Testicular Ultrasound (Scrotal Sonography)

Scrotal ultrasonography (synonyms: testicular sonography; testicular ultrasound) is a method of examining the scrotal organs testis and epididymis with ultrasound. It is considered the gold standard of imaging diagnostics of this body region. Scrotal ultrasonography is used to determine testicular volumes and to examine the testicular parenchyma (testicular tissue). Especially in the diagnosis of “acute scrotum“, testicular torsion, scrotal sonography allows a fast and meaningful diagnosis. Another example of diagnostics in the testicular area is the detection of a varicocele (varicose vein) by demonstrating venous reflux (backflow) in the course of duplex sonography. In this regard, scrotal sonography has a sensitivity (percentage of diseased patients in whom the disease is detected by the use of the test, i.e., a positive test result occurs) of almost 100% in the detection of pathological findings. There is also a high hit rate when assessing the type of pathology. An important application of testicular sonography is the screening of risk groups for malignant diseases of the testis. The patient clientele listed below should be considered a high-risk group:

  • Z. n. Maldescensus testis (location of the testis outside the scrotum) – 40-fold increased risk of degeneration.
  • Examination of the contralateral (mutual) testis in testicular tumor or Z. n. Ablatio testis (surgical removal of a testicle).
  • Positive family history
  • Control for known microlithiasis testis (ultrasound findings of the testis showing multiple, 1-3 mm hyperdense (dense) areas scattered evenly throughout the tissues of the testis; a meta-analysis showed a factor of 8.5 increased risk of testicular tumors for this condition)

Indications (areas of application)

Scrotal sonography is performed in or suspected of:

  • Abscesses (encapsulated accumulations of pus) in the testicular region.
  • Malformations of the testicles
  • Funiculocele – cyst (fluid-filled cavity; bean- to olive-sized) formed by accumulation of tissue fluid in the region of the spermatic cord (lat. Funiculus spermaticus).
  • Spermatocele – A retention cyst formed by an outflow obstruction and filled with protein-rich fluid containing sperm.
  • Gynecomastia (male breast growth) of unclear etiology.
  • Testicular volumetry (measurement of testicular volume) in growth disorders in adolescence.
  • Testicular torsion (acute scrotum) – Acute inferior blood flow to the testis caused by the sudden rotation of the testis around its vascular pedicle.
  • Hyatid (testicular or epididymal appendage) – Hyatid torsion is an important differential diagnosis to testicular torsion.
  • Hydrocele – Mostly unilateral accumulation of serous (“belonging to the blood serum”) fluid in the testicular sheaths.
  • Infertility (infertility).
  • Positional abnormalities of the testes (maldescensus testis/testicular undescent; cryptorchidism, i.e., nonpalpable (hidden) testis):
    • Abdominal testis (Retentio testis abdominalis).
    • Inguinal testis (Retensio testis inguinalis).
    • Gliding testis (Retensio testis prescrotalis; gliding testis).
    • Pendulum testis (Retractile testis) [norm variant].
  • Microlithiasis testis (see above).
  • Pathological tumor markers – e.g. AFP (alpha-fetoprotein) or beta-HCG.
  • Pain in the testicular area
  • Scrotal hernia – prolapse of parts of the intestine from the abdomen into the scrotum.
  • Trauma in the testicular area – e.g. hematocele (bruise of the testicles).
  • Tumors of the testis or epididymis
  • Varicocele (varicose vein)
  • Follow-up of epididymitis (epididymitis) and orchitis (testicular inflammation).
  • Z. n. Orchidopexy (surgical fixation of the testis in the scrotum).

Before the examination

Before the examination, a detailed medical history and a thorough physical examination is necessary. This includes careful palpation of the scrotal organs and groin region. As a rule, scrotal sonography follows a conspicuous palpation finding (palpation finding) as an obligatory diagnostic procedure. Diaphanoscopy (fluoroscopy of the scrotum for the diagnosis of varicoceles), which was often performed in the past, is no longer important for the clinical examination.

The process

Scrotal sonography is performed using high-frequency transducers (7-10 MHz), which provide a high resolution image, because of the very good accessibility of the testes. In addition, duplex sonography (combination of B-scan with PW Doppler/Pulse Wave Doppler; frequency >10 MHz) of the testicular vessels is performed, which allows assessment of the blood flow situation. The examination does not cause pain and is quick and easy to perform. Above all, the absence of radiation exposure and the non-invasive application are advantages of the examination. As a paired organ, both testes should always be examined in side-by-side comparison and the healthy side should be started with. Volumetry of the testes is an important component. The normal volume in adolescence is 18-28 ml. During the examination the patient is in supine position. Placing a towel (“testicular bulb”) underneath optimizes the examination conditions. The healthy testis has a homogeneous echo structure, which is dependent on age. Compared to the testis, the epididymis is more echo-rich and lies on the testis from the dorsolateral side (“towards the back and laterally”). In the case of orchitis (inflammation of the testis) or epididymitis (inflammation of the epididymis), the corresponding tissue may present as hyperechogenic (dense), for example. Simple cysts in the testicular region may represent an incidental finding; they are usually round, anechoic, and clearly demarcated from the surrounding tissue. A varicocele of the testis can be visualized at this site with color Doppler ultrasound. In the case of a varicocele, the vein diameter of the pampiniform plexus (plexus of veins of the testis and epididymis, which unites as part of the spermatic cord through the inguinal canal to the testicular vein) and especially the swelling of the diameter in the Valsalva test (pressure increase in the abdomen by pressing) is determined. The examination is also used, for example, to check the success of therapy after surgical treatment. Doppler sonography is based on the so-called Doppler effect: the ultrasound frequencies are reflected by passing erythrocytes (red blood cells). This frequency shift depends on the flow velocity and the flow direction of the erythrocytes. The color coding of Doppler sonography allows characterizing statements regarding the properties of the blood-supplying system. This examination technique also plays a significant role in testicular torsion. Testicular torsion is considered proven when there is evidence of lack of central perfusion (blood flow of central vessels). Furthermore, the testicular vessels (blood vessels of the testis) in the area of the funiculus spermaticus (bundle of vessels, nerves and the vas deferens) should be visualized. If these present as a spiral in the course, there is also a high probability of testicular torsion (sensitivity: 96%). Of particular importance is the diagnosis of space-occupying lesions in the testicular region, the following neoplasms (neoplasms) of the testis should be mentioned in this context:

  • Chorionic epithelioma (synonym: chorionic carcinoma) – infiltrative growing tumor from anaplastic trophoblastic cells.
  • Funicular sarcoma – Malignant tumor originating from the supporting tissue of the funiculus (bundle of vessels, nerves and the vas deferens) and metastasizing early into the blood vessels (hematogenous).
  • Leydig cell tumor – tumor that is rarely malignant (malignant); it is often endocrine active; increased testosterone production leads to pubertas praecox (puberty beginning too early) in childhood; in adulthood, estrogen production predominates and leads to gynecomastia (enlargement of the mammary gland in men) and loss of libido
  • Metastases (daughter tumors) – e.g. in melanoma (black skin cancer), penile carcinoma, prostate carcinoma.
  • Malignant lymphoma (“lymph node cancer“).
  • Seminoma (malignant germ cell tumor)
  • Teratoma (germ cell tumor; the mature form is benign; the immature form is malignant (malignant) and is called teratocarcinoma).

After the examination

After the examination, further therapeutic and diagnostic measures are initiated, if necessary, according to the findings obtained. In the case of “acute scrotum“, this is often the surgical exposure of the testicles to take care of a possible hydrocele or testicular torsion. Especially in the case of testicular torsion, surgery is the treatment of choice.If a mass is detected, tumor diagnosis with characterization of the primary tumor and staging (determination of the degree of spread of a malignant tumor) is performed. Further notes

  • Testicular lesions (testicular incidentalomas; space-occupying lesion): diameter of < 5 mm is “extremely unlikely” to be malignant..In one study, malignant tumor was identified in one-third of patients with testicular incidentalomas < 10 mm; no tumor was found in patients with lesion diameter < 5 mm.