Azoospermia – What is it?

Azoospermia, defined as complete absence of sperm from the ejaculate, is present in less than 1% of all men and in 10-15% of infertile men. There are many causes of azoospermia

  1. Failure of hormones to adequately stimulate the testicles to produce sperm (also known as Pre-testicular)
  2. Primary testicular failure in which the sperm producing cells in the testicles are either missing or damaged
  3. Obstruction of the sperm delivery system (also known as Post-testicular)

This article will focus on obstructions in the sperm delivery system.

Obstruction as a cause for azoospermia

Obstruction is responsible for approximately 40% of cases of azoospermia. Obstructive azoospermia may result from blockage in any of the tubes leading from the testicle to the opening in the tip of the penis. These tubes are

  1. Epididymis
  2. Vas Deferens
  3. Ejaculatory duct

Causes of sperm obstruction

Vasectomy is the most common cause of obstruction in the vas deferens. Severe genital or urinary infections, injury during scrotal or inguinal surgery and birth defects are other common causes of obstructive azoospermia.

Treatments for sperm obstruction

Men with obstructive azoospermia may father children by

  1. Surgical correction of the obstruction,
  2. Retrieval of sperm from the male reproductive system for in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI).

Surgical treatment

Microsurgical vasectomy reversal

In the United States, estimates are that 500,000 to 750,000 vasectomies are performed annually; as many as 4%to 10% of these men later request reversal. A very important factor influencing the likelihood of sperm returning to the semen and of pregnancy after vasectomy reversal is the number of years between vasectomy and attempted reconstruction. Other factors influencing the success of vasectomy reversal include the:

  1. presence or absence of sperm seen during the surgery
  2. appearance of the vas fluid as seen during the surgery
  3. quality of the sperm in the vas fluid
  4. length of the vas segment between the epididymis and the vasectomy site
  5. presence or absence of a sperm granuloma (a lump of hardened, old sperm sometimes seen after vasectomy)
  6. age of the female partner.
 Vasal fluid Patency ratePregnancy rate
 Motile sperm 94%63%
 Nonmotile sperm 90%54%
 Sperm heads only 75%44%
 No sperm 60% 31%

There are two microsurgical procedures used for vasectomy reversal:  vasovasostomy  and vasoepididymostomy. Vasectomy reversal is usually performed with the patient under general anesthesia. Alternatively, the procedure can be performed with a local anesthetic (with or without sedation) or with a spinal or epidural anesthetic.


This method of microsurgery removes an obstruction and connects one part of the vas deferens to another part.  In addition to vasectomy reversal , this type of microsurgery is also  performed for blockage caused by injury during a hernia repair.

In a report by the Vasovasostomy Study Group, overall patency rate and pregnancy rate for more than 1200 vasovasostomy procedures were 86% and 52%, respectively. The patency rate and pregnancy rate fell from 97% and 76% at less than 3 years after vasectomy to 71% and 30% at 15 years or longer after vasectomy.

 Obstructive interval Patency ratePregnancy rate
 < 3 years 97%76%
 3-8 years 88%53%
 9-14 years 79%44%
 >15 years 71% 30%


This method of microsurgery removes an obstruction and connects the vas deferens to the epididymis. Vasoepididymostomy is considered one of the most challenging microsurgical procedures, requiring significant microsurgical experience. In addition to vasectomy reversal, it can also be performed for the following types of obstructions:

  1. congenital (present at birth)
  2. scarring from infections
  3. Unexplained blockage of the epididymis

Following this type of microsurgery, the patency rate and pregnancy rate range, respectively, from 67% to 85% and from 27% to 49%.

Repeat vasectomy reversals

A history of a previous vasectomy reversal attempt does not preclude a new attempt. Patency and pregnancy rates of 79% and 31%, respectively, have been reported for repeated reversals.

Transurethral resection of the ejaculatory ducts (TURED)

This method is used to treat blockage in the ejaculatory duct. This condition is uncommon. Ejaculatory duct obstructions (EDO)can be congenital, (due to abnormal development as a fetus) or acquired. Acquired obstructions may be secondary to trauma or infection/inflammation. Obstructed ejaculatory ducts are usually diagnosed by transrectal ultrasound imaging or by special radiographic tests called vasograms.

Transurethral resection of the ejaculatory duct results in the appearance of sperm in the ejaculate in 50-75% of cases. The pregnancy rate achieved by this surgery is about 25%.

Sperm retrieval techniques and IVF/ICSI

ICSI or intracytoplasmic sperm injection is a method to fertilize eggs during IVF in which a single sperm is injected into a single mature egg. ICSI must be used in all cases in which sperm are retrieved from the testes or epididymis. This is necessary for two reasons:

  1. The amount of sperm obtained is usually very small
  2. Sperm from the testicles and most of the epididymis have not developed the capability to fertilize an egg without help

ICSI provides fertilization rates of 45-75% per injected oocyte when surgically retrieved epididymal or testicular spermatozoa are used.

Sperm retrieval for ICSI

There are different methods employed for retrieving sperm for ICSI

  1. MESA – Microsurgical Epididymal Sperm Aspiration
  2. PESA – Percutaneous Epididymal Sperm Aspiration
  3. TESE – TEsticular Sperm Extraction
  4. TESA -Percutaneous TEsticular Sperm Aspiration
  5. VASA – VAsal Sperm Aspiration
  6. SESA – SEminal vesicle Sperm Aspiration

Microsurgical methods utilize an incision and surgery tiny instruments with the assistance of large, high powered surgical microscopes.

Percutaneous methods do not make an incision but rather, use a tiny needle directed in the appropriate place to aspirate sperm. This is sometimes aided by transrectal ultrasound. The choice of sperm retrieval method in men with obstructive azoospermia depends primarily on the experience and preference of both the urologist.

There are not enough data to conclude that either the technique of sperm retrieval (microsurgical or percutaneous) or the source of sperm (testicular, epididymal, vasal or seminal vesicular) significantly affects pregnancy rates. Each technique and sperm source usually provides a sufficient number of sperm for ICSI and may provide enough viable sperm for cryopreservation (freezing).

Sperm retrieval may be performed prior to or simultaneously with the female’s egg retrieval. Sperm retrieval is most commonly performed before the female starts fertility medication injections for IVF.

Microsurgical reconstruction versus sperm retrieval with IVF/ICSI

In good prognosis cases, microsurgical reconstruction may be more cost-effective than sperm retrieval with IVF/ICSI, and allows couples to have subsequent children without additional medical treatment.

Many couples will opt for IVF/ICSI however. In couples with good prognosis, a higher percentage of couples will achieve pregnancy more quickly with IVF/ICSI. Also, the presence of female infertility factors may reduce the chance for pregnancy after microsurgical reconstruction.