Male Infertility: Causes and Evaluation

Male infertility refers to male-related factors that may reduce a couple’s chance of achieving pregnancy. It is not diagnosed from sperm count alone. A useful assessment combines reproductive and medical history, physical examination, semen analysis and, when indicated, hormonal, genetic or imaging tests. Because conception depends on both partners, fertility assessment is usually most informative when the male and female partner are evaluated in parallel rather than sequentially.

What does male infertility mean?

Infertility is generally defined as failure to achieve pregnancy after 12 months of regular, unprotected sexual intercourse. This definition applies to a couple, not to one partner in isolation.

A male factor may involve:

• reduced or absent sperm production;
• impaired sperm movement or morphology;
• obstruction preventing sperm from reaching the ejaculate;
• hormonal or genetic disorders;
• erectile or ejaculatory dysfunction that interferes with sperm deposition;
• previous surgery, infection, cancer treatment or testicular injury;
• medicines, exogenous testosterone or anabolic steroids that affect spermatogenesis.

Sometimes more than one factor is present. In other couples, no single cause fully explains the difficulty conceiving.

Does male infertility cause symptoms?

Often it does not. A man may have normal libido, erections and ejaculation yet still have abnormal semen parameters. Sexual performance therefore cannot be used as a substitute for fertility assessment.

Possible clues can include:

• a history of undescended testis;
• testicular asymmetry, reduced volume or a new lump;
• a clinically apparent varicocele;
• scrotal pain or heaviness;
• very low ejaculate volume or absent visible semen;
• erectile or ejaculatory difficulty;
• reduced sexual desire or other features suggesting hormonal disturbance;
• previous testicular torsion, trauma, infection or surgery;
• chemotherapy, radiotherapy or pelvic surgery;
• known genetic or endocrine disease.

None of these findings proves infertility on its own, and having no symptoms does not confirm normal fertility.

When should fertility assessment begin?

For most couples, evaluation is appropriate after 12 months of regular unprotected intercourse without conception. Earlier assessment may be reasonable when waiting could reduce options or when a known risk factor is present.

Examples include:

• advanced reproductive age or reduced ovarian reserve in the female partner;
• previous undescended testis, torsion or major testicular trauma;
• previous chemotherapy or radiotherapy;
• prior testicular, groin, prostate or pelvic surgery;
• previous vasectomy or suspected reproductive-tract obstruction;
• known endocrine or genetic disease;
• severe erectile or ejaculatory dysfunction;
• markedly small testes or a testicular mass;
• a previous abnormal semen analysis;
• current or previous use of testosterone or anabolic steroids;
• recurrent pregnancy loss or repeated assisted-reproduction failure where male evaluation is clinically relevant.

The timing should therefore reflect the couple’s combined reproductive circumstances rather than a rigid waiting period in every case.

What can cause male-factor infertility?

Male reproductive function depends on coordinated hormone signalling, testicular sperm production, open sperm-transport pathways and effective ejaculation. Problems can occur at any of these levels.

Reduced sperm production

Spermatogenesis may be affected by:

• varicocele;
• undescended testis;
• testicular infection, torsion or trauma;
• chemotherapy or radiotherapy;
• some genetic conditions;
• endocrine disorders;
• severe systemic illness;
• certain medicines or toxins;
• exogenous testosterone or anabolic steroids;
• smoking, heavy alcohol use and other substance exposure;
• marked obesity or major nutritional problems.

The presence of a risk factor does not tell us the degree of fertility impairment. The clinical effect varies substantially between individuals.

Obstruction or sperm-transport problems

Sperm may be produced in the testes but fail to appear in the ejaculate because of congenital or acquired obstruction. Causes can include congenital absence of the vas deferens, previous infection, surgery, vasectomy or ejaculatory-duct obstruction.

Azoospermia — no sperm detected in the ejaculate — therefore does not automatically mean that the testes make no sperm. Obstructive and non-obstructive causes need to be distinguished.

Hormonal causes

The hypothalamus, pituitary gland and testes form the hormonal axis that supports sperm production. Disorders affecting this axis can reduce spermatogenesis.

One particularly important issue is testosterone taken from outside the body. Testosterone treatment can suppress the hormonal signals required for sperm production and may markedly reduce sperm concentration, sometimes to the point that no sperm are seen in semen.

Men who are trying to conceive should disclose testosterone, anabolic-steroid and hormone use during assessment. Prescription treatment should not be stopped or changed without medical advice.

Erectile and ejaculatory problems

Even with adequate sperm production, conception may be reduced if erection or ejaculation problems prevent semen from being deposited in the vagina. Retrograde ejaculation, anejaculation, some neurological disorders and previous pelvic operations can be relevant.

See also erectile dysfunction when erection quality is part of the fertility problem.

What is included in the first assessment?

The purpose of the first assessment is not to order every available test. It is to identify the most plausible clinical questions and select investigations that can answer them.

History may cover:

• duration of attempts to conceive;
• previous pregnancies with the current or previous partners;
• timing and frequency of intercourse;
• childhood testicular development and previous groin surgery;
• puberty and sexual development;
• testicular infection, torsion or trauma;
• erections, ejaculation and libido;
• recent febrile illness;
• chronic disease and previous operations;
• current medicines and supplements;
• testosterone or anabolic-steroid exposure;
• chemotherapy or radiotherapy;
• smoking, alcohol and recreational substances;
• occupational heat, chemical or radiation exposure;
• family history of infertility or genetic disease.

What does the physical examination look for?

Where appropriate, the examination may assess:

• secondary sexual characteristics;
• testicular position, approximate size and consistency;
• the epididymis and presence of the vas deferens;
• clinically detectable varicocele;
• penile or urethral abnormalities relevant to fertility;
• breast enlargement or other signs suggesting endocrine disturbance;
• a testicular mass or focal tenderness.

Examination findings do not measure fertility directly. They are interpreted alongside semen and laboratory results.

What does semen analysis show?

Semen analysis is a core investigation in male infertility. It may assess:

• semen volume;
• sperm concentration;
• total sperm number;
• progressive and non-progressive motility;
• morphology;
• vitality in selected samples;
• other semen characteristics and cells where relevant.

The WHO reference distributions are not a fertile-versus-infertile dividing line. A result below a reference value does not mean natural conception is impossible, and a result within the reference range does not mean conception will occur.

Interpretation should consider the whole semen profile, the quality of sample collection and the reproductive characteristics of both partners.

How should a semen sample be collected?

Follow the laboratory’s instructions rather than relying on a generic internet rule. Requirements can differ between laboratories.

Common principles include:

• collect the entire ejaculate in the approved container;
• tell the laboratory if part of the sample was lost;
• do not use ordinary condoms, lubricants or unsuitable containers unless the laboratory specifically provides an approved alternative;
• follow the requested abstinence interval;
• follow transport-time and temperature instructions if the sample is produced away from the laboratory;
• report recent fever, major illness, medicines and hormone use.

Poor collection or transport can make a result difficult to interpret.

Is one semen analysis enough?

Not always. Semen parameters vary between samples in the same person.

Current EAU guidance states that if semen analysis is normal according to WHO criteria, one test may be sufficient in the diagnostic work-up. If the baseline analysis is abnormal, at least two consecutive semen analyses are recommended before drawing conclusions and planning further andrological investigation.

The repeat interval depends on the clinical context rather than a universal timetable.

Does everyone need hormone testing?

No. Hormone testing should answer a clinical question. It becomes particularly relevant with severe oligozoospermia or azoospermia, small testes, reduced libido, signs of hypogonadism or another endocrine concern.

Depending on the situation, tests can include follicle-stimulating hormone, luteinising hormone and total testosterone, with additional endocrine tests selected according to the findings.

Hormonal testing should not be interpreted independently from semen results and examination.

When are ultrasound and other imaging useful?

Imaging is not a substitute for history, examination and semen analysis. Scrotal ultrasound may be useful when the physical examination is unclear, when a mass is suspected, when testicular structure or volume needs assessment, or in selected cases of obstruction.

Transrectal ultrasound may be considered in specific men with low semen volume and a pattern suggesting distal seminal-tract obstruction. Routine imaging of every infertile man is not required.

When may genetic testing be needed?

Genetic investigation is most relevant in selected men with azoospermia, severe oligozoospermia, congenital absence of the vas deferens or clinical features suggesting a chromosomal or monogenic condition.

Testing may include karyotype analysis, Y-chromosome microdeletion testing or CFTR-related evaluation depending on the phenotype and semen findings. Genetic counselling is important when a result can affect the patient, partner, treatment strategy or future offspring.

Is sperm DNA fragmentation a routine test?

No. Sperm DNA fragmentation testing is not required for every fertility assessment.

EAU guidance supports its use in selected situations such as recurrent pregnancy loss, unexplained infertility or repeated failure of assisted reproductive treatment. The result still needs clinical interpretation; a high value does not identify one specific cause or dictate a single treatment.

How is treatment planned?

Treatment depends on the cause and the couple’s reproductive situation. Options may include:

• addressing reversible medical or lifestyle factors;
• treating a clinically relevant varicocele in appropriately selected men;
• correcting a defined obstruction when suitable;
• endocrine treatment for specific hormonal disorders;
• treatment of erectile or ejaculatory dysfunction;
• surgical sperm retrieval in selected azoospermia cases;
• assisted reproductive techniques when appropriate.

The aim is not merely to make one semen number look better. The relevant endpoint is the couple’s reproductive goal, balanced against time, age, ovarian reserve, underlying diagnosis and treatment burden.

Do supplements and antioxidants improve fertility?

Evidence for empirical antioxidants and fertility supplements remains inconsistent. Different products combine different compounds and doses, and improvement in a laboratory parameter does not necessarily translate into improved live-birth outcomes.

A supplement should not replace evaluation for a correctable condition such as varicocele, endocrine disease, obstruction or gonadotoxic medication exposure. Product-specific risks and interactions also matter.

Does male infertility mean sexual dysfunction?

No. Fertility, erection quality, ejaculation, libido and orgasm are related aspects of reproductive and sexual health but are not interchangeable.

A man can have abnormal semen results with otherwise normal sexual function. Conversely, a man can have erectile or ejaculatory dysfunction despite normal sperm production.

When should assessment not be delayed?

Prompt urological assessment is appropriate for a new testicular mass, marked testicular asymmetry, severe or persistent testicular pain, absent palpable testes, known gonadotoxic exposure, azoospermia or very severe semen abnormalities, or a combination of infertility with significant endocrine symptoms.

Sudden severe testicular pain is an emergency symptom and should not wait for a routine fertility appointment.

Medical information note

Male infertility assessment is individual and couple-based. Semen reference values, hormone levels and imaging findings do not independently establish whether natural conception will or will not occur.