Azoospermia refers to complete absence of sperm in the semen. It accounts for 5-10% of male infertility 1.

It can be obstructive or non-obstructive, e.g. primary testicular failure. This differentiation is of utmost importance, as obstructive azoospermia can be corrected by surgical intervention 1-2.

Sonographic features that may be present with azoospermia include:

  • ectasia of rete testes: anechoic tubular structures in mediastinum testes.
  • tubular ectasia of epididymis: multiple anechoic tubular structures in epididymis head (the differential for this feauture includes spermatocele, epididymal cyst)
  • inflammatory epididymal mass: enlarged heterogenous epididymis head.
  • testicular volume: small sized testes (<7 cc) is seen in primary testicular failure. However, testicular volume is usually larger (>13 cc) in obstructive azoospermia2

Sonographic features that may present on transrectal ultrasound include:

  • absence of ductus deferens
  • dilated ductus deferens (diameter >1.5 mm) 
  • hypoplastic seminal vesicles (transverse diameter <7 mm and length <16 mm) 2-3
  • dilated seminal vesicles (transverse diameter >15 mm and length >25 mm) 2-3
  • inflammatory cyst(s) in ejaculatory duct

Similar features like absence or ductus deferens or seminal vesicle can be seen on MRI. Epididymal and seminal vesicle cysts can also be well seen. Endorectal MRI is the preferred modality.

Vasography (vasculodeferentography) has rare application now, however, theoretically stays the gold standard to evaluate obstructive azoospermia.

Patients with primary testicular failure (non-obstructive azoospermia) benefit from intracytoplasmic sperm injection. Obstructive azoospermia patients benefit from surgical correction such as vasoepididymostomy. Also, we can obtain sperm directly from epididymis or seminal vesicle, in cases of obstructive azoospermia.

Article information

rID: 16222
System: Urogenital
Tag: cases, cases
Synonyms or Alternate Spellings:
  • Azoospermia : radiological evaluation
  • Azoospermia : radiological assessment

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Cases and figures

  •  Case 1: ejaculatory duct obstruction
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