Obstructive Azoospermia

Obstructive azoospermia is the absence of sperm in the ejaculate despite normal sperm production, because the epididymis, vas deferens or ejaculatory ducts are blocked.

Azoospermia is confirmed when no sperm are found in the centrifuged pellet of at least two semen samples.

Azoospermia affects about 1% of men and 10 to 15% of infertile men. Obstruction accounts for about 40% of these. It is the most treatable form of azoospermia, because spermatogenesis is intact.

Pathophysiology. Causes by site:

• Epididymis: infection (chlamydia, gonorrhoea, tuberculosis), Young syndrome, scrotal surgery and idiopathic obstruction.
• Vas deferens: vasectomy, inguinal hernia repair (especially with mesh in infancy or adulthood), congenital bilateral absence of the vas deferens, and injury at pelvic or scrotal surgery.
• Ejaculatory ducts: Müllerian or Wolffian duct cysts, calculi, post-inflammatory fibrosis and instrumentation.

Sperm production continues, and the testes may show back pressure changes with time.

Primary infertility, or infertility after vasectomy. Normal virilisation, normal libido and erections, and normal testicular size (volume over 15 mL, length over 4 cm). The epididymis may be full and turgid. The vas may be absent or thickened and nodular. Low ejaculate volume suggests ejaculatory duct or seminal vesicle disease.

Past history of epididymitis, sexually transmitted infection, tuberculosis, hernia repair or scrotal surgery, and respiratory or sinus disease (cystic fibrosis spectrum).

• Semen analysis on two samples, with centrifugation and pellet examination. Volume, pH and seminal fructose: volume under 1.4 mL, acidic pH (under 7.2) and absent fructose indicate ejaculatory duct obstruction or absent vasa and seminal vesicles.
• FSH, LH, total testosterone: normal values support obstruction. FSH over 7.6 IU/L raises the possibility of coexisting testicular failure.
• Scrotal ultrasound: epididymal head dilatation, absent vas segments, varicocele and testicular lesions.
• Transrectal ultrasound: seminal vesicle anteroposterior diameter over 1.5 cm, ejaculatory duct diameter over 2.3 mm, midline cysts or calculi.
• CFTR gene analysis when the vasa are absent or the seminal vesicles are hypoplastic, with testing of the partner before assisted conception. Renal ultrasound when the vas is absent.
• Karyotype and Y chromosome microdeletion testing when testicular volume is reduced or histology is uncertain.
• Diagnostic testicular biopsy shows normal spermatogenesis, and is usually combined with sperm retrieval.

Differential diagnosis.

• Nonobstructive azoospermia
• Hypogonadotropic hypogonadism
• Retrograde ejaculation and anejaculation
• Congenital bilateral absence of the vas deferens
• Incomplete semen collection
• Ejaculatory duct obstruction

• Treat infection first: chlamydia with doxycycline 100 mg orally twice daily for 7 days, and culture directed antibiotics for other organisms. Treat partners.
• Reconstruction when the site is amenable:
  • Vasovasostomy for vasectomy reversal, done microsurgically. Patency is about 90% at under 3 years since vasectomy and falls to about 50% after 15 years or more. Pregnancy rates fall in parallel, from about 75% to 30%.
  • Vasoepididymostomy for epididymal obstruction or failed vasovasostomy, with patency of about 60 to 80% and pregnancy of about 20 to 40%.
  • Transurethral resection of the ejaculatory ducts for distal obstruction, or cyst unroofing.
• Sperm retrieval with intracytoplasmic sperm injection when reconstruction is not possible, not wanted, or has failed:
  • Percutaneous or microsurgical epididymal sperm aspiration, testicular sperm aspiration or testicular sperm extraction. Sperm are found in nearly all men with obstruction.
  • Cryopreserve spare sperm for later cycles.
• Perioperative cefazolin 2 g intravenously (3 g if over 120 kg) as a single dose. Analgesia: paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours for 3 to 5 days.
• Genetic counselling and partner CFTR testing when congenital absence of the vas is present or suspected.
• Assess the female partner at the same time, since age and ovarian reserve strongly affect the results of either route.

Monitoring. Semen analysis every 3 months for 12 months after reconstruction. Failure to achieve sperm by 6 months leads to sperm retrieval. Review of testicular size and testosterone after surgery in men with prior testicular damage.

Referral and escalation. Refer to a urologist with microsurgical experience and a fertility unit. Urgent referral for scrotal pain with fever or an acute scrotum after a procedure.