MicroTESE Success Predictors: What Affects the Chance of Finding Sperm?
If you have been diagnosed with non-obstructive azoospermia (NOA) and are considering MicroTESE, one of the most common questions is:
“What is my chance of finding sperm?”
It is an important question, but there is currently no single blood test, scan or examination finding that can accurately predict the outcome for an individual man.
Microdissection testicular sperm extraction, usually called MicroTESE or micro-TESE, involves examining testicular tissue under an operating microscope to identify areas that may contain sperm.
In men with non-obstructive azoospermia, sperm production can be extremely patchy. Small areas of sperm production may remain even when the overall function of the testicle is severely impaired.[1-4]
Current European Association of Urology guidance states that no definitive pre-operative clinical or biochemical predictor can reliably determine whether sperm will be retrieved during MicroTESE.[1]
Some findings are nevertheless useful when estimating the likely outcome. Genetics can sometimes provide particularly important information, while factors such as FSH and testicular size are less reliable than many patients expect.
For an overview of the procedure itself, see MicroTESE for Azoospermia.
What Does MicroTESE Success Mean?
When discussing MicroTESE, it is important to distinguish sperm retrieval from IVF success.
A successful MicroTESE generally means that sperm suitable for use in assisted reproduction have been identified within the retrieved testicular tissue.
Finding sperm does not automatically mean that fertilisation, pregnancy or live birth will occur.
If sperm are retrieved, they are generally used with IVF and intracytoplasmic sperm injection (ICSI). Subsequent outcomes depend on additional factors including egg quality, female reproductive factors, embryology, embryo development and the circumstances of the couple undergoing treatment.[2,3]
Published MicroTESE sperm retrieval rates vary considerably between studies and patient groups. Across systematic reviews, sperm are found in approximately 40–50% of men with non-obstructive azoospermia overall.[1,5,6]
This is a population estimate rather than an individual prediction. Some men have a substantially higher likelihood of sperm retrieval, while others have a much lower likelihood.
What Are the Main Predictors of MicroTESE Success?
The most useful way to assess the likelihood of sperm retrieval is to consider several factors together.
These include:
the underlying cause of azoospermia
genetic testing
previous sperm retrieval procedures
FSH and other hormone results
testicular size and examination findings
previous testicular histology, if available
previous chemotherapy, radiotherapy or testicular surgery
previous undescended testes
relevant medical and reproductive history
No single factor should usually be considered in isolation.
Genetics and MicroTESE Success
Genetic testing is particularly important in men with severe impairment of sperm production because certain genetic findings can significantly alter the expected outcome.
Complete AZFa and AZFb Y-Chromosome Deletions
Complete AZFa or AZFb deletions are among the clearest predictors of unsuccessful sperm retrieval.
Men with complete deletions of these regions have an extremely low likelihood of sperm being present within the testes.
Current EAU guidance recommends against attempting testicular sperm retrieval in men with complete AZFa or complete AZFb deletions.[1]
This is one reason genetic assessment should ideally occur before MicroTESE rather than after an unsuccessful operation.
AZFc Deletions
AZFc deletions are different.
Sperm production may remain in parts of the testes, and testicular sperm can be retrieved in a significant proportion of affected men.
The EAU guideline reports testicular sperm retrieval in approximately 50–75% of men with AZFc deletion.[1]
A 2024 systematic review involving 441 men with azoospermia and AZFc deletions reported sperm retrieval in approximately 62% overall, although outcomes varied considerably between individual studies.[7]
Because an AZFc deletion can be transmitted to male offspring, genetic counselling should form part of treatment planning before assisted reproduction.[1]
Klinefelter Syndrome
Men with Klinefelter syndrome commonly have very small testes, high FSH and azoospermia.
Despite this, small areas of sperm production can sometimes remain within the testes.
Systematic reviews have shown that sperm can be retrieved in a meaningful proportion of appropriately selected men with Klinefelter syndrome.[8]
Age, hormone levels and other clinical factors may provide additional information, but they cannot reliably determine the result for an individual patient.
For further information, see Male Infertility Genetic Testing.
Does a High FSH Mean MicroTESE Will Fail?
No.
This is one of the most important misconceptions surrounding MicroTESE.
FSH, or follicle-stimulating hormone, is produced by the pituitary gland and stimulates sperm production within the testes.
When sperm production is significantly impaired, FSH commonly increases as the body attempts to stimulate the testes more strongly.
A high FSH therefore provides useful evidence that sperm production is impaired.
However, it cannot tell us whether small areas of sperm production remain somewhere within the testicle.
MicroTESE is specifically designed to search for these focal areas.
The EAU guideline notes that men with non-obstructive azoospermia and elevated FSH may still have areas of spermatogenesis that can be identified during surgical sperm retrieval.[1]
A meta-analysis examining FSH, testicular volume and testicular histology also found that FSH had relatively limited ability to predict MicroTESE success.[4]
More recent research has reached a similar conclusion. Men with successful retrieval may, on average, have somewhat lower FSH levels, but FSH cannot reliably determine whether an individual operation will succeed.[6]
There is therefore no universally accepted FSH level above which MicroTESE automatically becomes futile.
Can MicroTESE Work With Very Small Testicles?
Yes.
Smaller testicular volume often reflects more severe impairment of sperm production, but testicular size alone does not determine whether sperm will be found.
MicroTESE searches for isolated areas where sperm production may still be occurring.
As a result, sperm can occasionally be retrieved from very small testes.
The opposite is also important: having normal-sized testes does not guarantee successful sperm retrieval.
Studies suggest that testicular volume has some relationship with overall testicular function, but it remains a relatively weak predictor of MicroTESE outcome when used alone.[4,9]
Testicular size is therefore one part of the assessment rather than a reason by itself to recommend or reject surgery.
Does Testosterone Predict MicroTESE Success?
Testosterone is an important component of the evaluation of azoospermia, but it does not reliably predict MicroTESE success by itself.
Some studies have found associations between testosterone levels and sperm retrieval, particularly within certain patient groups such as men with Klinefelter syndrome.[8]
However, these associations are not accurate enough to establish a testosterone level that reliably separates men who will have successful MicroTESE from those who will not.
Hormonal assessment is particularly useful for identifying whether a potentially treatable endocrine disorder is contributing to azoospermia.
This distinction matters because azoospermia caused by inadequate hormonal stimulation of the testes is fundamentally different from primary testicular failure.
External testosterone can also suppress the hormonal signals required for sperm production. Testosterone replacement therapy should therefore not be started as a treatment for male infertility without appropriate specialist assessment.
Can AMH Predict MicroTESE Success?
Anti-Müllerian hormone, or AMH, is being investigated as a possible marker of sperm retrieval.
A 2024 systematic review and meta-analysis found an association between AMH levels and the likelihood of successful sperm retrieval in men undergoing MicroTESE for non-obstructive azoospermia.[6]
This is an interesting development, but AMH is not yet an accurate standalone MicroTESE test.
Research studies have used different laboratory methods, patient populations and threshold values. There is currently no universally accepted AMH cut-off that can reliably determine whether MicroTESE should or should not be performed.
Inhibin B has also been investigated as a marker of sperm production, but current evidence does not support using it alone to predict an individual MicroTESE result.[6]
These markers may become more useful in the future as prediction models improve.
Why the Cause of Azoospermia Matters
Non-obstructive azoospermia is not a single disease.
It describes a situation in which no sperm are detected in the ejaculate because sperm production within the testes is severely impaired.
Possible causes include:
genetic conditions
previous undescended testes
previous chemotherapy
previous radiotherapy
testicular torsion or injury
severe testicular infection
previous testicular surgery
severe primary testicular failure
some hormonal disorders
cases where no definite cause can be identified
MicroTESE outcomes vary between these groups.
For example, some studies have reported relatively favourable sperm retrieval outcomes among selected men with a history of previously undescended testes.[9]
This is why simply quoting the same MicroTESE success rate to every patient with non-obstructive azoospermia can be misleading.
A more useful approach is to establish why azoospermia has occurred before estimating likely treatment outcomes.
Read more in Azoospermia: Diagnosis and Treatment.
Does Testicular Histology Predict MicroTESE Success?
If testicular tissue has previously been examined, the histological pattern can provide useful information.
The main patterns encountered include hypospermatogenesis, maturation arrest and Sertoli-cell-only syndrome.
Hypospermatogenesis
Hypospermatogenesis means that sperm production is occurring but at a substantially reduced level.
This generally has the most favourable association with sperm retrieval because some degree of sperm production is already known to be present.[4,9]
Maturation Arrest
Maturation arrest occurs when developing sperm cells stop progressing at a particular stage.
MicroTESE outcomes are more variable in this group.
Sertoli-Cell-Only Syndrome
In Sertoli-cell-only syndrome, many seminiferous tubules do not contain germ cells.
Sperm retrieval rates are generally lower than with hypospermatogenesis, although focal sperm production may still occur and successful MicroTESE remains possible in selected patients.[4,9]
Importantly, a separate diagnostic testicular biopsy is generally not recommended simply to predict whether a subsequent MicroTESE will succeed.
Histology is most useful when information already exists from a previous biopsy, TESE or sperm retrieval procedure.[1,2]
What If a Previous TESE or TESA Did Not Find Sperm?
A previous unsuccessful sperm retrieval is important, but the exact procedure matters.
TESA, conventional TESE and MicroTESE are different techniques.
A failed needle aspiration or conventional TESE does not necessarily mean MicroTESE will also fail.
MicroTESE uses an operating microscope to examine the testicular tissue systematically and identify seminiferous tubules that appear more likely to contain sperm.
Current AUA/ASRM and EAU guidance supports MicroTESE as the preferred surgical sperm retrieval technique for men with non-obstructive azoospermia.[1-3]
After an unsuccessful previous procedure, useful information includes:
the type of sperm retrieval performed
whether one or both testes were explored
the operative report
embryology findings
the amount of tissue examined
any available histology
the underlying diagnosis
What About Repeat MicroTESE After a Previous Failed MicroTESE?
A previous failed MicroTESE is a more difficult situation.
Repeat or salvage MicroTESE may still identify sperm in selected men, but the expected likelihood is generally lower and depends heavily on the circumstances of the first operation.[10]
The original operative technique, histology, underlying diagnosis and whether any potentially reversible factors have been identified should all be reviewed before considering another procedure.
A systematic review of salvage MicroTESE found that men with evidence of hypospermatogenesis generally had more favourable subsequent retrieval outcomes than men with Sertoli-cell-only syndrome or maturation arrest.[10]
Repeat MicroTESE therefore requires individual assessment rather than simply repeating the original procedure.
Can Medication Improve MicroTESE Success?
There is considerable interest in hormonal treatment before MicroTESE.
For most men with typical non-obstructive azoospermia due to primary testicular failure, current evidence does not support routinely giving hormonal treatment simply to increase the sperm retrieval rate.
The EAU guideline concludes that evidence for hormonal stimulation before surgical sperm retrieval remains inconclusive and advises against routine hormonal stimulation before TESE or MicroTESE in men with hypergonadotropic hypogonadism.[1]
There are exceptions.
Men with a genuine hormonal disorder may require medical treatment rather than immediate sperm retrieval.
Men who have been taking external testosterone or anabolic steroids may also require a different pathway because these medications can suppress sperm production.
The aim should therefore be to identify a treatable underlying problem when one exists, rather than prescribing hormonal medication to every man before MicroTESE.
What Are the Most Useful MicroTESE Success Predictors?
The evidence suggests that MicroTESE prediction should be based more on the underlying diagnosis than on a single laboratory number.
A very high FSH does not necessarily mean MicroTESE will fail.
Very small testes do not necessarily mean MicroTESE will fail.
Normal testosterone does not guarantee that sperm will be found.
Normal-sized testes do not guarantee success.
AMH and inhibin B cannot yet accurately predict an individual result.
Genetic findings can sometimes provide much stronger information. Complete AZFa and AZFb Y-chromosome deletions are the clearest examples, because current guidelines recommend against attempting sperm retrieval in these situations.[1]
For most other men with non-obstructive azoospermia, several clinical factors need to be considered together.
What Should Be Checked Before MicroTESE?
Before proceeding to MicroTESE, the first priority is confirming the diagnosis and ensuring that MicroTESE is actually the appropriate treatment.
Assessment will commonly include semen analyses, reproductive history, medical and surgical history, examination, hormonal testing and appropriate genetic investigation.
Previous fertility treatment, previous sperm retrieval procedures and any available histology should also be reviewed.
It is also important to distinguish non-obstructive azoospermia from obstructive azoospermia.
Men with an obstruction may have normal sperm production and may be better suited to a different sperm retrieval procedure or, in selected cases, reconstructive surgery.
For an overview of the different techniques, see Surgical Sperm Retrieval.
MicroTESE Assessment in Brisbane
For patients in Brisbane and South-East Queensland, assessment before MicroTESE can include review of semen analyses, hormone testing, genetics, examination findings and previous fertility treatment.
The aim is not simply to decide whether surgery can be performed.
It is to establish why azoospermia has occurred, identify any potentially reversible factors, assess whether MicroTESE is appropriate and coordinate sperm retrieval with the patient's chosen fertility clinic and embryology laboratory.
Learn more about Male Infertility and Reproductive Urology.
Travelling Interstate for MicroTESE
Patients travelling from regional Queensland or interstate Australia can often complete much of the initial assessment before travelling to Brisbane.
Useful records include previous semen analyses, hormone results, genetic testing, ultrasound reports, fertility-clinic correspondence and reports from any previous sperm retrieval procedures.
Reviewing these documents before surgery can help determine whether further investigation is needed and assist with coordination between the surgical and IVF teams.
International Patients Considering MicroTESE
International patients require additional planning because MicroTESE needs to be coordinated with fertility treatment and an embryology laboratory.
Ideally, the diagnosis should be reviewed before committing to flights, accommodation or an IVF cycle.
Previous semen analyses, hormone results, genetic investigations and sperm retrieval records can often be reviewed remotely before travelling.
The timing of sperm retrieval will depend on whether sperm are intended to be frozen or coordinated with egg retrieval and fresh IVF/ICSI treatment.
International patients can review the International MicroTESE pathway.
Frequently Asked Questions About MicroTESE Success
What Is the Average MicroTESE Success Rate?
Published results vary according to the underlying diagnosis, genetics, patient selection, surgical technique and laboratory factors.
Across major analyses, sperm are retrieved in approximately 40–50% of men with non-obstructive azoospermia overall.[1,5,6]
This should not be interpreted as an individual patient's predicted probability.
Can MicroTESE Work If My FSH Is Over 20 or 30?
Yes.
There is no accepted FSH threshold above which focal sperm production can be reliably excluded.
Men with markedly elevated FSH may still have sperm found during MicroTESE.[1,4,6]
Can MicroTESE Work With Very Small Testicles?
Yes.
Small testes are associated with impaired sperm production but do not prove that sperm are completely absent.
MicroTESE is designed to identify small areas of preserved sperm production that may not be reflected by overall testicular size.[4]
Which Blood Test Best Predicts MicroTESE Success?
There is currently no blood test that accurately predicts MicroTESE success for an individual man.
FSH provides useful diagnostic information but is a relatively weak predictor of sperm retrieval.
AMH is an emerging marker with promising research findings, but it is not sufficiently validated to determine whether an individual patient should proceed with surgery.[1,6]
What Is the Strongest Predictor of MicroTESE Failure?
Certain genetic abnormalities provide the clearest prognostic information.
Complete AZFa and complete AZFb Y-chromosome deletions are associated with an extremely low likelihood of sperm retrieval, and current guidelines recommend against attempting testicular sperm retrieval in these situations.[1]
Does Finding Sperm Mean IVF Will Work?
No.
Finding sperm and achieving a pregnancy are separate outcomes.
Once sperm have been retrieved, fertilisation, embryo development, pregnancy and live birth depend on multiple additional factors involving both partners and the IVF process.[3,5]
When to Consider a Specialist MicroTESE Assessment
If you have azoospermia and have been advised to consider MicroTESE, a specialist reproductive urology assessment can help clarify why sperm are absent and whether surgical sperm retrieval is appropriate.
Assessment may be particularly useful if you have:
non-obstructive azoospermia
very high FSH
small testes
Klinefelter syndrome
a Y-chromosome microdeletion
previous chemotherapy or radiotherapy
a history of undescended testes
a previous unsuccessful TESA or TESE
a previous failed MicroTESE
uncertainty about whether the azoospermia is obstructive or non-obstructive
For local Brisbane, regional Queensland, interstate and international patients, existing test results and previous fertility records can be reviewed as part of the assessment.
Request a Male Fertility Appointment
References
European Association of Urology. EAU Guidelines on Sexual and Reproductive Health: Male Infertility. Arnhem: EAU Guidelines Office; 2026.
Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ, et al. Diagnosis and treatment of infertility in men: AUA/ASRM guideline part I. Fertil Steril. 2021;115(1):54-61.
Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ, et al. Diagnosis and treatment of infertility in men: AUA/ASRM guideline part II. Fertil Steril. 2021;115(1):62-69.
Li H, Chen LP, Yang J, Li MC, Chen RB, Lan RZ, et al. Predictive value of FSH, testicular volume, and histopathological findings for the sperm retrieval rate of microdissection TESE in nonobstructive azoospermia: a meta-analysis. Asian J Androl. 2018;20(1):30-36.
Corona G, Minhas S, Giwercman A, Bettocchi C, Dinkelman-Smit M, Dohle G, et al. Sperm recovery and ICSI outcomes in men with non-obstructive azoospermia: a systematic review and meta-analysis. Hum Reprod Update. 2019;25(6):733-757.
Pozzi E, Corsini C, Belladelli F, Bertini A, Negri F, Raffo M, et al. Role of follicle-stimulating hormone, inhibin B, and anti-Müllerian hormone in predicting sperm retrieval from men with nonobstructive azoospermia undergoing microdissection testicular sperm extraction: a systematic review and meta-analysis. Eur Urol Open Sci. 2024;65:3-12.
Jiao ZY, Li MR, Zhuo L, Fang YY, Pan JY, Hong K. Sperm retrieval rate and patient factors in azoospermia factor c microdeletion azoospermia: a systematic review. BJU Int. 2024;134(1):6-12.
Majzoub A, Arafa M, Clemens H, Imperial J, Leisegang K, Khalafalla K, et al. A systematic review and meta-analysis exploring the predictors of sperm retrieval in patients with non-obstructive azoospermia and chromosomal abnormalities. Andrologia. 2022;54(3):e14303.
Arshad MA, Majzoub A, Esteves SC. Predictors of surgical sperm retrieval in non-obstructive azoospermia: summary of current literature. Int Urol Nephrol. 2020;52(11):2015-2038.
Zhang F, et al. Predictors of successful salvage microdissection testicular sperm extraction after failed initial TESE in patients with non-obstructive azoospermia: a systematic review and meta-analysis. Andrology. 2024;12.
Brannigan RE, Hermanson L, Kaczmarek J, Kim SK, Kirkby E, Tanrikut C. Updates to Male Infertility: AUA/ASRM Guideline (2024). J Urol. 2024;212(6):789-799.
Medical Disclaimer
This article provides general educational information only and does not provide individual medical advice, diagnosis or treatment recommendations.
MicroTESE is not appropriate for every person with azoospermia. The likelihood of sperm retrieval depends on individual clinical circumstances, and sperm retrieval cannot be guaranteed. Finding sperm does not guarantee fertilisation, embryo development, pregnancy or live birth.
Investigation and treatment of infertility should consider the reproductive circumstances of both partners where applicable and should be coordinated with appropriately qualified fertility and embryology professionals.
Do not start, stop or alter prescribed medication, testosterone or hormonal treatment on the basis of information in this article. Individual treatment decisions should be made following appropriate medical assessment and discussion of the potential benefits, risks and alternatives.
