle crashes, and motor vehicle crashes are the most common causes of blunt testicular trauma.23 Injuries can be in the form of laceration, hemorrhage, or contusion of the testicle. Clinical features of testicular injury are a tender swollen testicle, often accompanied by ecchymosis. Accurate diagnosis by physical examination alone is often difficult secondary to marked swelling and pain in the traumatized scrotum, thus making ultrasound imaging a requisite. The goal of point-of-care ultrasound in patients presenting with acute trauma to the scrotum is to determine whether the testicle is injured and requires operative intervention. Although a contusion or focal hemorrhage may simply require follow-up, fracture through the capsule of the testicle necessitates surgical intervention. Furthermore, since trauma can lead to testicular torsion, blood flow should be evaluated as well. Ultrasound is sensitive for detecting major trauma to the testicle and, therefore, can be useful for screening patients. While the accuracy of ultrasound is operator dependent, the diagnosis of a significant testicular injury is relatively straightforward.24,25

The scrotum is divided into two separate compartments by a midline septum called the median raphe. Each compartment of the scrotum contains a testis, epididymis, vas deferens, and spermatic cord. The normal adult testes are located in the scrotum and are oval in shape. Average testicular measurements obtained by ultrasound are 4 cm × 3 cm × 2.5 cm. Each adult testicle weighs between 10 and 19 grams. The size of the testicle changes with age; it increases in size up to puberty and decreases later in life. The testis is surrounded by a fibrous capsule known as tunica albuginea, which is covered by tunica vaginalis. The tunica vaginalis has two layers: the outer parietal and inner visceral, which merge at the posterolateral aspect of the testis (Figure 13-1). These two layers are separated by small amount of fluid. The tunica albuginea projects posteriorly into the testis to form an incomplete septum called mediastinum testis. Multiple septations arise from the tunica albuginea and run through the testicle. These septations result in the separation of the testicle into multiple lobules. The testicular parenchyma is made up of numerous seminiferous tubules that converge toward mediastinum testis and open into rete testis, which drains into the epididymal head.26,27

The epididymis is a tubular structure located along the posterolateral aspect of each testis. It measures approximately 6–7 cm in length and consists of a head, body, and tail. The head of the epididymis lies superolaterally to the testis, the body adjacent to the posterolateral margin of the testis, and the tail at the inferior pole of the testis. The tail of the epididymis turns into the vas deferens as it travels superiorly out of the scrotum. The vas deferens, in turn, travels in the spermatic cord. The spermatic cord contains a number of structures, including the testicular artery, cremasteric artery, deferential artery, pampiniform venous plexus, lymphatic structures, nerves, and vas deferens. The appendix testis and the appendix epididymis are found toward the superior pole of the testis. The appendix testis, an oval structure about 5 mm in length, usually lies in the groove between the testis and the epididymis. The appendix epididymis is attached to the head of the epididymis and is of the same approximate dimensions as the appendix testis. The appendix epididymis has been identified unilaterally in 34% and bilaterally in 12% of testes.26,27

Most of the arterial blood supply received by a testicle comes from the abdominal aorta through the testicular artery. A small portion of the arterial supply comes from the deferential and cremasteric arteries, which anastomose with the testicular artery. The deferential artery, arising from the vesicular artery, supplies the epididymis and the vas deferens. The epididymis, however, is supplied predominantly by the superior epididymal artery, which is a branch of the testicular artery. The cremasteric artery arises from the epigastric artery and supplies the peritesticular tissues. There is variability in normal anatomy and, in general, anything that appears abnormal should be compared to the contralateral side.26

Ensure patient comfort when performing a testicular ultrasound examination. The main issue is having the patient lay still when performing power and pulsed-wave Doppler measurements. Both of these modalities are very sensitive to motion artifact. Thus, provide adequate analgesia and reassurance. Explain the examination details and its goals to the patient. Disrobe the patient from the waist down and scan in the supine position. A frog leg position allows good access to the scrotum and it may help to prop pillows or blankets under each bent knee to allow relaxation of the legs. Place the scrotum in a sling and support it on a rolled towel placed between the patient's thighs to isolate the scrotum for scanning (Figure 13-2). Position the penis over the suprapubic region and cover it with a towel.

Place the ultrasound machine on the patient's right. Use a generous amount of warmed ultrasound gel. Cold gel may make the patient more uncomfortable by eliciting a cremasteric reflex. In cases of significant inflammation or torsion, activation of the cremasteric reflex may cause considerable pain. Cold gel can also result in contraction and thickening of the scrotal skin, making it difficult to see scrotal contents. When evaluating the testes, select a high-frequency (7.5–10 MHz) broadband linear transducer, or a 5.0 MHz transducer for large masses or very edematous scrotum (Figure 13-3). The resolution provided by high-frequency linear transducers is crucial for examining not only the parenchyma of the testicle but also the blood flow within it. Some clinicians will even utilize 12–15 MHz transducers to obtain the best Doppler resolution. This may not be possible if significant swelling exists and the testicle itself is several centimeters from the skin surface. Select a small part or testes preset on the machine. In addition to a high-resolution transducer, color, power and spectral Doppler modes are required when evaluating a patient for torsion. Power Doppler, a nondirectional version of color Doppler, is highly sensitive for detecting vessels with low blood flow, and its signal is independent of Doppler angle correction. The disadvantages of power Doppler are its susceptibility to motion and omission of directional information. Power Doppler is used for evaluating testicular perfusion, where blood flow tends to occur through relatively small diameter vessels and at lower speed. Knowing direction of blood flow is of little help in most cases of testicular ultrasound. Pulsed-wave Doppler is also an important component of the evaluation especially when incomplete torsion is present. It allows for documentation of both venous and arterial blood flow within the testicle.

Power Doppler activation will bring up a box-like window the size of which may or may not be adjustable (Figure 13-4). This box can be moved around the screen to the portion of the testicle or scrotum of interest. If the size of the power Doppler box or window is adjustable, it may or may not be helpful to enlarge it, so that it covers the entire testicle. The drawback of enlarging the color box is that this decreases the frame rate, which may make it more difficult to detect higher velocity arterial blood flow. Typically, a balance has to be achieved between a power Doppler window that is too small, requires frequent movement and does not capture the overall blood flow of the testicle, and a window that is too large and does not allow the machine to refresh the image frequently enough. Simply turning on the power Doppler box may not be adequate if the presets on the machine are not set correctly. Adjusting the sensitivity setting as low as possible without having power Doppler signal everywhere will allow for more accurate detection of blood flow.

Once reliable power Doppler signals are visualized in the unaffected testicle, use the pulsed-wave Doppler. A small gate, often two parallel lines, will appear on the screen (Figure 13-5). It is guided with a trackball or touch pad to the power Doppler signals inside the power Doppler box. Typically, an update button will have to be pushed (or the pulsed-wave button may have to be pushed a second time) when the parallel lines are placed over the power Doppler signal. Once activated, a tracing will appear showing the pulsed-wave Doppler signal. Adjust the size of the sampling gate, otherwise a poor waveform will be obtained. Turning up the pulsed-wave gain is acceptable to a point where the background around the graph baseline becomes brighter and shows some noise. This will allow the exam to be more sensitive for detecting pulsed-wave venous and arterial flow. Venous flow in the testis is typically continuous with minimal variation in velocity (Figure 13-6). Arterial flow to the testes has pulsativity, with a low-resistance, high-flow waveform pattern (Figure 13-7). Sampling should occur in multiple areas in the testicle. Once the settings have been properly adjusted on the unaffected side, move the transducer to the painful testicle. If the machine's settings are identical to those used for the unaffected testicle, the clinician will quickly appreciate if blood flow in the affected testicle is similar, decreased, or absent. In addition, gray scale comparison can quickly be made between the two testicles (Figure13-8). A side-by-side comparison of the two testes can be helpful and illustrates any difference in power Doppler blood flow or echogenicity in a single image

Scan the scrotum and its contents in two orthogonal planes, along the longitudinal and transverse axes. Scan the asymptomatic side first to familiarize the patient with the process; it also provides a comparison of sonographic anatomy and blood flow. Anchoring the scanning hand to patient's thigh will keep it from moving unintentionally. Scan the unaffected testicle in the longitudinal plane from medial to lateral (Figure 13-9A). At this point the indicator on the transducer is typically pointed toward the patient's torso; however, if the testicle has an oblique lie, it is appropriate to orient the indicator toward the upper pole of the testicle. Pay attention to the gray scale abnormalities such as edema, focal masses, or disruptions, and measure the length and thickness of the testes. Evaluate the epididymis in this view. In the long-axis view with the indicator directed cephalad, the epididymis is seen on the left side of the screen. Any epididymal abnormalities will often become evident on the longitudinal views. Turning transverse, still on the unaffected side, scan the testicle from top to bottom, again looking for any gray scale abnormalities (Figure 13-9B and 13-9C). Measure the width in the central portion of the testicle. Scan the spermatic cord from the inguinal canal to the posterosuperior aspect of the testes. After evaluating the testes, assess the scrotal skin thickness and the remaining scrotal contents. Adjust the gain, depth, and resolution settings as appropriate for optimal gray scale image acquisition.

Perform the Doppler examination after the gray scale evaluation of the scrotum to assess blood flow. Scan the asymptomatic side first to adjust Doppler settings to display low-flow velocities. Orient the transducer in the longitudinal plane of the testicle with the power Doppler feature turned on. Unless the machine presets happen to already be optimized for the testicular examination, some adjustments in gain, wall filter, scale, and pulse repetition frequency (PRF) will have to be made. Low wall filter (100 KHz), low PRF (1–2 Hz), and 70–90% color gain output settings are ideal for testicular scanning. The goal of these adjustments is to demonstrate as much blood flow as possible without introducing more than minimal artifact. Power Doppler is highly sensitive to any movement of the testicle or the clinician's hand. Once areas of power Doppler signal are visualized, appreciate the amount of blood flow in the testicle. With experience it will be obvious when there is too much blood flow, as in cases of inflammation, or too little blood flow, as in possible ischemia. Even in experienced hands, however, it is prudent to reserve judgment until the two sides can be compared, as long as the other testicle is present for comparison. At this point, activate the pulsed-wave Doppler and place its sampling gate over areas of power Doppler signal until both venous and arterial waveforms are obtained in multiple areas within the body of the testicle. Blood flow seen on the edge of the testicle may be misleading and should not be reassuring. After evaluating testicular perfusion, a complete ultrasound examination of the scrotum includes confirmation of epididymal blood flow using power Doppler and spectral Doppler waveform analysis. Quantification of outflow resistance can be accomplished by determining the resistive index (RI). RI is defined as the peak systolic velocity minus the end-diastolic velocity, divided by the peak-systolic velocity, and is easily calculated by the ultrasound machine's software.

Repeat the entire process on the affected side; however, the examination is typically not finished at this point. In the majority of cases, it is helpful to perform a transverse scan of both testes simultaneously to identify differences in size, echogenicity, and blood flow (Figure 13-10). With the transducer turned horizontal through the midportion of both testes and indicator toward the patient's right hip, scan the testes from upper to lower pole for comparison in gray scale. Turn on power Doppler to evaluate the testes. This will often mean enlarging the power Doppler box, thus slowing the motion on the screen. This view is ideal for demonstrating any similarities or differences between testes in both gray scale and power Doppler. This is especially illustrative in cases of torsion, with one side showing ample blood flow and the affected side showing no blood flow in the same power Doppler box (Figure 13-11A and 13-11B). Similarly, when one testicle has significantly increased blood flow due to inflammation and the other has normal blood flow, the diagnosis is difficult to dispute when such an image is obtained (Figure 13-12). Despite which order one chooses to perform the individual steps, perform the examination the same way each time for consistency.

Sonographically, a testicle has mid-gray or medium-level echoes and appears quite homogeneous in echotexture (Figure 13-13). The echogenicity of the testes is somewhat similar to liver and thyroid tissue. The normal scrotal wall thickness varies between 2 and 8 mm, depending on the state of contraction of the cremasteric muscle.26 The tunica albuginea is seen as one echogenic stripe encircling the testis. The epididymis can be readily differentiated from the rest of the testicle in normal as well as pathologic instances. It has similar echogenicity to the testicle but can appear slightly brighter. While the head of the epididymis is readily seen, the body (2–4 mm in diameter) and tail (2-5 mm in diameter) may be harder to differentiate when no inflammation is present. The mediastinum testis is seen as a linear echogenic band extending across the testes in a craniocaudal direction (Figure 13-14). The thickness and length of mediastinum testis are variable. Adjacent to the mediastinum testis, the normal rete testis is seen as a hypoechoic area with a striated configuration in approximately 18% of patients.26 The appendix testis (5 mm in length) is a small oval structure and is normally hidden by the epididymal head, thus making it nearly impossible to differentiate in normal examinations. On B-mode, the appendix testis appears isoechoic to the testis. If a hydrocele is present, the appendix testis often becomes outlined by the fluid and is seen as a defined structure (Figure 13-15). When torsed, it may cause not only local inflammation but also an epididymitis-like appearance due to diffuse inflammation of the epididymal head. The appendix testes may be located in different areas on the testicle. Additionally, the epididymis can have appendages. The appendix epididymis is approximately the same size as the appendix testis but is usually pedunculated and located at the head of the epididymis (Figure 13-16) Sonographically, the spermatic cord is seen as multiple hypoechoic linear structures in the long axis and circular hypoechoic structures in the transverse axis (Figure 13-17). The normal thickness of the spermatic cord in the inguinal canal is approximately 4 mm. The normal spectral waveform of the intratesticular arteries and arteries supplying the epididymis (deferential and cremasteric arteries) have a low-resistance, high-flow pattern. However, the arteries supplying the scrotal wall have a low-flow, high-resistance pattern. The RI of normal testicular artery ranges from 0.5 to 0.8.15

Epididymitis

Epididymitis is the most common cause of scrotal pain in adolescents and adults.28 The disease is insidious in nature; however, a significant proportion of patients present with sudden onset of pain mimicking testicular torsion. Infection of the epididymis or testicle usually results from retrograde spread of bacteria from the bladder or prostate via the vas deferens.28 Another disease process that can present with signs and symptoms of epididymitis in prepubertal males is torsion of the testicular appendage. In fact, it is believed that many cases of appendiceal torsion are misdiagnosed as epididymitis in prepubertal males.

The epididymal head is the most commonly affected region, but the entire epididymis may be involved in acute epididymitis. Infection usually starts in the head or tail of the epididymis, and then spreads to the entire epididymis and the testis. Comparison with the contralateral testis is crucial to make an accurate diagnosis. Sonographically, the affected epididymis appears enlarged, which is usually confirmed by comparing both the affected and unaffected sides (Figure 13-18). It will often have decreased echogenicity on standard B-mode examination due to associated edema. Although the epididymis is diffusely involved, focal inflammation of a region of the epididymis is seen in one-third of the patients leading to an area of well-defined swelling or enlargement. This is usually either the head or the body of the epididymis. Scrotal wall thickening is frequently seen, which is an indirect sign of inflammation. Epididymitis can cause accumulation of a reactive hydrocele similar to testicular torsion or torsion of the appendix testis. Thus, the presence of a small or moderate amount of fluid in the hemiscrotum is not a reliable sign for differentiating between the disease processes. In cases with isolated epididymitis, the testis looks normal on ultrasound.26

The sensitivity of color Doppler ultrasound in detecting scrotal inflammation is almost 100%.26 In the majority of cases, the color Doppler confirms the gray scale findings typical of acute epididymitis. However, in 20% of patients with epididymitis, the gray scale appearance of the epididymis is completely normal and the inflammation is only detected using color Doppler.29 Epididymal inflammation, either idiopathic or infectious, usually leads to increased blood flow that is easily noted on power Doppler when compared to the unaffected side (Figure 13-19). With Doppler technology, minimal blood flow is seen in the normal epididymis, and the detection of any significant vascularity in epididymis should be considered abnormal. It is important to realize that focusing on the head of the epididymis may cause novice operators to overlook the body and tail of the epididymis, which may be the site of isolated inflammation (Figure 13-20). The vas deferens may actually be inflamed first, before the epididymal tail, and would have markedly increased blood flow on power Doppler in its posterior location at the inferior pole of the testicle and epididymal tail. The tail of the epididymis can remain prominent after infection even with appropriate antibiotic therapy. Power Doppler should help differentiate between an acutely inflamed epididymal tail and a prominent leftover from previous infection. Spectral waveform analysis and RI can also provide additional information because epididymitis is associated with decreased vascular resistance compared with that seen in healthy men. The RI is rarely <0.5 in healthy individuals, but in >50% of patients with epididymo-orchitis, the RI is <0.5. Peak systolic velocity is increased in epididymal arteries, and use of a peak systolic velocity threshold of 15 cm/s results in a diagnostic accuracy of 93% for epididymitis.26 What clearly separates epididymitis from testicular torsion is the presence of increased blood flow in the testicle when compared to the contralateral side.

Orchitis

Orchitis is an acute infection of the testicle; most cases follow an initial episode of epididymitis.3 Isolated orchitis without epididymal involvement is rare and is usually viral in etiology. Testicular inflammation from mumps occurs in approximately 30% of cases and involvement is often bilateral. Orchitis develops in 20–40% of cases due to direct spread of infection from epididymis. It is usually diffuse. Patients present with a painful testicle must be differentiated from testicular torsion or other causes.

Sonographically, diffuse testicular involvement is usually seen as enlarged hypoechoic testicle due to edema, whereas a focal process usually manifests as multiple hypoechoic lesions. Other gray scale findings of orchitis include reactive hydrocele and scrotal skin thickening. In both orchitis and testicular torsion, inflammation and edema can lead to decreased echogenicity of the testis. B-mode ultrasound is not a reliable method to differentiate between orchitis and torsion unless torsion is advanced and prominent changes are noted. Power Doppler can assist in differentiating between the two diagnoses since testicular blood flow will increase as a result of inflammation (Figure 13-21). In approximately 40% of cases of orchitis, gray scale findings are normal and hyperemia on the color Doppler is the diagnostic finding.29 The inflammation and associated increase in blood flow seen on power Doppler may be regionalized, especially early in the process. Significant inflammation may be seen in one portion of the testicle (e.g., the inferior pole), but not in the rest of the testicle. The clinician should take time to investigate the areas without markedly increased blood flow to make sure that flow is not absent in these regions. Necrosis in one part of the testicle could lead to inflammation and increased flow in an adjacent portion, which should prompt a urologic consultation. In addition, an area of absent blood flow may be due to an abscess, which should also prompt a urologic consultation (Figure 13-22).

Spectral Doppler can provide additional diagnostic clues such as increased intratesticular peak systolic velocity, RI <0.5, and easily detectable and increased venous flow. The use of a peak systolic velocity threshold of 15 cm/s yields a diagnostic accuracy of 90% for orchitis.26

The increased blood flow of orchitis can mimic hyperemia seen after detorsion; if clinically suspicious, the clinician may simply rescan the patient in 15 minutes. The hyperemia from a recent detorsion should have resolved and the pain should also have resolved. Conversely, increased blood flow from orchitis will not resolve and pain will continue. Diffuse testicular hyperemia is also seen with infiltrative malignant diseases such as lymphoma and leukemia. In such cases, the clinical history can help differentiating infection from neoplasm. In cases with focal hypoechoic hypervascular lesion, involvement of the epididymis may distinguish the lesion from a testicular tumor. When focal lesions of heterogeneous echogenicity are diagnosed as epididymo-orchitis, a follow-up ultrasound examination after antibiotic treatment is recommended to confirm the resolution of the lesions so that other causes such as tumor, infarction, and metastasis can be ruled out. The complications of epididymo-orchitis include testicular infarction, scrotal abscess, pyocele, infertility, chronic pain, and atrophy.28

Testicular Torsion

Torsion more often affects the left testes than right due to the greater length of the spermatic cord on the left side.30 The sonographic findings of testicular torsion vary with the degree of rotation and duration of obstruction. The gray scale features of testicular torsion are summarized in Table 13-1. The gray scale findings are nonspecific for testicular torsion and may be subtle or absolutely normal early in the course of testicular torsion. The edema and change in echogenicity of testes and epididymis may take 6 hours to develop.15,30,31 Thus, always use Doppler to assess testicular perfusion. The Doppler features of testicular torsion are summarized in Table 13-2. When blood flow is absent or severely compromised in the affected testicle, the diagnosis of testicular torsion is clear. When the degree of flow is similar between the affected and comparison testicle, obtain pulsed-wave Doppler tracings to confirm both arterial and venous flow. Power Doppler alone should not assure the clinician that both venous and arterial flow are present. Additionally, the presence of arterial flow does not always exclude testicular torsion. The absence of a venous pattern by pulsed-wave Doppler on the affected side may be the only finding in early torsion. This is better understood by reviewing the mechanism of torsion and loss of blood supply to the testicle. During torsion, the testicle begins to twist around the axis of the spermatic cord. As the twisting progresses, venous flow is initially lost because of easily collapsible vessel walls in the low-pressure venous system. Venous obstruction is followed by a decrease in arterial inflow that eventually progresses to complete arterial obstruction. Thrombosis occurs in the arteries and veins and results in necrosis of testicular tissue. Experimental studies have shown that complete arterial occlusion occurs at about 450–540 degrees of torsion.32 Once the spermatic cord is fully torsed and no blood flow is present, the testicle takes on a diffusely edematous appearance (Figure 13-23), but this may take several hours to develop. The best way to diagnose complete torsion is to document the lack of power Doppler signal within the affected testicle (Figure 13-24).

Another abnormality that may be visualized in patients with testicular torsion is a spiral twisting of the spermatic cord above the level of the testicle. This may appear as a round or oval extratesticular mass at the level of the torsion. This finding is known as the whirlpool sign and has been described as having the appearance of a doughnut, a target with concentric rings, a snail, a snail shell, or a storm on a weather map.33 To detect this abnormality, advance the transducer proximally from the superior pole of the testicle and follow the incoming vessels up to the inguinal canal (Figure 13-25). When proceeding up the inguinal canal with the transducer oriented from the patient's feet to the head, the whirlpool mass may be seen (Figure 13-26). Adding power Doppler may show flow in blood vessels approaching the mass from the pelvis but no flow leaving the mass and heading toward the testicle. This confirms the diagnosis of torsion. Conversely, being able to trace cord vessels proximally into the inguinal canal and showing blood flow throughout their course help exclude the diagnosis of testicular torsion. The whirlpool sign is highly specific for testicular torsion; however, this finding can be misinterpreted as an enlarged epididymis and the patient can be misdiagnosed with epididymitis. Doppler can distinguish these entities by demonstrating decreased blood flow distal to a whirlpool mass and increased flow to the epididymis and testicle in cases of epididymitis.33

If the diagnosis is in doubt due to continued pain or if torsion–detorsion is suspected, performing serial point-of-care examinations is helpful. Closely following the blood flow can allow the practitioner to detect worsening torsion or the presence of torsion and detorsion in a patient who may otherwise have been sent home. Repeated color, power, and spectral Doppler examination could detect subtle progression of torsion in a patient with continued pain but with a normal initial exam. However, the presence of both venous and arterial blood flow in the testicle means it is not actively undergoing necrosis. Therefore, while continuing pain may be concerning, severe organ injury is not ongoing.

Torsion is not the only cause of testicular ischemia. Ischemia can result from spontaneous thrombosis of varicoceles or after corrective surgery. Severe edema following surgery or accidental vessel ligation during a vasectomy can also lead to vascular congestion and ischemia. The findings will be the same as in classic testicular torsion. A knot in the spermatic cord will not be identifiable in such cases.

Scrotal Trauma

Scrotal trauma may result in damage to both the testes and the extratesticular structures. Visualization of a normal testicle on ultrasound examination virtually excludes any significant injury. Since surgical intervention is required for rupture of a testicle, the clinician should have a heightened awareness for any abnormalities seen within the testicle on ultrasound. In these cases, further investigation or urology consultation is warranted. The timely diagnosis of testicular rupture based on ultrasound findings is critical because prompt surgical intervention results in salvage of the testis in 80–90% of rupture cases.23,34 Delayed diagnosis could result in ischemic necrosis of the testis, abscess, and loss of spermatogenesis. Ultrasound findings that suggest testicular rupture include focal areas of inhomogeneous echogenicity (Figure 13-27). These usually signal an area of hemorrhage or focal infarction. With larger hemorrhage, the testicle will lose its smooth contour (Figure 13-28). If the capsule of the testicle is intact, conservative treatment will often suffice. However, if discontinuity of the echogenic tunica albuginea is seen, then surgical intervention is required. A testicular fracture is seen as a linear hypoechoic band crossing the testicular parenchyma, which represents a break in the normal testicular architecture. In fewer than 20% of cases, actual fracture lines through the testes are seen.34 The fracture lines may or may not be associated with rupture of the testis, and the tunica albuginea may be intact. While the sensitivity and specificity for ultrasound detection of testicular fracture vary in multiple studies, it remains an excellent diagnostic modality to begin evaluating the severity of injury. An associated hematocele or testicular hematoma may be seen with the testicular fracture. Doppler is used to determine the integrity of vasculature. If normal flow is detected, testicular fractures are treated conservatively. Absence of flow on Doppler is suggestive of ischemia, and emergent surgery is indicated.23

Hematomas can involve the testis or extratesticular soft tissues such as the epididymis or the scrotal wall. The intratesticular hematomas are generally focal but can be multiple (Figure 13-29). The appearance of the hematoma within the testicle can vary depending on the age and size of the bleed. Acute hematomas appear inhomogeneously echogenic, but will later develop large anechoic regions within it. If the hematoma is large and involves entire testis, the testicular parenchyma has heterogeneous appearance. Doppler ultrasound can help assess the potential viability of the testis in these cases. Although gray scale sonography can occasionally confuse hematomas and tumors, the use of color Doppler may differentiate the two processes. Tumors are often hypervascular while hematomas will not reveal blood flow internally. A mixture of findings can occur when a patient hemorrhages into a testicular mass.

Testicular hematomas may be associated with a hematocele and scrotal wall injuries. Scrotal wall hematoma is seen as echogenic focal thickening of the wall with absent or decreased vascularity. Hematoceles are complex fluid collections within the potential space between the visceral and parietal layers of the tunica vaginalis. The appearance of hematocele varies depending on the length of time since the trauma occurred. Acute hematoceles are hyperechoic, and subacute and chronic hematoceles appear as complex fluid collections with loculations and septations (Figure 13-30). Hydroceles are also seen with scrotal trauma. Approximately 50% of acquired hydroceles are secondary to trauma.23,34

Testicular dislocation is a very rare condition after scrotal trauma. Dislocated testis can be found anywhere along a circle, the center of which is located in the external inguinal ring and the spermatic cord being the radius. The most common site reported is the superficial inguinal area, and other less common sites include the perineum, retrovesical, and acetabular regions. Ultrasound helps to exclude intratesticular injuries, and Doppler assessment confirms the viability of the testis. If the testis is viable, a manual reduction in the dislocated testis is recommended. If unsuccessful, emergent surgical reduction and fixation should be performed. Posttraumatic testicular torsion is a well-recognized entity, with an incidence of about 4–8%. The described mechanism of testicular torsion is a forceful contraction of cremasteric muscles. Perform color Doppler ultrasound assessment of testes to rule out torsion during scrotal injury evaluation.23,34

Fournier's Gangrene

Fournier's gangrene is another potential emergency that can present with acute scrotal pain and swelling. Fournier's gangrene is a rapidly progressing necrotizing fasciitis of the perineum and scrotum. It is a life-threatening polymicrobial infection that more commonly affects patients with impaired immune function.35,36 Fournier's gangrene may be diagnosed solely on clinical grounds in advanced stages, where morbidity and mortality are highest. Since early detection and treatment are essential for decreasing morbidity and mortality, early imaging modalities may be required to differentiate Fournier's gangrene from scrotal cellulitis. Any delay in differentiating Fournier's gangrene from cellulitis or idiopathic scrotal edema may increase morbidity and mortality.

Ultrasound can aid in the early diagnosis of Fournier's gangrene before it is apparent clinically. It can provide valuable clues to differentiate between Fournier's gangrene and a benign cellulitis. Subcutaneous air on plain radiographs is not universally present, especially early in the disease process. CT does not visualize the scrotal structures as well as ultrasound, but more accurately detects small amounts of subcutaneous gas and may reveal the underlying cause of Fournier's gangrene, such as a perianal abscess, fistulous tract, intraabdominal infectious process, or incarcerated inguinal hernia.37

Sonographic findings seen with early Fournier's gangrene include thickening of the scrotal skin and multiple hyperechoic foci with dirty shadowing within the scrotal wall, which is pathognomonic for Fournier's gangrene (Figure 13-31).20 The hyperechoic foci and associated dirty shadowing represent gas within the scrotal wall, not in the testicle. The presence of gas in the scrotal wall should not be confused with gas sometimes seen in herniated bowel in the scrotum. The characteristic gas pattern seen in Fournier's gangrene is parallel to the transducer face in the subcutaneous tissue of the scrotal wall. However, the gas visualized in the bowel lumen is located away from the scrotal wall and is not parallel to the transducer surface.37 The testes are rarely involved in Fournier's gangrene because the blood supply to the scrotum is different from that to the testes. Since Fournier's gangrene may result from prostatitis or orchitis, signs of epididymo-orchitis may also be seen.

Testicular Cysts

Simple testicular cysts are usually asymptomatic, nonpalpable, and found in the testicular parenchyma. These benign cysts are filled with clear serous fluid. The cysts are usually solitary, but they can be multiple and bilateral. They are associated with extratesticular spermatoceles and epididymal cysts. The causes of simple testicular cysts are trauma, surgery, and prior inflammation. Sonographically, they are thin-walled, well-defined, have good through transmission, and contain anechoic fluid with posterior acoustic enhancement (Figure 13-32). They vary in size from 2 mm to 2 cm and are generally located near the mediastinum testis in the upper half of the testis. Tunica albuginea cysts have a similar sonographic appearance but tend to be smaller and range in diameter from 2 to 5 mm. They are frequently found in older patients and brought to medical attention when a patient presents with a palpable testicular lump. The etiology of tunica albuginea cysts is unclear and is most often a result of trauma, hemorrhage, and infection. They are well-defined cysts located within the tunica at the upper anterior or lateral aspects of the testicle (Figure 13-33). They are generally solitary and unilocular but can be multiple or multilocular. Rarely, they can have a complex appearance mimicking a testicular neoplasm.27,38,39

Spermatocele/Epididymal Cyst

Spermatoceles are thought to result from cystic dilatations of the tubules of the efferent ductules and may be associated with a prior vasectomy. They are generally unilocular but can be multilocular. Sonographically, they are well-defined anechoic lesions measuring in size from subcentimeter to several centimeters, located within the head of the epididymis (Figure 13-34). They have low-level echoes with posterior acoustic enhancement. They are difficult to differentiate from epididymal cysts on ultrasound. Epididymal cysts are less common than spermatoceles. They contain clear serous fluid and arise throughout the length of the epididymis. An increased incidence of epididymal cysts was reported in boys who are exposed to diethylstilbestrol in utero (Figures 13-35 and 13-36). Both lesions are thought to be the result of prior episodes of epididymitis and trauma.11,27,39

Tubular Ectasia of Rete Testis

Tubular ectasia of rete testis is an anatomical variant that may be more commonly found because of improved resolution on new ultrasound equipment. The majority of cases occur in men older than 55 years of age and are associated with spermatoceles or epididymal cysts. It is generally associated with obstruction in the epididymis from prior inflammation or trauma. Sonographically, dilated rete testis appears as a collection of multiple small cysts or channels in the region of mediastinum testis (Figure 13-37). Power Doppler will reveal them to be avascular. These lesions are often bilateral but are frequently asymmetric. Dilated rete testis can be mistaken for testicular tumor.27

Hydrocele

There is a potential space between the visceral and parietal layers of the tunica vaginalis that can collect fluid, resulting in a hydrocele. A hydrocele is an abnormal collection of large amount of serous fluid in between the two layers of tunica vaginalis. It is the most commonly reported cause of painless scrotal swelling. Hydroceles are usually visualized in the anterolateral aspect of the scrotum and may be bilateral or unilateral. Their location is due to the attachment of the tunica to the testicle and scrotum posteriorly. Many hydroceles are congenital and result from a persistent communication between the scrotal sac and the abdominal cavity via a patent processus vaginalis. Acquired hydroceles can result from trauma, infection, neoplasm, surgery, radiation therapy, and undiagnosed torsion.22

Sonographically, a simple hydrocele appears as an anechoic or dark area surrounding the testicle (Figure 13-38). Occasionally low-level echoes are visualized secondary to high protein content or deposition of cholesterol crystals. Complex hydroceles can contain septations and loculations, especially when an inflammatory process is present. Most acute hydroceles that form in reaction to infection are thin walled. The collections of fluid seen as a result of trauma or torsion also tend to be small. Chronic hydroceles (hematocele or pyocele) that have developed slowly from a secondary process are larger and may have irregular septations, which reflect previous hemorrhage or infection. As in most cases with ultrasonography, blood cannot always be differentiated from serous fluid. A history of trauma, previously diagnosed neoplasm, or surgery would suggest a hematocele. Pyoceles are the result of untreated epididymo-orchitis or rupture of an intratesticular abscess into the potential space between the two layers of the tunica vaginalis. A large number of echoes with septations and loculations in the hydrocele may suggest the presence of pus in the proper clinical setting (Figure 13-39).8,26–28

Varicocele

Varicocele represents abnormal dilation and tortuosity of the veins in the pampiniform plexus located in the spermatic cord. There are two types of varicoceles: primary (idiopathic) and secondary (acquired). Idiopathic varicocele is believed to be caused by incompetent valves in the internal spermatic vein, which results in retrograde flow of blood into pampiniform plexus. Nearly 99% of idiopathic varicoceles are left-sided but they can present bilaterally.20 The spermatic vein on the right drains directly into the inferior vena cava. The left spermatic vein first drains into the left renal vein at nearly a 90° angle. The left-sided predominance of varicoceles is due to the greater length of the left internal spermatic vein in comparison with the right and increased venous pressure on the left side caused by the junction of the left internal spermatic vein with the left renal vein at a right angle. Secondary varicoceles are due to increased pressure on the spermatic vein caused by various disease processes such as hydronephrosis, cirrhosis, or a mass in the abdomen or retroperitoneal space. Secondary varicoceles may also occur with thrombosis of the inferior vena cava and in the nutcracker phenomenon, which is characterized by compression of the left renal vein in the fork between the abdominal aorta and proximal superior mesenteric artery that leads to retrograde blood flow from the left renal vein into the internal spermatic vein causing varicocele.40 A right-sided varicocele, non-decompressible varicocele, and a newly discovered varicocele in a patient older than 40 years should prompt an investigation for a neoplasm. In men over 40 years of age, a non-decompressible varicocele is classically caused by a renal malignancy invading the renal vein.

Patients usually present with a palpable scrotal mass, dull scrotal pain, or discomfort or feeling of heaviness. Perform ultrasound assessment with the patient in both a supine and a standing position. Varicocele becomes more noticeable in the standing position and when the patient performs a Valsalva maneuver. Normally, the diameter of veins of the pampiniform plexus veins range from 0.5 to 1.5 mm. Gray scale findings include multiple, hypoechoic, serpiginous, tubular structures with diameters exceeding 2 mm that are usually best seen superior and lateral to the testis (Figures 13-40 and 13-41). Color Doppler ultrasound is almost 100% sensitive and specific in diagnosing varicocele.26 The addition of power Doppler, especially with a concomitant Valsalva maneuver, will demonstrate blood flow in the characteristic pattern (Figure 13-42). Doppler will reveal a phasic venous blood flow pattern and retrograde filling with Valsalva maneuver. Varicoceles increase in size and show increased color Doppler flow with the patient in standing position.

Occasionally, varicoceles may be confused with inflammation of the epididymal tail or bowel content in the scrotum. Having the patient perform a Valsalva maneuver should cause distention of the varices, and an obvious increase in blood flow through the venous structures. On rare occasions, a varicocele may be seen extending into the testicle itself. It can be followed from its origin to differentiate it from other pathologic processes.

Herniation

Herniation of abdominal contents into the scrotum may cause acute scrotal pain. The clinical presentation may simulate testicular torsion, epididymitis, or orchitis. Ultrasound is especially helpful in patients with equivocal clinical findings. To identify a hernia, it may not be sufficient to just scan patients in the supine position. It may help to increase intra-abdominal pressure with a Valsalva maneuver. Ultrasound can help identify the testes and often allows the examiner to visualize abdominal contents (Figure 13-43). Occasionally, a fluid or air-filled loop of bowel can be clearly visualized. In other cases, artifacts from bowel gas may be the only sign of a hernia. It is critical not to confuse Fournier's gangrene with bowel gas in a hernia. The viability of a bowel segment within the hernia sac can be grossly assessed with ultrasound. Obvious peristalsis typically means that the bowel has not yet infarcted. An akinetic dilated loop of bowel has high sensitivity (90%) and specificity (93%) for bowel strangulation.26 Clinicians should be aware of the possibility of contraction of the Dartos mimicking peristalsis. Also, power Doppler identification of blood flow in the bowel wall suggests viability. Absence of peristalsis, edematous bowel wall, and lack of blood flow on power Doppler suggest infarction. Increased power Doppler flow (hyperemia) may be seen in the early stages of strangulation. Omental fat can also be herniated into the scrotum and become strangulated. Sonographically, omental fat is seen as a complex echogenic paratesticular mass in the hernia sac. In addition, testicular ischemia can occur due to vascular compression from a hernia. Manipulation of hernia contents may result in compression of vascular structures within the inguinal canal. Consider post-reduction testicular ultrasound when patients have ongoing pain after reduction in an inguinal hernia.41

Testicular Tumors

The incidence of testicular tumors in prepubertal boys is estimated at 0.5–2.0 cases per 100,000. Most patients present with a painless scrotal swelling. Testicular tumors are uncommon causes of acute painful scrotum. Approximately 10% of the patients present with acute scrotal pain due to hemorrhage into the tumor or necrosis of the tumor. This acute presentation may mimic testicular torsion or epididymo-orchitis. The majority (95%) of the testicular tumors are germ cell neoplasms.42 Seminoma accounts for approximately 50% of these cases. In most cases, patients with testicular tumors need early urologic follow-up, not an emergent procedure. However, if a large intratumoral hemorrhage is detected, then immediate urologic consultation is prudent. Patients who present with large painless testicular masses that may have been developing for years require careful consideration prior to discharge (Figure 13-44).

The sensitivity of ultrasound for detecting testicular tumors approaches 100%. Sonographically, testicular tumors appear as focal or diffuse areas of hypoechogenicity in enlarged testicles. An area of heterogeneous echogenicity is suggestive of intratumoral hemorrhage and necrosis. Calcifications and cysts may also be found. Color Doppler imaging of suspected tumors is unreliable since the hypervascularity detected in testicular tumors is not distinguishable from the hypervascularity seen in testicular inflammation. The absence of enlargement of epididymis and edema of scrotal skin should favor the diagnosis of a tumor rather than an inflammatory process.

Torsion of the Appendix Testis

The appendix testis is a remnant of the paramesonephric duct. Torsion of the appendix testis is the most common cause of acute scrotal pain in children before puberty. In the pediatric population, appendiceal torsion is nearly as common as testicular torsion, accounting for 20–40% of acute scrotal pain cases.28,29 It is more frequently seen on the left side. Torsion of the appendix testis can present with similar symptoms to testicular torsion, but is often noted in a younger age group. It is important to distinguish appendicial torsion from testicular torsion because appendicial torsion is a self-limiting condition and does not require surgery. The sensitivity of ultrasound for the detection of appendiceal torsion is approximately 90%. Sonographically, the torsed appendix is visualized as a small hyper- or hypoechoic mass adjacent to the superior aspect of the testis or epididymis, depending on the evolution time. The testicular appendage larger than 5.6 mm is suggestive of torsion. Color Doppler demonstrates no internal blood flow in a torsed testicular appendage, and marked hyperemia in the adjacent tissues and diffusely throughout the testis and epididymis (Figure 13-45). Other ultrasound findings include reactive hydrocele, enlarged epididymal head, and scrotal skin edema.28,29

Calcifications

Calcifications in the scrotum are most often in the testicle or tunica albuginea, or within a hydrocele. “Scrotal pearls” are mobile hyperechoic calculi within a hydrocele resulting in a discrete acoustic shadow. These calcified bodies are the result of inflammation of the tunica vaginalis testis, hematoma, or torsion of the appendix testis or the epididymis. Scrotal pearls are usually of no clinical significance and no further workup is warranted. Small testicular calcifications are known as microlithiasis (Figure 13-46). Testicular microlithiasis refers to the presence of multiple nonshadowing echogenic foci that are 1–3 mm in size within the testicular parenchyma. The presence of five or more echogenic foci per transducer field in one testis is considered abnormal.26,43 These echogenic foci represent calcified hydroxyapatite concretions within the lumen of the seminiferous tubules. Most are discovered incidentally by ultrasound examinations done for symptoms such as pain, swelling, trauma, varicocele, hydrocele, or infertility.26,43 Testicular microlithiasis is usually benign, but it is found in 50% of patients with germ cell neoplasms, and the significance of this association is unclear.

Undescended Testicle

Patients may occasionally present with scrotal pain and are found to have only one testicle. While there can be congenital or surgically related absence of a testicle, it may be worthwhile to check for an undescended testicle, even in young adults. An undescended testicle may increase the risk of both infertility and testicular cancer. It is associated with a 50-fold increased risk of testicular cancer. Additionally, there is a 10-fold increase in the incidence of torsion of an undescended testis.30 Some patients may not be aware that one testicle has not descended. The majority (80%) of undescended testes lie within the inguinal canal and are often (25%) bilateral. Ultrasound has an accuracy of approximately 90% for localizing the undescended testicle. The undescended testis is frequently small and hypoechoic, and it might be difficult to differentiate from a lymph node. Assess blood flow since the risk of torsion is high in patients with painful undescended testicles (Figures 13-47 and 13-48).27

1. Contraindication. There are no absolute contraindications to evaluating the testicle with ultrasound. Examinations may be limited by pain, and analgesia will occasionally be required. Since minimal pressure is applied during the evaluation of the acute testicle, damage to a fractured testicle is not a concern.

2. Neonates and prepubescent boys. Testicular blood flow in prepubescent boys and neonates can be very difficult to detect, which may lead to inaccurate diagnoses. Doppler can demonstrate blood flow in only 32% of pediatric patients with a testicular volume <1 mL. In neonates, it is difficult to detect blood flow in about 10% of normal testes.30 It may require very sensitive equipment and considerable expertise to evaluate prepubescent testes.

3. Incomplete torsion. Complete torsion occurs at approximately 450° of twisting of the spermatic cord. Venous flow initially disappears followed by arterial blood flow. The presence of blood flow on Doppler only excludes complete testicular torsion. The sonographic findings of incomplete torsion may be subtle and careful comparison between the two sides is important to exclude incomplete or partial torsion. Diagnosing torsion early, when it is incomplete, can be challenging with color Doppler alone, as this method relies on subtle differences between the testes. The use of spectral Doppler to document both venous and arterial waveforms is optimal. The spectral Doppler findings suggestive of partial torsion are summarized in Table 13-3. The whirlpool sign, ipsilateral hydrocele, and scrotal thickening may also be found. If the suspicion for torsion is high and the initial ultrasound is normal, serial point-of-care ultrasound examinations should be considered.15,30,31

4. Intermittent torsion. A history of intermittent episodes of testicular pain that resolve spontaneously is highly suggestive of intermittent testicular torsion and detorsion. Approximately 50% of patients presenting with acute testicular torsion report previous episodes of recurrent scrotal pain. Ultrasound may not always be helpful since torsion may resolve before imaging is performed and ultrasound may show normal appearing testes. Unfortunately, intermittent testicular torsion can result in testicular damage seen histologically as peritubular fibrosis, atrophic seminiferous tubules, and decreased spermatogenesis. If this clinical entity is suspected, a urology consultation and orchiopexy is recommended in the near future before another acute event occurs. Approximately 10% of patients with history of intermittent torsion develop acute testicular torsion while waiting for orchiopexy.15,30,31

5. Postischemic hyperemia/Torsion–detorsion. Some patients may exhibit torsion and spontaneous detorsion. This entity can make for a challenging diagnosis if the ultrasound examination is performed during a period of detorsion. Shortly after detorsion, compensatory postischemic hyperemia may be detected as increased blood flow in the affected testicle (Figure 13-49). This can be confused with epididymo-orchitis. This paradoxical increase in blood flow will usually not last much longer than 15 minutes and returns to normal again at the site of detorsion. Point-of-care ultrasonography may be helpful in this setting because it allows for serial examinations. With the clinical acumen to observe the patient and perform serial ultrasound examinations, clinicians should be able to avoid this pitfall.15,30,31

6. Striated testis. With the aid of modern high-resolution equipment, providers are more likely than ever to see details of testicular structure not previously noted on ultrasound. In fact, the technological advances in imaging have created dilemmas, in which differentiation between normal anatomic variants and pathologic conditions can become challenging. One such example is striated testes, which presents as multiple hypoechoic linear bands radiating within the testis perpendicular to its long axis, similar in orientation to the testicular interlobar fibrous septae (Figure 13-50). Striated testes are most likely the result of interstitial fibrosis in asymptomatic older men and require no further evaluation. However, the differential diagnosis of striated testes also includes neoplasm, infection, infarction, and trauma. Narrowing the differential diagnoses depends on clinical presentation (age, history of malignancy, palpable testicular mass), and additional sonographic findings such as size of the testicle, focal mass, and Doppler abnormalities. In the absence of risk factors, relevant clinical findings, and Doppler abnormalities, a striated testicle is of no clinical significance. It is most likely due to fibrosis from aging or prior infection and probably needs no further follow-up.44

Case 1

Patient Presentation

A 21-year-old man presented to the ED with a complaint of right testicular pain. He stated that the pain started suddenly 5 hours prior to presentation. Since then, he also noted some swelling on the right side. The patient denied being sexually active but did note being struck in the genitals the day before during a basketball game. He had an unremarkable medical history and did not smoke. The patient denied any history of sexually transmitted diseases and stated he was not having any urinary symptoms or urethral discharge.

Physical examination revealed a healthy young male in mild distress with normal vital signs. The abdominal examination was unremarkable, with no obvious hernias or costovertebral angle tenderness. Testicular examination revealed an erythematous right hemiscrotum with moderate swelling. The right testicle was enlarged and painful to the touch. The epididymis was tender and slightly enlarged on examination. The right testicle had a horizontal lie and the cremasteric reflex could not be elicited. The left testicle was normal size and nontender to palpation.

Management Course

A urinalysis was normal. No urology service was available and a tertiary care hospital was approximately 90 minutes away by ambulance. Point-of-care emergency ultrasonography was available to the emergency physician. She performed an examination of the scrotum, noting enlargement and greatly increased blood flow to the right testicle and epididymis, with the epididymis twice the width compared to the contralateral side. A diagnosis of epididymitis with orchitis was made and the patient was discharged home with antibiotics, analgesics, and close follow-up and return instructions.

Commentary

Case 1 represents an example of the nonspecific signs, symptoms, and history that may be associated with the presentation of acute scrotal pain. The patient acutely became aware of testicular discomfort and swelling, although the disease process was probably slower in onset. The history of minor testicular trauma was coincidental, but could not be ignored. The physical examination is often less helpful than described in many textbooks, especially when orchitis is present and the entire testicle is tender and swollen. Without the availability of point-of-care ultrasound, the emergency physician would have had to transfer the patient. If a lack of blood flow was seen in the testicle, arrangements could have been made for immediate transfer to a urology consultant and manual detorsion could have been attempted. In this case, Doppler ultrasound showed increased blood flow to the testicle and epididymis, which is consistent with orchitis and epididymitis. An unnecessary transfer was avoided and the patient was discharged home with appropriate treatment and follow-up instructions.

Case 2

Patient Presentation

An 18-year-old man presented to the ED 3 days after being kicked in the groin during a soccer match. The patient was seen at an outside facility shortly after the injury at which time an evaluation, including an ultrasound examination, revealed a small-to-moderate-sized area of hemorrhage and no rupture through the testicular capsule. The patient was evaluated by an urologist and discharged home. He presents today because of increased swelling of the testicle. The scrotal skin is firm and erythematous, according to the mother, who is a pediatrician. The hydrocodone the patient was prescribed no longer relieves his pain. He denies any hematuria or other urinary symptoms.

Physical examination revealed an uncomfortable appearing male with normal vital signs. The cardiac, lung, and abdominal examinations were normal. Testicular examination revealed an enlarged and erythematous left hemiscrotum that was markedly tender to palpation. The testicle was clearly enlarged but difficult to differentiate within the scrotum. The contralateral testicle was nontender and appeared to be of normal size. A urinalysis was normal. The mother insisted that something had changed since his injury; however, when she contacted the urologist, he suggested a follow-up appointment in 2 days and recommended increasing the patient's analgesic dose.

Management Course

An ultrasound examination in the medical imaging department was not available after hours. The emergency physician performed a point-of-care ultrasound examination, and this revealed a large heterogeneous testicle with areas of acute and old hemorrhage. Normal color Doppler flow was present in the portion of the testicle that appeared normal. A fracture line could be defined through the parenchyma of the testicle and appeared to go through the capsule of the testicle. The urologist on call was contacted. After a brief evaluation and review of the point-of-care ultrasound examination clips, the patient was taken to the operating room for scrotal exploration. Exploration revealed several areas of hemorrhage and a testicular rupture that were repaired. The patient was admitted overnight. Follow-up showed slow resolution of the injury with 80% function of the testicle at 30 days. No further surgical intervention was required.

Commentary

Case 2 illustrates the utility of ultrasound in defining testicular anatomy. The patient had already been scanned 3 days ago and no severe pathology was noted. However, he bled more into the testicle and a fracture line going through the capsule was better defined on reexamination. The patient had findings that led directly to operative intervention. It would have been tempting to simply discharge him home for follow-up with his urologist as planned. Point-of-care ultrasound helped the patient avoid ongoing pain and further disability.

Case 3

Patient Presentation

A 34-year-old man presented to the ED, complaining of left scrotal pain. The patient noted awaking with severe pain approximately 6 hours prior to the admission. His medical history was remarkable for recent surgery to “fix” some varicoceles that had been causing him pain for years. He complained of scrotal pain, which was different from the incisional pain.

Physical examination revealed an afebrile patient in moderate distress. Examination of the abdomen was unremarkable. The GU examination showed a slightly erythematous scrotum, more prominent on the left. There was moderate swelling of the left testicle and it was exquisitely tender. It had a normal lie and the epididymis could not be reliably palpated. The cremasteric reflex was elicited with difficulty bilaterally. There was no evidence of infection at the incision site.

Management Course

A urinalysis showed three RBCs per high-powered field and five WBCs per high-powered field. No bacteria were seen. An ultrasound examination performed by the emergency physician revealed the right testicle to have normal echotexture, size, and blood flow. The left testicle was found to be moderately enlarged and appeared less echogenic than the unaffected testicle. The right testicle had normal blood flow with color and power Doppler imaging. No blood flow was seen within the left testicle with either color or power Doppler. The on-call urologist was consulted and immediately took the patient for surgical exploration of the scrotum. He was found to have an ischemic left testicle as a result of diffuse thrombosis of veins in the spermatic cord with resultant vascular congestion.

Commentary

This case illustrates the difficulty in making a diagnosis of testicular ischemia without imaging in patients with scrotal pain. Clinicians who use point-of-care ultrasound are likely to make more accurate and confident diagnoses.

The author gratefully acknowledges the contributions of Michael Blaivas, who authored this chapter in the previous edition.