Men who can achieve ejaculation but there are few, if any, sperm cells in the ejaculated fluid are usually diagnosed with non-obstructive azoospermia (NOA). Until recently, it was thought that the only way these men could have children was through sperm donation or adoption. A new treatment for male infertility, however, is bringing hope to many men who suffer low-sperm-count male infertility.

The new treatment — microdissection testicular sperm extraction (micro-TESE) — evolved from testicular biopsy techniques that involve removing a small sample of tissue from a testicle. Microscopic examination of this tissue sometimes reveals sperm cells in the extracted tissue of men who were considered sterile due to testicular failure (low sperm count).

Intracytoplasmic Sperm Injection (ICSI)

Researchers at the Weill Cornell Medical College in New York City developed a method for extracting these sperm cells from biopsied testicular tissue. Once healthy sperm cells are harvested using the micro-TESE method, they can be used to fertilize an egg to produce a pregnancy.

To achieve fertilization, a single extracted sperm cell is then injected into a female egg in a form of in vitro fertilization (IVF) called intracytoplasmic sperm injection (ICSI). The sperm cell can be extracted in conjunction with a woman’s menstrual cycle to take full advantage of her natural ovulation process or can be extracted earlier and kept frozen until the optimum moment.

Refinement of Technique Brings Higher Rate of Success

Early attempts at fertilization following TESE produced pregnancy rates of only about 20%. Damage to the sperm during extraction and fertilization are thought to be one reason for the low rate of success.

With further research, the Cornell research team developed ways to refine their technique to produce less damage to the sperm cells and surrounding testicular tissue. One such refinement is the use of greater magnification of the microscopes used during the extraction and injection procedures. Greater magnification allows doctors to identify and isolate individual sperm cells and extract them successfully with minimal damage to the sperm cells and to the testicular tissue surrounding the extraction site. By using these tissue-sparing micro-TESE techniques, it’s possible to use the initial incision to extract more tissue for sperm extraction later if the initial attempt fails.

Advances in both TESE and ICSI procedures improved the fertilization rate at Cornell. In the absence of any other genetic defects that hinder reproduction, the Cornell team has achieved a 55% success rate for clinical pregnancy for TESE patients. A clinical pregnancy is defined by the ability to see the fetal heartbeat using ultrasound scanning.

It was once believed that a sperm cell must travel through the entire male reproductive system to become healthy enough to fertilize an egg. Work using TESE on patients diagnosed with unreconstructable obstructive azoospermia proved this understanding to be incorrect. Vasectomy is one form of obstructive azoospermia that cannot always be reversed.

In one Cornell study of micro-TESE on men with NOA, six men had lost a testicle to cancer and five had previously undergone chemotherapy.


  1. "Non-obstructive Azoospermia and TESE." Weill Cornell Medical College James Buchanan Brady Foundation Department of Urology. Cornell University, n.d. Web. 9 Mar. 2015.
  2. "News and Research: Microsurgery for Fertility in "Sterile" Men." Henry Ford Health System. Henry Ford Health System, 16 Feb. 2015. Web. 9 Mar. 2015.