Testicular Ultrasound

Aka: Testicular Ultrasound, Scrotal Ultrasound, Ultrasound Testes, Echography of Scrotum, Ultrasound of Scrotum

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II. Indications

  1. Scrotal or testicular Trauma
    1. Testicular Torsion
    2. Torsion of Testicular Appendage
    3. Testicular rupture
  2. Infection
    1. Orchitis
    2. Epididymitis
  3. Palpable mass evaluation (or Scrotal Swelling)
    1. Hydrocele
    2. Varicocele
    3. Malignancy
    4. Inguinal Hernia

III. Anatomy: Landmarks

  1. Scrotal wall
    1. Wall thickness normally 2-7 mm
  2. Testicle
    1. See Testicle Size
    2. Appears mid-level echogenicity with fine grain, smooth homogeneous appearance (similar to liver on Ultrasound)
    3. Surrounded by tunica vaginalis (2 layers) and tunica albuginea
      1. Tunica vaginalis parietal layer
      2. Small amount of fluid present normally (1-2 ml)
      3. Tunica vaginalis visceral layer
      4. Tunica albuginea
    4. Mediastinum Testis
      1. Hyperechoic linear band bisects the Testicle
      2. Formed by the tunica albuginea where it invaginates into Testicle from the posterior aspect
    5. Rete Testis
      1. Coalescence of the seminiferous tubules at the posterior medial aspect of the Testicles
  3. Epididymis
    1. Medial elongated structure appears similar to a worm lying on the surface of the Testicle
    2. More echogenic and coarse, less homogeneous appearance than Testicle
    3. Epididymal cysts are not uncommon (especially following Vasectomy)
    4. Minimal to no color flow doppler in the normal epididymis
    5. Normal diameter varies from 10-12 mm at the epididymal head to 2-5 mm at the epididymal tail

IV. Imaging

  1. Patient position
    1. Position patient in frog-leg position
    2. Place rolled towels between thighs (raises Scrotum)
    3. Penis is reflected upward toward one side of Abdomen with overlying towel and patient's hand over the top
  2. Transducer
    1. Linear Array Probe (7.5-12 MHz) - Vascular Access transducer
    2. Transducer indicator is to patient's right (9:00) in transverse (short axis)
    3. Transducer indicator is to patient's head (12:00) in longitudinal (long axis)
  3. Precautions
    1. Keep patient warm
      1. Cold environment significantly reduces scrotal Blood Flow
      2. Use warmed towels and blankets
      3. Warm Ultrasound gel
        1. Warm against patients core skin (or bottle can be microwaved for 20-30 seconds)
        2. Test bottle for excessive heat to prevent burns
    2. Testicular Torsion pitfalls
      1. Blood Flow around the outer aspect of the Testicle does not exclude Testicular Torsion (different vessels)
      2. Testicular Torsion evaluation requires identifying flow in both testicular arteries and veins
  4. Views: Overall survey
    1. Start with probe over midline Scrotum in transverse position
      1. Obtain quick overview of positioning
    2. Scan each Testicle (starting with the normal, unaffected side)
      1. Transverse (short-axis) plane
        1. Slide and tilt to obtain transverse cuts through Testicle from superior to inferior
      2. Longitudinal (long-axis) plane
        1. Start midline of Testicle at superior aspect
        2. Scan Testicle by gradually tilting probe from medial to lateral
        3. Slide the probe inferiorly from superior to mid-Testicle and re-scan, tilting from medial to lateral
        4. Slide the probe inferiorly from mid-Testicle to lower Testicle and re-scan, tilting from medial to lateral
    3. Testicular flow evaluation (color flow doppler)
      1. Coronal view
        1. Rest hand and transducer against the ipsilateral thigh
        2. Transducer indicator at 12:00
        3. Energy directed at Testicle from the side
        4. Apical view may be used as an alternative when comparing flow in both Testicles simultaneously
          1. Hand rests on thigh, transducer transverse with indicator at 9:00 and energy directed up towards head
      2. Turn on color flow doppler
        1. Start on contralateral (good, normal, painless) side
          1. Adjust color doppler settings (drop down doppler gain to improve sensitivity for torsion)
        2. Identify at least one set of intra-testicular vessels (one will be blue and the other red)
        3. Turn on pulse wave doppler and move calipers to each vessel in turn
          1. Demonstrate that one vessel has pulsatile characteristics (artery)
          2. Demonstrate that one vessel has more continuous characteristics (vein)
          3. This technique can be simulated and practiced on the Thyroid Gland
        4. Demonstrating both venous and arterial flow excludes complete Testicular Torsion
          1. Partial torsion may still be present (<450 degree twist)
        5. Decreased flow should be confirmed in multiple views (e.g. coronal and apical views)

V. Findings: Painful scrotal enlargement

  1. Epididymitis
    1. Increased color flow doppler compared to normal appearance (typically minimal flow)
    2. Epididymal swelling (see normal sizes above under landmarks)
    3. Darker, less echogenic appearance due to increased water content (typically slightly more echogenic than Testicle)
    4. Epididymal head (superior, medial aspect of Testicle) is first region of epididymis affected
  2. Orchitis
    1. Darker, less echogenic appearance due to increased water content (similar to Epididymitis appearance)
  3. Testicular Torsion
    1. Decreased or absent testicular arterial and venous Blood Flow as compared with the opposite side
    2. Affected Testicle may be enlarged
    3. Necrotic testicular regions may appear with a mix of hypoechoic and heterogeneous areas
    4. Reactive Hydrocele may be present
  4. Torsion of the appendix Testicle
    1. Mimics Testicular Torsion
    2. Diminished flow and swelling of the affected testicular appendage
  5. Testicular rupture

VI. Findings: Painless scrotal enlargement or mass

  1. Hydrocele (most common cause of painless swelling)
    1. Reactive Hydrocele often accompanies other testicular or scrotal conditions
    2. Hypoechoic (black) region surrounding the Testicle of >2 mm
      1. Although tunica vaginalis normally has a small amount of fluid within, Hydroceles have >2 mm surrounding the tesicle
    3. Septations of the Hydrocele may suggest more complex cause (e.g. infection, malignancy)
  2. Spermatocele
    1. Most commonly caused by trapped sperm following Vasectomy
    2. Appears as anechoic cyst with septations, most commonly within the epididymal head
  3. Varicocele
    1. Most are left sided (99%)
      1. Consider pelvic or abdominal venous obstruction if right sided Varicocele
    2. Cluster of thinly walled anechoic tubules >2mm in diameter
    3. Increased flow on color flow doppler ot power doppler
  4. Indirect Inguinal Hernia
    1. Anechoic (dark) appearance with peristalsis and shadowing
  5. Testicular Cancer
    1. Solid or heterogeneous hypoechoic lesions within Testicle
    2. Testicular microlithiasis may be a precursor to Testicular Cancer (but common, seen in 6% of men)
      1. Small hyperechoic numerous dots within the Testicle

VII. References

  1. Jorgensen (2012) Introduction and Advanced Emergency Medicine Ultrasound Conference, GulfCoast Ultrasound, St. Pete's Beach

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