Many of the men seen in my practice for male infertility are azoospermic. This means they have no measurable amount of sperm in their ejaculate. This is a significant issue for these men wanting to have a biological child. Approximately half of these men have Obstructive Azoospermia (OA). Their testes produce enough sperm, but a blockage exists in either the vas deferens or the epididymal tubules that prevent the transport of sperm from the testes to the tip of the penis. Sometimes the vas deferens and epididymal tubules are missing. The remaining half of our azoospermic patients have Non-Obstructive Azoospermia (NOA). Their vas deferens and tubules are clear and open, but the ability of their testes to produce sperm is impaired.
Medical interventions exist that enable many men with azoospermia to father their own biological children. Blockages can be surgically removed, and sperm production can sometimes be improved with pharmacological treatments. However, for most men with NOA and many with OA, the only avenue available for achieving a pregnancy with a partner is to have sperm surgically retrieved from the testes and then used in an assisted reproductive technology (ART) treatment protocol involving in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).
What is TESE?
In conventional testicular sperm extraction (TESE), a small incision is made in the scrotum exposing the testes. An incision is then made in one of the testes, through the tunica albuginea (protective outer covering of the testis) to expose its parenchymal (working) tissue. Special care is taken to avoid blood vessels. Pressure is applied along the incision until tissue containing seminiferous tubules protrudes through the incision site. This tissue is surgically removed and set aside for cryopreservation and/or immediate use in IVF/ICSI. The procedure is then repeated on the other testis.
Seminiferous tubules are the site of spermatogenesis (sperm production). However, spermatogenesis is not uniform throughout the testes, and so at any given time, some seminiferous tubules will have much higher concentrations of sperm than others. It is not possible to evaluate the degree of spermatogenesis in seminiferous tubules with the naked eye. So a surgeon has no way of visually assessing the tissue he intends to extract during a TESE for the presence of sperm. For men with OA this conundrum is usually not problematic. They produce plenty of sperm, so chances are quite good that testis tissue retrieved by conventional TESE will contain sufficient sperm for IVF/ICSI. This is not the case however for men with NOA. Because their ability to produce sperm is impaired, the sperm concentration in their seminiferous tubules can range from adequate in some tubules to non-existent in others. As a result, they run the very real risk of having testis tissue retrieved by conventional TESE that is devoid of sperm and therefore unsuitable for IVF/ICSI despite having sufficient sperm production in another portion of the testicle.
When sperm are not found in conventional TESEs, fertility specialists often counsel patients that no viable option exists to achieve a pregnancy with a partner. Patients are encouraged to start looking at sperm donors. This is outdated advice given by professionals who are unfamiliar with microdissection testicular sperm extraction (micro TESE).
What is microTESE?
A microTESE is a very different, far more complex type of surgical sperm retrieval compared to a conventional TESE. It is performed by an experienced urologic surgeon, who is an expert in the use of an operating microscope. The surgeon is assisted by a team of laboratory andrologists (specialists in the laboratory techniques required to identify and extract sperm from testicular tissue). An incision is made in the scrotum exposing the testes. Thirty or more microscopic specimens containing seminiferous tubules are taken from multiple sites on each testis. Individual seminiferous tubules in each of these samples are examined in the operating room by the laboratory andrologist to determine the presence of sperm. Seminiferous tubules containing sperm are usually plumper, light yellow in color, and often situated close to blood vessels. The surgeon is thus able to extract only tissue with the best potential to contain sperm, which is key to the success of the procedure (1). Once the tissue has been extracted, the laboratory andrologist will further examine it to assess sperm quality (concentration, maturation, morphology). The andrologist will also prepare the tissue for immediate use or cryopreservation. Using this approach, the operating team can focus on sites that appear to yield the best sperm concentration and quality, ensuring that a sufficient quantity of the most “promising” tissue is extracted. A microTESE typically takes several hours from the first incision to last suture. A conventional TESE is usually completed in under an hour.
MicroTESE offers several advantages over conventional TESE (2,3). Studies show that for men with NOA, sperm retrieval rates (SRR) by micro TESE are significantly higher than conventional TESE. “Sperm was recovered from those with hypospermatogenesis in 84% and 92.9% by conventional and microdissection TESE, respectively. In the case of maturation arrest, SRR was 27.3% and 36.4% respectively. In cases of Sertoli-cell-only syndrome (SCOS), the SRR was 6.2% and 26.9% respectively.”1 The use of an operating microscope minimizes the amount of tissue that is removed, as many microscopic specimens are taken rather than larger biopsies. The use of an operating microscope also enables the surgeon to avoid disrupting blood vessels, decreasing the likelihood of damaging vascularized areas of the testes. This minimizes trauma and the resulting loss of functionality, such as a decline in testosterone production. Better retrieval rates enable andrologists to cryopreserve testicular tissue for later use. Using cryopreserved sperm eliminates the need for synchronizing egg and sperm retrievals. It also eliminates the trauma and potential tissue damage caused by multiple sperm retrievals.
There has been some debate over the use of fresh versus thawed sperm for ICSI (4). Many fertility specialists believed better outcomes are achieved with fresh sperm, as cryopreservation damages both cell and acrosome membranes and increases the damage caused by sperm oxidative stress. However several recent studies refute this assumption. A recent review of data from 224 studies focusing on men with NOA revealed no difference in fertilization and pregnancy rates with fresh versus cryopreserved sperm used for ICSI.
The Bottom Line
Microdissection testicular sperm retrieval is offering new hope to men with NOA. However, I am ending this blog on a cautionary note. This is not a procedure that can be done by all urologic surgeons. It requires a highly skilled urologic surgeon who has extensive experience using an operating microscope and doing testicular sperm retrievals. In addition, it requires a fertility laboratory with experienced and well-trained staff. Together, the surgeon’s and laboratory’s skill and experience is key to the success of this procedure (5).
- Caroppo E, Colpi EM et al. The seminiferous tubule caliber pattern as evaluated at high magnification during microdissection testicular sperm extraction predicts sperm retrieval in patients with non-obstructive azoospermia. Andrology 2019; 7: 8-14
- Ghalayini IF, A-Ghazo M, et al. Clinical Comparison of Conventional Testicular Sperm Extraction and Microdissection Techniques for Non-Obstructive Azoospermia. J Clin Med Res. 2011; 3(3): 124-131.
- Ravissini PC, Azevedo M, et al. Success rate in ICSI treatment of men with non-obstructive azoospermia (NOA): a comparative study between TESE (testicular sperm extraction) and microdissection-TESE. Fertil Steril. 2008; 90: S382-S383.
- Ohlander S, Hotaling J, et al. Impact of fresh versus cryopreserved testicular sperm upon intracytoplasmic sperm injection pregnancy outcomes in men with azoospermia due to spermatogenic dysfunction: a meta-analysis. Fertil Steril. 2014; 101(2): 344-349.
- Ishikawa T, Nose R, et al. Learning curves of microdissection testicular sperm extraction for nonobstructive azoospermia. Fertil Steril 2010; 94(3): 1008-1011.