A testicular ultrasound is a non-invasive medical imaging procedure that uses high-frequency sound waves to create detailed, real-time images of the scrotum and its contents. This technique is the primary tool doctors use to visualize the testicles, epididymis, and surrounding structures. The test helps differentiate between various causes of scrotal pain, swelling, or a palpable lump, providing detailed information about the size, shape, and texture of tissues. It is a quick, painless procedure that serves as an initial diagnostic step without radiation exposure.
Evaluating Lumps and Masses
The primary concern when a lump is felt in the scrotum is often the possibility of cancer, and the ultrasound is highly effective at characterizing these masses. The test helps distinguish between solid masses, which are more likely to be tumors, and cystic masses, which are typically benign and fluid-filled. By analyzing the echoes of the sound waves, the radiologist can determine the internal composition of a mass.
Solid masses within the testicle are viewed with suspicion because the majority of intratesticular tumors are malignant. Testicular cancer often appears on the ultrasound as a solid, well-defined mass that is “hypoechoic,” meaning it appears darker than the surrounding normal testicular tissue. While a tumor is often highly vascular, or hypervascular, the absence of increased blood flow does not rule out a testicular cancer diagnosis.
The ultrasound is useful for identifying the specific characteristics of different types of tumors. Seminomatous germ cell tumors (SGCTs) tend to be uniform and homogeneous. Non-seminomatous germ cell tumors (NSGCTs) are more likely to show complex features, including solid and cystic areas, hemorrhage, or calcification. These findings, combined with blood tests for tumor markers, guide the decision on whether a mass requires surgical removal for definitive diagnosis.
In contrast to solid tumors, cystic masses, such as simple intratesticular cysts, are typically benign. These cysts appear as well-defined, fluid-filled structures that lack internal vascularity on Doppler imaging. Epidermoid cysts, another benign mass, sometimes present with a characteristic “onion skin” appearance due to concentric layers of keratin debris. Identifying these clear, benign features on the ultrasound can prevent unnecessary surgery.
Assessing Blood Flow and Vascular Conditions
Doppler ultrasound is integrated into the procedure, allowing the sonographer to visualize and measure blood flow within the testicular and surrounding vessels. This capability is necessary for diagnosing conditions where blood supply is compromised or abnormal. The Doppler component uses color mapping to show the direction and speed of blood movement, which is displayed over the traditional grayscale image.
Testicular torsion is the most time-sensitive condition evaluated by Doppler ultrasound, as this emergency involves the spermatic cord twisting and cutting off blood supply. In cases of complete torsion, the ultrasound shows absent or severely reduced blood flow within the affected testicle, appearing distinctively dark compared to the unaffected side. Prompt identification of this absent flow is crucial because delayed diagnosis can lead to the loss of the testicle.
The Doppler ultrasound also diagnoses varicocele, an enlargement of the veins (pampiniform plexus) within the scrotum. These dilated veins appear as a cluster of anechoic, tubular structures adjacent to the testicle. The Valsalva maneuver, where the patient strains, is used during the scan to confirm the diagnosis. The maneuver increases abdominal pressure, causing blood to reflux, or flow backward, into the enlarged veins. This flow reversal is clearly visible on the Doppler image. A varicocele is generally diagnosed when the diameter of one or more veins measures greater than 3 millimeters, especially with venous reflux lasting longer than two seconds during the maneuver.
Identifying Inflammation and Fluid Accumulation
The testicular ultrasound is highly effective at identifying inflammatory conditions and various forms of fluid accumulation. These conditions are common causes of pain and swelling and require visual confirmation for proper treatment. The detailed images help differentiate generalized swelling from localized structural problems.
A common finding is a hydrocele, a collection of serous fluid that accumulates between the layers surrounding the testicle. On the ultrasound, a hydrocele appears as an anechoic, or dark, fluid collection surrounding the testicle, often pushing it to one side of the scrotal sac.
Inflammatory conditions, such as epididymitis (inflammation of the coiled tube) and orchitis (inflammation of the testicle), have clear signatures on the ultrasound. These infections typically cause the affected structures to appear enlarged and darker (hypoechoic) due to edema. Crucially, in contrast to torsion, the color Doppler component shows a marked increase in blood flow, known as hyperemia, in the inflamed area.
Associated findings often include a reactive hydrocele or thickening of the scrotal wall due to the inflammatory response. The ultrasound can also assess for complications following trauma, such as a hematoma, which appears as a collection of clotted blood with mixed echogenicity. Distinguishing the hypervascularity of infection from the absent flow of torsion is a diagnostic strength when evaluating acute scrotal pain.