Densely packed seminiferous tubules separated by thin, fibrous septa

Seminiferous tubules join to form rete testis , which converge posteriorly into efferent ductules

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  Penetrate posterior tunica albuginea at mediastinum to form head of epididymis

  
  
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  May become dilated, but tubular appearance and location should differentiate from mass

Tunica albuginea forms thick, fibrous capsule around testis

Mediastinum testis is thickened area of tunica albuginea where ducts, nerves, and vessels enter and exit testis

Testicular descent : Testis develop in retroperitoneum and descend through inguinal canal to scrotum

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  Failure of descent results in cryptorchidism

Tunica vaginalis : Mesothelial-lined sac around anterior and lateral sides of testis formed during descent

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  Fluid ( hydrocele ) may accumulate between parietal and visceral layers (hydrocele)

Appendix testis : Embryologic remnant, which forms small, nodular protuberance from surface of testis

Crescent-shaped structure along posterior border of testis

Efferent ductules from testis form epididymal head , which coalesce to form a single, long, convoluted tubule in epididymal body

Tubule continues inferiorly to form epididymal tail, which is attached to lower pole of testis by loose areolar tissue

Tubule emerges at acute angle from tail as vas deferens, which continues cephalad within spermatic cord

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  Eventually merges with duct of seminal vesicle to form ejaculatory duct

Appendix epididymis : Small, nodular protuberance from surface of epididymis similar to appendix testis

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  Both appendages can undergo torsion and form scrotal calculi

Contains vas deferens, nerves, lymphatics, and vessels

Begins at internal (deep) inguinal ring and exits through external (superficial) inguinal ring into scrotum

Testicular artery is primary blood supply to testis

Pampiniform plexus is interconnected network of small veins, which can dilate resulting in varicocele

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  This plexus merges to form testicular veins

  
  
  
  
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    Right testicular vein drains to inferior vena cava

    
    
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    Left testicular vein drains to left renal vein

  
  

Lymphatic drainage follows testicular veins

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  Right side drains to interaortocaval chain

  
  
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  Left side drains to left paraaortic nodes near renal hilum

Layers of spermatic cord and scrotum form during testicular descent through abdominal wall

High-frequency (10- to 15-MHz) linear transducer

Patient in supine position with penis positioned on anterior abdominal wall and draped with towel

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  Folded towel placed between thighs to elevate scrotum

Use copious gel; may need stand-off pad for superficial lesions

Image in both longitudinal and transverse planes

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  Size and echogenicity of both testes and epididymitides should be symmetric

Always evaluate asymptomatic side 1st to adjust settings

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  Serves as standard to compare with symptomatic side

  
  
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  Color Doppler should be optimized for low-flow state

  
  
  
  
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    Power Doppler may be needed if flow is difficult to document; this is particularly true in children

  
  

Doppler particularly important in setting of acute pain

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  Obtain “buddy shot” (both testes on same image) for easy comparison of flow between sides

Additional imaging during Valsalva maneuver and upright positioning important when evaluating for varicocele or inguinal hernia

Testes : Ovoid, homogeneous, medium-level, granular echotexture

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  Mediastinum testis may appear as prominent echogenic line emanating from posterior testis

  
  
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  Blood flow

  
  
  
  
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    Testicular artery pierces tunica albuginea and arborizes over periphery of testis

    
    
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    Multiple radially arranged vessels travel along septa

    
    
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    May have prominent transmediastinal artery

    
    
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    Tunica vasculosa : Vascular plexus in periphery of testis, beneath tunica albuginea

    
    
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    Low-velocity, low-resistance waveform on Doppler imaging with continuous forward flow in diastole

  
  

Epididymis : Iso- to slightly hyperechoic compared with testis

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  Best seen in longitudinal plane

  
  
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  Head has rounded or triangular configuration

  
  
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  Head: 10-12 mm; body and tail often difficult to visualize

  
  
  
  
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    May be helpful to follow in transverse plane if difficult to visualize in longitudinal plane

  
  

Spermatic cord

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  Scan along course of inguinal canal; may be difficult to differentiate from surrounding soft tissues

  
  
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  Slow flow in pampiniform plexus may make identification on color Doppler difficult

  
  
  
  
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    Use provocative maneuvers (Valsalva, standing), especially when looking for varicocele

  
  

Is pain acute?

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  Torsion vs. epididymitis/orchitis

  
  
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  Color Doppler is key to diagnosis

Is there palpable mass?

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  Intratesticular masses are overwhelming malignant

  
  
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  Extratesticular masses typically benign

  
  
  
  
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    Cystic-appearing extratesticular masses include: Hydrocele, varicocele, spermatocele, epididymal cyst, tunica albuginea cyst

    
    
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    Solid extratesticular masses include: Scrotal calculi, inguinal hernia with bowel &/or omentum, or, more rarely, epididymal adenomatoid tumor or fibrous pseudotumor