Diagnostic value of contrast-enhanced ultrasound (CEUS) and comparison with color Doppler ultrasound and magnetic resonance in a case of scrotal trauma

Abstract

Intratesticular hematoma is one of the most frequent presentations of scrotal trauma. Ultrasound is the first-line imaging modality in the evaluation of scrotal trauma, and its findings are crucial for the choice of treatment. An intratesticular hematoma may represent a diagnostic pitfall for the investigating physician since its appearance may mimic other conditions, such as testicular neoplasms or segmental infarction. Although the gold standard imaging modality for the characterization of a testicular lesion is contrast-enhanced magnetic resonance (MR), MR equipment is not always available in an emergency department. Contrast-enhanced ultrasound (CEUS) may represent a valid and cheaper alternative compared with MR, which may aid the physician in the differential diagnosis. We describe the case of a 19-year-old male with a scrotal trauma following a motorcycle crash. In accordance with the literature, we carried out a contrast-medium whole-body computed tomography for the evaluation of any potential traumatic injury. Because of scrotal swelling and the patient complaining about pain in the right testicle, we performed a scrotal ultrasound, which demonstrated an enlarged right testicle, with an inhomogeneous echostructure due to the presence of a hypoechoic area in the middle and upper portion of the testicle. Color Doppler ultrasound did not show signals of intralesional vascularization. The lesion, although having characteristics compatible with hematoma, must not be diagnosed as testicular neoplasia, segmental infarction, or other mimics. For more information, a CEUS examination was performed. The examination clearly showed the extent of the lesion, the integrity of the testicular capsule, and the absence of internal vascularization; all these findings were regarded as indicators of a testicular hematoma. After the urological examination, the patient was prescribed antibiotic therapy and bed rest. For further confirmation of the CEUS examination, an MR was performed 2 days later, showing a perfect correspondence with the CEUS findings. Our case demonstrates that CEUS is a faster, cheaper, and valid alternative to MR in an emergency setting, as in testicular trauma, in which the hematoma may mimic conditions (neoplasm) that require a different treatment.

Introduction

Scrotal trauma constitutes about 1% of all traumatic injuries. The mobility of the scrotum and its anatomical location are protective factors. The highest incidence of scrotal trauma is observed between 10 and 30 years of age; blunt trauma is the most common mechanism of injury, usually resulting from athletic injury or motor vehicle collision. Penetrating trauma, thermal injuries, and degloving injuries are less common [1–4].

Ultrasound with color Doppler is the first-line imaging modality for studying traumatic pathology of the scrotum, and its findings are crucial for the choice of treatment. The key point is to identify whether the tunica albuginea is ruptured. In this case or if there are signs of ischemia, surgical repair must be performed as soon as possible to prevent irreversible damage. Testicular hematoma is one of the most frequent presentations of scrotal trauma.

Hematomas are usually focal and hyperechoic in recent bleeding, and their echogenicity decreases with time; these lesions have no vascularity [5–9]. In some cases, the differential diagnosis between hematoma and neoplasm may be difficult [10, 11]; in these cases, contrast-enhanced magnetic resonance (MR) is the gold standard imaging modality for characterizing a testicular lesion, but MR equipment is not always available in an emergency department.

Contrast-enhanced ultrasound (CEUS) is a well-established technique in the study of traumatic lesions of solid abdominal organs [12–15]. In recent literature reports, CEUS has proven to increase the examiner’s diagnostic confidence in the setting of blunt scrotal trauma [16–19].

Case report

We describe the case of a 19-year-old male who presented, during the night, to our emergency department after a motorcycle collision. He presented with low abdominal and scrotal pain, a cutaneous wound in the right pubic region, and scrotal swelling. Blood tests and e-FAST (extended focused assessment with sonography in trauma) were normal. He underwent contrast-medium whole-body computed tomography (CT) for trauma staging of any potential traumatic injury, but no injuries were reported.

The morning of the next day, because of persistent scrotal pain and swelling, he underwent a scrotal ultrasound, which showed an enlarged right testicle with in the middle and upper portion a mildly hypoechoic, ill-defined area. With color Doppler (15–4 MHz linear array transducers, MyLab™Eight, Esaote SpA, Italy), the damaged area was better defined: The area had no vascular signals, the evaluation of the testicular capsule in the damaged area was not clear, and the lower pole of the testicle had a homogeneous structure and color signal (Fig. 1).

Fig. 1.

Traumatic right testicle lesion. a, b Baseline axial and longitudinal view ultrasound show an ill-defined area of inhomogeneity in the echostructure of the right testicle. c, d Color Doppler images of the right testis (c slightly more axial than d) show a heterogeneous, mainly hypoechoic focus with ill-defined margins and no color Doppler spots inside

Retrospectively examining the CT images, we found that there were some indications for testicular injury, such as the small amount of fluid collection in the right scrotal sac and the not well-defined upper profile of the right testicle, but they were overlooked at CT (Fig. 2).

Fig. 2.

a, b Axially and sagittally reformatted CT scans show a small amount of fluid collection in the right scrotal sac (white arrow in a) and the not well-defined upper profile of the right testicle (white arrowhead in b)

Because MR was not immediately available, we decided to perform CEUS to assess the exact extension of the lesion, the integrity or the damage of the capsule, and the vascular pattern of the lesion.

The evaluation with CEUS was carried out using a linear probe (15–4 MHz linear array transducers, low mechanical index imaging, MyLab™Eight, Esaote SpA, Italy). The contrast-medium consists of microbubbles of a gas, sulfur hexafluoride, surrounded by a shell (SonoVue™ 5.0 mL, Bracco SpA, Milan, Italy). The medium is injected intravenously, and the gas is eliminated by breathing after the rupture of the microbubbles. After approximately 20 s, the microbubbles reach the intravascular space of the testis and may be visualized up to 2–3 min after administration, and then the intensity progressively decreases [20].

The CEUS examination better showed an avascular area in the middle and upper portion of the right testis (Fig. 3), which corresponded to the hypoechoic area identified at conventional ultrasound. The remaining portion of the testis and the contralateral testis were normal. This lack of contrast enhancement is typical of nonvascularized tissues and suggested the diagnosis of testicular hematoma. The CEUS also clearly demonstrated the integrity of the testicular capsule, which was a fundamental finding that changed the patient’s management.

Fig. 3.

a, b CEUS of the right testis (transverse scan on the left, sagittal scan on the right) confirms the presence of a focal alteration that corresponds to the area identified by the grayscale and Doppler ultrasound. CEUS better defines the site and the extent of laceration, showing the absence of vascularization in the injured area and the integrity of the capsule (arrows)

An MR was performed 2 days later, showing a perfect correspondence with the CEUS findings (Fig. 4). The presence of an avascular area, as well as foci of hemoglobin degradation products, was consistent with the diagnosis of hematoma.

Fig. 4.

a Unenhanced axial T1 TSE, b, c axial and sagittal T2 TSE, d axial unenhanced fat-suppressed T1 GRE, e postcontrast sagittal T1 with fat suppression, and f postcontrast axial T1 showing an inhomogeneous avascular area in the right testis (white arrow), corresponding to the alteration identified at CEUS. The inhomogeneous T2 signal is due to the presence of a hyperacute and acute hemorrhage. The orange arrowhead in d indicates foci of hyperintensity in a T1-weighted, fat-suppressed image, suggestive of methemoglobin deposits. The lesion was diagnosed as a hematoma

The patient was treated conservatively. Four months later, the patient underwent a follow-up sonographic examination. Color Doppler evaluation showed a decrease in size of the hypoechoic area, with no Doppler signal inside (Fig. 5); these findings were highly consistent with the diagnosis of hematoma.

Fig. 5.

Four-month follow-up ultrasound showing a decrease in size of the hypoechoic area in the right testis (white arrowheads, compare with Figs. 1 and 3). This finding definitely excludes neoplasm and supports the diagnosis of intratesticular hematoma

Discussion

The illustrated case is an example of how CEUS can aid the examining physician in cases of doubtful testicular lesions.

In the case of a testicular traumatic lesion, it is essential that the examiner, in a short time, gives information about both the nature and the extent of the lesion, which is, in any case, a different diagnosis from the occasional diagnosis of testicular neoplasia. As a matter of fact, the literature reports cases of testicular hematoma mimicking a seminoma [10, 11]. Seminomas are usually hypoechoic compared with the background testis. They tend to be homogeneous and may be lobulated or multinodular. With Doppler ultrasound, a seminoma usually demonstrates increased vascularity [10].

Moreover, other focal testicular lesions may widen the differential diagnosis. Acute segmental testicular infarction may be identified as a complication of acute orchitis or orchiepididymitis but may also be idiopathic or encountered in testicular torsion, hypercoagulation conditions, vasculitis, or trauma. Infarction presents as one or more avascular areas separated by normal vessels, consistent with ischemic testicular lobules, which are wedge shaped (with the apex located in the mediastinum testis) or round shaped. CEUS may very well depict a perilesional rim enhancement and centripetal vessels arising from the capsule [16, 17]. In our case, the shape of the lesion, its homogeneity at CEUS examination, and the detection of hemoglobin products with MR made the diagnosis of hematoma more likely than that of testicular segmental infarction.

Orchitis may present with foci of localized hypoechogenicity but it shows increased vascularity at color Doppler. An epidermoid cyst has a typical “onion ring appearance”. Other malignant tumors, such as nonseminomatous germ cell tumors, lymphoma, and metastasis, show increased vascularization and do not decrease in size at follow-up studies.

Besides the nature of the lesion, it is important to clarify whether the testicular capsule is intact or damaged because this changes the management of the patient from nonoperative to operative treatment.

In our case, color Doppler evaluation added more information compared with baseline ultrasound, but still some doubts remained about the real extension of the lesion, the evaluation of the capsule, and the possibility of the presence of a neoplastic lesion.

Even though the patient had a history of trauma (which could help in the differential diagnosis), the imaging findings could not completely exclude malignancy.

CEUS showed the extension of the lesion, the integrity of the capsule, and the complete absence of vascularity in the lesion, making the hypothesis of benign alteration highly probable, particularly supporting the hypothesis of hematoma.

MR supported the diagnosis, which was already suggested with a less expensive and faster imaging modality. Follow-up ultrasound further increased the confidence in the diagnosis of hematoma.

Like the cases reported by Bertolotto et al. [17] and Valentino et al. [19], our case demonstrates how CEUS may provide additional information in the setting of scrotal trauma that is not provided by conventional and color Doppler ultrasound.

Moreover, the current literature suggests that CEUS is superior to conventional ultrasound not only in the characterization of a mass but also in the identification of the extension of corpuscular fluid collections and in the diagnosis of testicular fractures and rupture with interruption of the tunica albuginea [16–19].

A flowchart for the use of CEUS in blunt scrotal trauma is proposed in Fig. 6.

Fig. 6.

Proposed diagnostic flowchart for patients with blunt scrotal trauma. CEUS contrast-enhanced ultrasound, MR magnetic resonance

Conclusions

Although there are still no definite indications for the use of CEUS in acute scrotal disease [20–22], our case, along with reports from the literature, suggests that this imaging modality may increase the examiner’s confidence in the diagnostic workup of blunt scrotal trauma.

Because most emergency departments lack MR equipment, CEUS may be proposed as a valid alternative to MR in those cases in which baseline ultrasound and color Doppler ultrasound remain ambiguous, especially in infarction, trauma, testicular torsion, and the characterization of testicular masses.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.