

If you've recently been told you have azoospermia, seeing the words "zero sperm" on a semen analysis can feel devastating. I have this conversation with men almost every day, and I know how overwhelming it is. Over the past two decades, one surgical procedure has dramatically changed the outlook for many men with non-obstructive azoospermia (NOA): microdissection testicular sperm extraction, or mTESE.

Before discussing the surgery itself, it's important to understand who it is designed to help. There are two broad types of azoospermia. Obstructive azoospermia (OA) occurs when sperm production is normal, but a blockage prevents sperm from reaching the ejaculate. Men with vasectomies, congenital absence of the vas deferens, or ejaculatory duct obstruction fall into this category. These men almost always have sperm available within the testicle or epididymis. Non-obstructive azoospermia, however, is different. In NOA, the testicle has difficulty producing sperm. This may result from genetic conditions, previous chemotherapy, undescended testicles, severe varicoceles, testicular injury, hormonal disorders, or sometimes causes we never identify. mTESE is designed specifically for these men.

The reason mTESE works is that sperm production in men with NOA is often patchy rather than completely absent. Under a microscope, one tiny area of the testicle may contain active sperm production while the surrounding tissue contains none. Standard testicular sperm extraction (TESE) removes random pieces of testicular tissue, hoping to find one of these rare areas. mTESE takes a very different approach. Using an operating microscope with 15–25× magnification, the surgeon systematically examines the seminiferous tubules and selectively removes the larger, healthier-appearing tubules that are most likely to contain sperm. This targeted approach allows for higher sperm retrieval rates while removing less healthy testicular tissue, reducing damage to the testicle.

The success of mTESE depends almost entirely on the underlying diagnosis, not simply on the surgeon's technique. Across multiple studies, the overall sperm retrieval rate for men with NOA ranges between 40% and 60%, with most large contemporary series reporting approximately 50%. That means roughly half of appropriately selected men undergoing mTESE will have sperm successfully retrieved that can be used for intracytoplasmic sperm injection (ICSI). While those odds may sound discouraging at first, remember that before mTESE existed, nearly all of these men would have been told they had no chance of fathering a biological child.

Not every diagnosis carries the same prognosis. Men with hypospermatogenesis, where sperm production is reduced but still occurring throughout much of the testicle, have the highest retrieval rates, often 70–100%. Men with late maturation arrest generally have intermediate success rates, often between 40% and 70%, depending on the severity. Men with Sertoli cell-only syndrome (SCOS) present one of the greatest challenges. Although many pathology reports describe complete absence of germ cells, sperm production can still exist in tiny isolated areas that are missed during biopsy. Even in SCOS, experienced centers report retrieval rates of approximately 20–40%.

Genetics also play a major role in predicting success. Men with Klinefelter syndrome (47,XXY) were once considered universally infertile. Today, mTESE has changed that outlook dramatically, with sperm retrieval rates approaching 40–60% in experienced hands, particularly in younger men. In contrast, men with complete AZFa or AZFb Y chromosome microdeletions have an extremely poor prognosis, with sperm retrieval approaching 0% in most published series. Men with isolated AZFc deletions, however, often have much better outcomes, with retrieval rates reported between 50% and 70%.

One of the biggest misconceptions I encounter is that a very high FSH means mTESE will not work. While elevated FSH reflects the brain working harder to stimulate damaged testicles, it does not reliably predict whether sperm can be found. I have successfully retrieved sperm in men with FSH levels above 40 IU/L, while occasionally failing in men whose hormone levels were nearly normal. Similarly, small testicular volume does not automatically mean there is no chance of success. Hormones provide clues, but they should never be used alone to determine whether someone is a candidate for surgery.

Patients frequently ask whether anything can improve their chances before surgery. In men with secondary hypogonadism, treating hormonal deficiencies with hCG, clomiphene citrate, enclomiphene, or aromatase inhibitors may improve intratesticular testosterone and, in some cases, sperm production. Men with clinically significant varicoceles may also benefit from repair before considering mTESE, particularly if there is evidence of residual spermatogenesis. Optimizing sleep, weight, exercise, nutrition, and avoiding anabolic steroids, smoking, and excessive alcohol are also reasonable recommendations, although none guarantee successful sperm retrieval.

The procedure itself is usually performed under general anesthesia and typically lasts between 2 and 4 hours, depending on the complexity of the case. A small incision is made in the scrotum, and the operating microscope is used to carefully inspect both testicles. Tissue samples are immediately examined by experienced embryologists or andrology laboratory staff looking for sperm. If sperm are identified, they are either used fresh for IVF/ICSI or cryopreserved for future use. Because sperm may be extremely limited, every sperm cell matters, and close coordination between the surgeon and embryology laboratory is critical.

Recovery from mTESE is generally easier than many men expect. Most patients experience soreness and swelling for several days and return to desk work within a week. Heavy lifting, strenuous exercise, and sexual activity are typically avoided for approximately 2–3 weeks. Long-term complications are uncommon but can include hematoma, infection, chronic discomfort, and temporary declines in testosterone. Most studies demonstrate that testosterone levels decrease modestly during the first few months after surgery but recover in the majority of men within 6–18 months. Men with pre-existing low testosterone or Klinefelter syndrome require closer follow-up because they are at greater risk for persistent hypogonadism.

One question I encourage every patient to ask before surgery is: Who will be examining my tissue? mTESE is only as good as the laboratory supporting it. Identifying rare sperm among thousands of seminiferous tubules requires experienced embryologists who understand testicular tissue. Some centers also perform advanced sperm search techniques, such as extended sperm search or prolonged microscopic examination, which may increase the likelihood of finding rare sperm in selected patients. Choosing an experienced reproductive urologist working alongside an experienced IVF laboratory often makes a significant difference.

Emotionally, mTESE can be one of the most difficult experiences a couple goes through. Unlike many surgeries, you often wake up not simply wondering how the operation went, you want to know whether your future family changed that day. Some couples receive wonderful news that sperm were found. Others learn that despite everyone's best efforts, none could be identified. Neither outcome reflects something you did or failed to do. Many causes of NOA are genetic or developmental, completely outside your control.

Perhaps the most important message I want every man reading this to hear is that azoospermia is not a diagnosis, it is a starting point. Twenty-five years ago, many men with NOA were told donor sperm was their only option. Today, thanks to mTESE and advances in assisted reproduction, thousands of men with conditions once considered untreatable have become biological fathers. While no surgeon can promise success, modern reproductive urology offers hope where very little existed before.

If you have been diagnosed with azoospermia, seek evaluation from a reproductive urologist, not just a general urologist. Make sure you've had a complete workup, including repeat semen analyses, hormone testing, genetic evaluation when indicated, and a thorough physical examination. Understand your specific diagnosis, ask about your expected retrieval rate based on published data, and don't hesitate to seek a second opinion if you have questions.

Hope should always be grounded in science, but it should never disappear simply because the first semen analysis showed zero sperm.

# References

1. Schlegel PN. Testicular sperm extraction: microdissection improves sperm yield with minimal tissue excision. *Hum Reprod.* 1999;14(1):131-135.
2. Bernie AM, Mata DA, Ramasamy R, Schlegel PN. Comparison of microdissection testicular sperm extraction versus conventional testicular sperm extraction in men with non-obstructive azoospermia: a systematic review and meta-analysis. *Fertil Steril.* 2015;104(5):1099-1103.
3. Corona G, Minhas S, Giwercman A, et al. Sperm recovery and ICSI outcomes in non-obstructive azoospermia: a systematic review. *Hum Reprod Update.* 2019;25(6):733-757.
4. Schlegel PN, Sigman M, Collura B, et al. Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline. *J Urol.* 2021;205:36-43.
5. EAU Guidelines on Sexual and Reproductive Health. European Association of Urology. 2025 Edition.
6. Ramasamy R, Yagan N, Schlegel PN. Structural and functional changes to the testis after microdissection TESE. *J Urol.* 2005;174:102-105.
7. Okada H, Dobashi M, Yamazaki T, et al. Conventional versus microdissection testicular sperm extraction for non-obstructive azoospermia. *Hum Reprod.* 2002;17(11):2924-2929.
8. Majzoub A, Agarwal A. The role of microdissection testicular sperm extraction in non-obstructive azoospermia. *World J Mens Health.* 2023;41(2):191-207.

mTESE Explained: What Every Man With Non-Obstructive Azoospermia Should Know About Microdissection Testicular Sperm Extraction