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Azoospermia

Azoospermia refers to complete absence of sperm in the semen. It accounts for 5-10% of male infertility1.

Pathology

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 intervention1-2.

Aetiology
Obstructive azoospermia
non-obstructive azoospermia (primary testicular failure)

Radiographic assessment 

Scrotal ultrasound

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.
Transrectal ultrasound

Sonographic features that may present on transrectal ultrasound include

  • absence of vas deferens
  • dilated vas 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
MRI

Similar features like absence or vas 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)

This has rare application now, however, theoretically stays the gold standard to evaluate obstructive azoospermia.

Treatment and prognosis

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.

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