Azoospermia refers to complete absence of sperm in the semen. It accounts for 5-10% of male infertility 1.
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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.
- congenital bilateral absence of vas deferens (CBAVD)
- obstruction of vas deferens
- tubular ectasia of rete testes or epididymis
- inflammatory lesion of epididymis or vas deferens.
- inflammatory obstruction of ejaculatory duct
- iatrogenic injury (vasectomy, hernia repair etc)
- varicocoele (controversial, if it causes azoospermia)
Non-obstructive azoospermia (primary testicular failure)
- Klinefelter syndrome
- Y microdeletion
- unexpained testicular failure
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 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
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.
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.
- 1. Moon MH, Kim SH, Cho JY et-al. Scrotal US for evaluation of infertile men with azoospermia. Radiology. 2006;239 (1): 168-73. doi:10.1148/radiol.2391050272 - Pubmed citation
- 2. Du J, Li FH, Guo YF et-al. Differential diagnosis of azoospermia and etiologic classification of obstructive azoospermia: role of scrotal and transrectal US. Radiology. 2010;256 (2): 493-503. doi:10.1148/radiol.10091578 - Pubmed citation
- 3. Donkol RH. Imaging in male-factor obstructive infertility. World J Radiol. 2010;2 (5): 172-9. doi:10.4329/wjr.v2.i5.172 - Free text at pubmed - Pubmed citation