Diagnostic Ultrasound - Abdomen and Pelvis
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Diagnostic Ultrasound - Abdomen and Pelvis

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PART II SECTION 10 Scrotum Introduction and Overview Approach to Scrotal Sonography 680 Testicular Germ Cell Tumors 682 Gonadal Stromal Tumors, Testis 686 Testicular Lymphoma/Leukemia 690 Epidermoid Cyst 692 Tubular Ectasia of Rete Testis 694 696 Testicular Torsion/Infarction 700 Undescended Testis 704 Epididymitis/Orchitis 706 Scrotal Trauma 710 Hydrocele 714 Spermatocele/Epididymal Cyst 716 Adenomatoid Tumor 718 Varicocele 720

Approach to Scrotal Sonography 680 Diagnoses: Scrotum Introduction High-frequency transducer sonography, using grayscale along with pulsed and color Doppler, is the imaging modality of choice for evaluating patients who present with scrotal pathology. Scrotal ultrasound (US) is often requested in an emergency setting in cases of acute scrotal pain. The leading differential diagnoses in such a scenario include testicular torsion, acute epididymoorchitis, and traumatic injury (in the setting of preceding trauma). In the nonacute setting, scrotal ultrasound is often requested for evaluation of chronic testicular pain or a palpable scrotal mass. The differential diagnoses of a palpable mass includes testicular neoplasm, benign or malignant, and extratesticular masses including paratesticular lesions and inguinal hernia. Clinical correlation with history and symptoms is an extremely important aspect of scrotal sonography. Ultrasound Technique for Scrotal Evaluation Scrotal US is performed with the patient in the supine position and the scrotum supported by a towel placed between the thighs. Optimal results are obtained with a 9-15 MHz highfrequency linear-array transducer. Scanning is performed with the transducer in direct contact with the skin with copious amounts of gel; if necessary, a stand-off pad can be used for evaluation of superficial lesions. A curvilinear lower frequency transducer may be used for supplementary evaluation when the scrotum is too large to be evaluated with a linear high resolution transducer. The testes are examined in at least two planes, i.e., the longitudinal and transverse axes. The size and echogenicity of each testis and epididymis are compared with those on the opposite side. Scrotal skin thickness is evaluated for symmetricity as well as focal or diffuse edema. Color Doppler and pulsed Doppler parameters are optimized to display lowflow velocities and demonstrate blood flow in the testes and surrounding scrotal structures. Color Doppler ultrasound should include comparison of bilateral testicular spectral Doppler tracings. Power Doppler US may also be used to demonstrate intratesticular blood flow in patients with an acute scrotum, particularly in evaluation for torsion or infarct. When evaluating patients who present with an acute scrotum, the asymptomatic side should be scanned first in order to set the grayscale and color Doppler gain settings to allow comparison with the affected side, remembering that testicular torsion can be a bilateral process in 2% of patients. Transverse images with portions of each testis on the same image should be acquired in grayscale and color Doppler modes. Additional techniques, such as use of the Valsalva maneuver or upright positioning, can be used as needed for venous evaluation. Power Doppler sonography uses the amplitude of the Doppler signal independent of flow directionality. Therefore, power Doppler sonography has greater sensitivity than standard color Doppler for detecting low-flow states and provides essential information in diagnosis of complete testicular torsion. Clinical Perspective Acute Scrotal Pain In an emergency setting, acute scrotal pain should prompt one to assess the scrotum for epididymoorchitis, testicular torsion, and traumatic injury. History and physical examination are critical in making the correct diagnosis along with the sonographic appearance of the scrotum. Although acute epididymoorchitis and acute testicular torsion present similarly with acute onset of unilateral testicular pain, epididymoorchitis may be accompanied with fever &/or a Prehn sign (relief of pain with elevation of scrotum above the level of pubic symphysis). Moreover, the sonographic appearances for both diagnoses are very distinct: Edema with increased vascularity in epididymoorchitis, and edema with absent or reduced flow in torsion. A potential pitfall for testicular torsion is torsion-detorsion syndrome wherein the testis may detorse spontaneously, resulting in reactive hyperemia, which can appear sonographically similar to epididymoorchitis. An appropriate history preceding the clinical presentation may lead to the correct diagnosis. Torsion-detorsion syndrome will typically present with intermittent symptoms of pain and discomfort. epididymoorchitis will present with constant or worsening pain. Associated findings of inflammation in the ipsilateral scrotum, such as scrotal skin thickening and pyocele, also favors epididymoorchitis. Diagnosis of a traumatic scrotal injury is usually not difficult with a prior history of trauma (blunt or penetrating). The purpose of performing an ultrasound after trauma is to determine whether surgical exploration is required. Most cases with testicular rupture (tunica albuginea disruption) will need to be surgically repaired. In addition, large hematoceles or large hematomas resulting in nonviable testis may require surgical evacuation &/or debridement. Presence of color Doppler flow in the testis helps determine viability. It is extremely important to follow all such cases to resolution, as some hematomas may become infected and form an abscess. Chronic/Nonacute Scrotal Pathology In a nonacute setting, patients often present with an enlarged scrotum, palpable mass, or mild scrotal pain. An enlarged scrotum may be related to a hydrocele, spermatocele, scrotal wall edema, or inguinal hernia. In the setting of a palpable mass, ultrasound is extremely sensitive in detecting the presence of an intratesticular neoplasm, which is a malignancy until proven otherwise. Mild scrotal pain is often related to a varicocele, which can easily be diagnosed with color Doppler and Valsalva maneuvers. Summary The ability of ultrasound to diagnose the pathogenesis of the acute scrotum is unsurpassed by any other imaging modality. Ultrasound is the first-line imaging study performed in patients with acute scrotum. Knowledge of the normal and pathologic sonographic appearance of the scrotum and an understanding of the proper technique are essential for accurate diagnosis of an acute scrotum. High-frequency transducer sonography combined with color and power Doppler sonography provides information essential to reach a specific diagnosis in patients with testicular torsion, epididymoorchitis, and scrotal trauma. Selected References 1. Appelbaum L et al: Scrotal ultrasound in adults. Semin Ultrasound CT MR. 34(3):257-73, 2013 2. American Institute of Ultrasound in Medicine et al: AIUM practice guideline for the performance of scrotal ultrasound examinations. J Ultrasound Med. 30(1):151-5, 2011 3. Bhatt S et al: Role of US in testicular and scrotal trauma. Radiographics. 28(6):1617-29, 2008 4. Dogra V et al: Acute painful scrotum. Radiol Clin North Am. 42 (2): 349-63, 2004 5. Dogra VS et al: Sonography of the scrotum. Radiology. 227(1):18-36, 2003

PART II<br />

SECTION 10<br />

Scrotum<br />

Introduction <strong>and</strong> Overview<br />

Approach to Scrotal Sonography 680<br />

<br />

Testicular Germ Cell Tumors 682<br />

Gonadal Stromal Tumors, Testis 686<br />

Testicular Lymphoma/Leukemia 690<br />

Epidermoid Cyst 692<br />

Tubular Ectasia of Rete Testis 694<br />

696<br />

Testicular Torsion/Infarction 700<br />

Undescended Testis 704<br />

Epididymitis/Orchitis 706<br />

Scrotal Trauma 710<br />

Hydrocele 714<br />

Spermatocele/Epididymal Cyst 716<br />

Adenomatoid Tumor 718<br />

Varicocele 720

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