What Causes Male Infertility? Causes, Diagnosis and Treatment
Updated: Aug 26
What Causes Male Infertility?
Male infertility can result from problems with sperm production, sperm quality, sperm transport, hormones, or sexual and reproductive function. In some men, a specific cause can be identified and treated, while in others, several factors may contribute to reduced fertility.
Understanding the causes of male infertility is an important first step toward choosing the right investigations and treatment.
Infertility is generally defined as the inability to achieve a pregnancy after 12 months of regular, unprotected intercourse. Current European Association of Urology guidance recommends evaluating both partners and specifically assessing the male partner when a couple seeks medical help for fertility problems. A male-associated factor is identified in around half of couples experiencing infertility. (Uroweb)
The subject has also been an important area of discussion in sexual and reproductive medicine. The European Society for Sexual Medicine's 2014 scientific programme included a dedicated symposium on male infertility covering testosterone supplementation, obesity and metabolic syndrome, micro-TESE, varicocele surgery, surgical treatment of male infertility, idiopathic male infertility, and oxidative stress and sperm DNA damage. (ESSM)
What Is Male Infertility?
Male infertility refers to difficulty achieving pregnancy when the male partner has a reproductive problem that may reduce the couple's chances of conception.
This does not necessarily mean that a man produces no sperm. Fertility can be affected by:
A low sperm count
Poor sperm movement
Abnormal sperm morphology
Problems with sperm production
Blockage of the reproductive tract
Hormonal disorders
Varicocele
Genetic conditions
Certain medical treatments
Erectile or ejaculation disorders
Other factors affecting reproductive health
Importantly, fertility is a couple-based issue. A man can have relatively normal semen parameters while the couple still experiences unexplained infertility, which is why both partners should be assessed when appropriate. (Uroweb)
The Most Common Causes of Male Infertility
There is no single cause of male infertility. A specialist evaluation looks at several different areas to determine what may be affecting reproductive function.
1. Problems With Sperm Production
The testicles are responsible for producing sperm. If sperm production is impaired, the semen may contain fewer sperm, sperm with reduced movement, or no sperm at all.
Conditions that can affect sperm production include:
Testicular disorders
Previous testicular injury
Undescended testes
Hormonal abnormalities
Certain genetic conditions
Some infections
Chemotherapy or other gonadotoxic treatments
Certain medications or anabolic steroids
The severity of the problem can vary considerably from one man to another.
For this reason, a semen analysis is an important part of the initial evaluation, but its results need to be interpreted together with the patient's medical history, examination and, when necessary, additional investigations. Current EAU guidance specifically notes that semen analysis alone cannot distinguish fertile from infertile men. (Uroweb)
2. Low Sperm Count
A low sperm count, also called oligozoospermia, means that the concentration or total number of sperm is below the laboratory's reference range.
A low sperm count does not automatically mean that natural conception is impossible. The overall picture also depends on sperm movement, morphology, the severity of the reduction and the fertility of the female partner.
Possible causes include hormonal disorders, varicocele, genetic abnormalities, testicular problems, certain medications and lifestyle or environmental factors.
If an initial semen analysis is abnormal, current European guidance recommends repeating semen analysis rather than making conclusions from a single result. (Uroweb)
3. Azoospermia
Azoospermia means that no sperm are detected in the ejaculate.
This does not always mean that the testicles are unable to produce sperm.
Azoospermia is broadly divided into:
Obstructive azoospermia
Sperm production may be occurring normally, but a blockage prevents sperm from reaching the semen.
Non-obstructive azoospermia
The main problem is impaired sperm production within the testicles.
Determining which type is present is essential because the diagnostic approach and potential treatment options are different.
The ESSM 2014 programme specifically addressed micro-TESE and sperm retrieval, including predictors of sperm retrieval and management after unsuccessful micro-TESE. (ESSM)
Current EAU guidance also recommends a comprehensive evaluation for men with non-obstructive azoospermia, including medical history, hormonal assessment, genetic testing and appropriate imaging. (Uroweb)
4. Varicocele
A varicocele is an enlargement of the veins around the testicle.
It is a common finding in men and may be associated with impaired sperm production and male infertility in some patients.
The relationship between varicocele and fertility is complex. Not every man with a varicocele needs treatment.
The decision to treat depends on factors such as:
Whether the varicocele is clinically significant
Semen analysis results
Symptoms
Testicular findings
The couple's fertility goals
Other causes of infertility
Varicocele was specifically discussed in the ESSM scientific programme, including its relationship with non-obstructive azoospermia, pain, androgen deficiency and advanced testicular dysfunction, as well as current approaches to varicocele surgery. (ESSM)
5. Hormonal Problems
Hormones play an essential role in sperm production.
The reproductive system relies on communication between the brain, pituitary gland and testicles. Problems affecting this hormonal pathway can interfere with sperm production and fertility.
A hormonal assessment may therefore be recommended, particularly when semen analysis shows significant abnormalities or when there are symptoms suggesting an endocrine problem.
One particularly important issue is testosterone treatment.
Can Testosterone Treatment Affect Fertility?
Yes.
Men who are trying to conceive should not assume that testosterone treatment will improve fertility.
External testosterone can suppress the hormonal signals that stimulate sperm production and may significantly reduce sperm production.
Current EAU guidance specifically recommends against using testosterone therapy to treat male infertility or in men who wish to become fathers. (Uroweb)
This topic was also included in the ESSM 2014 male infertility symposium, which featured a presentation on the effects of testosterone supplements in male infertility. (ESSM)
6. Obesity and Metabolic Health
Male reproductive health is closely connected with overall health.
Obesity and metabolic disorders can be associated with changes in hormonal function and may affect reproductive health.
The ESSM 2014 programme included a specific presentation on obesity, metabolic syndrome and the male reproductive system, highlighting the importance of considering metabolic health when evaluating male fertility. (ESSM)
A fertility assessment may therefore consider factors such as:
Body weight
Diabetes
Metabolic syndrome
Blood pressure
General medical conditions
Lifestyle factors
Improving general health may be an important part of an individual's fertility plan, although lifestyle changes should not be viewed as a substitute for investigating an identifiable medical cause.
7. Sperm DNA Damage and Oxidative Stress
Traditional semen analysis evaluates characteristics such as sperm concentration, movement and morphology.
However, sperm health can involve additional biological factors.
Oxidative stress occurs when reactive oxygen species exceed the body's ability to control them. Excess oxidative stress may affect sperm function and DNA integrity.
The ESSM programme included a dedicated presentation on oxidative stress, sperm DNA damage and apoptosis in male reproductive cells. (ESSM)
Modern guidelines recognise sperm DNA fragmentation as a more specialised investigation rather than a routine test for every infertile man. Current EAU guidance recommends considering sperm DNA fragmentation testing in selected situations, including recurrent pregnancy loss, failure of assisted reproductive treatment and unexplained infertility. (Uroweb)
8. Genetic Causes of Male Infertility
Genetic abnormalities can affect sperm production, the development of the reproductive system or the transport of sperm.
Genetic testing is particularly important in men with severe abnormalities in sperm production, including some men with azoospermia or very severe oligozoospermia.
Depending on the clinical situation, testing may include chromosome analysis and specific genetic tests.
Current EAU recommendations include genetic evaluation for selected men with severe sperm-production problems. (Uroweb)
Identifying a genetic cause can be important not only for diagnosis but also for treatment planning and counselling about reproductive options.
9. Previous Surgery, Injury or Infection
A man's previous medical history can provide important clues about fertility.
Potential factors include:
Previous testicular surgery
Testicular trauma
Undescended testicles
Genitourinary infections
Previous hernia surgery
Vasectomy
Treatments that may have affected sperm production
Exposure to chemotherapy or radiation
Some of these factors can affect sperm production, while others may interfere with the transport of sperm.
This is why a detailed medical and reproductive history is an essential part of a male fertility assessment. Current EAU guidance specifically recommends reviewing previous surgery, infections, trauma, medications, systemic disease and lifestyle or behavioural factors. (Uroweb)
10. Erectile and Ejaculation Problems
Male fertility depends not only on sperm production but also on the ability to have intercourse and deliver semen.
Conditions such as:
Erectile dysfunction
Ejaculatory disorders
Anejaculation
Retrograde ejaculation
may interfere with natural conception.
In some cases, the sperm production itself may be normal, but sperm cannot be effectively delivered into the reproductive tract.
This is one of the reasons male infertility and sexual medicine frequently overlap.
How Is Male Infertility Diagnosed?
The goal of a fertility assessment is not simply to determine whether sperm are present.
The more important question is:
Why is fertility reduced, and is there a treatable cause?
A typical evaluation may include several steps.
Medical and Reproductive History
The specialist may ask about:
Previous pregnancies
Duration of infertility
Previous testicular problems
Childhood conditions
Surgery
Infections
Medications
Testosterone or anabolic steroid use
Medical conditions
Lifestyle factors
Family history
Physical Examination
The examination may assess:
Testicular size and consistency
Presence of both testes
Epididymis
Vas deferens
Presence of varicocele
Signs of hormonal abnormalities
Other abnormalities of the reproductive system
Current EAU guidance considers a focused physical examination an essential part of male infertility evaluation. (Uroweb)
Semen Analysis
Semen analysis is one of the key investigations used to assess male reproductive potential.
It can provide information about:
Semen volume
Sperm concentration
Total sperm number
Sperm motility
Sperm morphology
Sperm vitality when indicated
However, a semen analysis should not be interpreted as a simple fertile vs infertile test. Current guidance emphasises that individual semen parameters do not by themselves establish fertility or infertility. (Uroweb)
If the first analysis is abnormal, repeat testing may be recommended.
Hormonal Tests
Blood tests may be used to evaluate reproductive hormones, particularly when sperm production is significantly impaired or there are symptoms suggesting an endocrine disorder.
Depending on the situation, the assessment may include hormones such as:
Testosterone
FSH
LH
Other hormones when clinically indicated
Current EAU guidance recommends hormonal evaluation in men with oligozoospermia and azoospermia. (Uroweb)
Genetic Testing and Imaging
Additional investigations are not necessary for every patient.
They may be recommended when the semen analysis, examination or medical history suggests a specific condition.
These can include:
Genetic testing
Scrotal ultrasound
Imaging of the reproductive tract
Advanced sperm testing
Other specialised investigations
The aim is to avoid unnecessary testing while making sure important causes are not overlooked.
Can Male Infertility Be Treated?
Yes, in many cases male infertility can be treated or managed.
The treatment depends entirely on the underlying cause.
Depending on the diagnosis, treatment may involve:
Medical treatment
For selected hormonal or medical conditions.
Varicocele treatment
For appropriately selected men with clinically significant varicocele and relevant fertility problems.
Treatment of obstruction
When sperm production is present but sperm transport is blocked.
Treatment of sexual or ejaculation disorders
When intercourse or ejaculation is preventing natural conception.
Surgical sperm retrieval
For selected men with severe sperm-production problems or azoospermia.
Assisted reproductive techniques
Such as IVF or ICSI when appropriate for the couple.
The ESSM programme highlighted advances in the surgical treatment of male infertility and sperm retrieval techniques, while current European guidance provides more recent recommendations on diagnostic evaluation and treatment selection. (ESSM)
When Should a Man See a Fertility Specialist?
A man should consider a fertility evaluation when a couple has been unable to conceive after 12 months of regular, unprotected intercourse.
However, evaluation may be appropriate earlier when there is a known risk factor or previous reproductive problem.
This includes men with:
Azoospermia
Very low sperm count
Known varicocele
Previous testicular surgery
Testicular injury
Undescended testicles
Previous chemotherapy or radiation
Hormonal problems
Erectile dysfunction
Ejaculation problems
Previous fertility problems
Current EAU guidance recommends investigating both partners and evaluating men who seek medical help for fertility problems. (Uroweb)
Final Thoughts
There are many possible male infertility causes, and identifying the correct one is often more important than simply focusing on the semen analysis result.
Problems with sperm production, varicocele, azoospermia, hormonal disorders, genetic factors, metabolic health, sperm DNA integrity and sexual function can all play a role.
The good news is that many causes can be investigated, and some are potentially treatable.
A structured evaluation can help determine whether the problem is related to sperm production, sperm transport, hormones, sexual function or another medical condition—and can guide the most appropriate treatment for each individual.
If you and your partner are experiencing difficulty conceiving, a specialist male fertility assessment can help identify the cause and determine the next step.
Book an appointment with Professor Amr Raheem to discuss male fertility, sperm abnormalities, azoospermia, varicocele or other reproductive concerns.
References
European Society for Sexual Medicine (ESSM). 16th ESSM Congress Joint with the 12th EFS Congress – Final Programme, Istanbul, 29 January–1 February 2014. The programme includes dedicated sessions on male infertility, testosterone supplementation, obesity and metabolic syndrome, micro-TESE, varicocele surgery, surgical treatment of male infertility, idiopathic male infertility, and oxidative stress/sperm DNA damage. ESSM 2014 Congress Programme
European Association of Urology (EAU). EAU Guidelines on Sexual and Reproductive Health – Male Infertility. The current guideline covers the definition, causes, diagnostic work-up, semen analysis, hormonal assessment, genetic testing and treatment of male infertility. EAU Male Infertility Guidelines
European Association of Urology (EAU). EAU Guidelines on Sexual and Reproductive Health – Male Hypogonadism. Current recommendations caution against testosterone therapy for men seeking fertility. EAU Sexual and Reproductive Health Guidelines
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