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fertility

Male Infertility: Causes of Low Sperm Count and Treatment Options

Male-factor issues contribute to roughly half of all infertility cases. The most common problems involve sperm count, motility, and morphology. A semen analysis is the central non-invasive diagnostic test; evaluating both partners early avoids unnecessary delay, and many causes are treatable.

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What does a semen analysis measure?

A semen analysis is the first and most important test in evaluating male fertility 1. It typically measures:

  • Sperm concentration: The number of sperm per milliliter of semen
  • Total sperm count: Concentration multiplied by ejaculate volume
  • Motility: The percentage of sperm that are moving, and whether they move progressively (forward) or in place
  • Morphology: The percentage of sperm with a normal shape under a standardized classification system (Kruger strict criteria)
  • Ejaculate volume and pH

A single abnormal result should be confirmed with a repeat test 2–4 weeks later, because sperm parameters can vary significantly from sample to sample. World Health Organization reference values (most recently updated in 2021) serve as the standard for interpretation, and your clinician will interpret results in the full clinical context 1.

What are the most common causes of low sperm count?

Varicocele: An abnormal enlargement of the veins that drain the testicle. Varicoceles are found in roughly 35–40% of men presenting for infertility evaluation and are the most commonly identified correctable cause 1. Impaired venous drainage raises scrotal temperature, which is thought to impair sperm production.

Hormonal imbalances: Testosterone, FSH, and LH work together to drive sperm production. Conditions affecting the pituitary gland or hypothalamus can disrupt this axis. Notably, exogenous testosterone (testosterone replacement therapy) suppresses the pituitary signals needed for sperm production and can markedly reduce sperm count — this is an important point for men who have used testosterone supplements 1.

Obstruction: Some men produce normal sperm but have a blockage preventing them from reaching the ejaculate. Prior vasectomy is an obvious cause; infections (including prior chlamydia or gonorrhea) and congenital bilateral absence of the vas deferens (associated with CFTR gene mutations / cystic fibrosis carrier status) are others.

Genetic causes: Y-chromosome microdeletions and Klinefelter syndrome (47,XXY) are among the genetic conditions that impair sperm production. Genetic testing is often recommended when sperm counts are very low or absent 1.

Prior chemotherapy or radiation: Certain cancer treatments have dose-dependent effects on sperm production, which may be temporary or permanent. Sperm banking before treatment is important for men who wish to preserve fertility.

Lifestyle and environmental factors: Elevated scrotal temperature, tobacco use, heavy alcohol use, anabolic steroid use, and exposure to certain pesticides or occupational chemicals have been associated with reduced sperm parameters, though the strength of evidence varies.

Unexplained (idiopathic): In many cases, no specific cause is identified even after a thorough evaluation.

What other tests are done as part of a male infertility evaluation?

Depending on the semen analysis results, a urologist specializing in male infertility may recommend 12:

  • Hormone panel: FSH, LH, testosterone, prolactin — identifies hormonal causes
  • Genetic testing: Karyotype and Y-chromosome microdeletion analysis when sperm count is very low or absent
  • Scrotal ultrasound: Detects varicoceles and evaluates testicular structure
  • Urinalysis post-ejaculation: Rules out retrograde ejaculation (sperm going backward into the bladder)
  • Sperm DNA fragmentation testing: Increasingly used, particularly when IVF with ICSI has had poor outcomes or when conventional parameters are borderline; clinical application continues to evolve 2

What are the treatment options?

Treatment depends on the cause and the severity of the abnormality:

Varicocele repair: Surgical or minimally invasive correction of a clinically palpable varicocele can improve sperm parameters in some men. Current AUA/ASRM guidance recommends considering varicocelectomy for men with a palpable varicocele, infertility, and abnormal semen parameters when the female partner has normal fertility or a treatable cause 1.

Hormonal treatment: When a hormonal axis problem is identified (such as hypogonadotropic hypogonadism), specific hormone therapy can restore sperm production — this is distinct from testosterone replacement, which suppresses production 1.

Surgical sperm retrieval: For men with obstructive azoospermia (normal production but blocked delivery), sperm can be retrieved directly from the epididymis or testicle and used for IVF with intracytoplasmic sperm injection (ICSI). ICSI involves injecting a single sperm directly into an egg and is effective even with very low sperm numbers or poor motility 2.

Intrauterine insemination (IUI): For mild male-factor abnormalities, processing and concentrating a semen sample before IUI can increase the number of motile sperm reaching the egg.

In vitro fertilization with ICSI: For moderate-to-severe male factor, IVF with ICSI is the most effective assisted reproductive option 2.

Donor sperm: If sperm cannot be obtained or if other paths are not feasible or desired, donor sperm from an accredited sperm bank is a well-established option.

Common questions

Can lifestyle changes improve sperm count?

For men with lifestyle-related factors — tobacco use, heavy alcohol intake, anabolic steroids, or excessive heat exposure — modifying these habits is reasonable and worthwhile. However, the magnitude of improvement and how long it takes to see change can vary. Spermatogenesis (the full cycle of sperm production) takes roughly 70-80 days, so meaningful change in semen analysis results takes at least 3 months after any intervention.

Does taking testosterone supplements affect fertility?

Yes, significantly. Testosterone replacement therapy suppresses the pituitary signals (LH and FSH) that drive sperm production. Men who have used testosterone supplements may have markedly reduced sperm counts. Recovery after stopping testosterone can take months to over a year. This is a critical point to discuss with your clinician before or during fertility evaluation.

What is azoospermia and can it be treated?

Azoospermia means no sperm are found in the ejaculate. It can be obstructive (sperm are produced but cannot reach the ejaculate) or non-obstructive (production is severely impaired). For obstructive azoospermia, surgical sperm retrieval with IVF/ICSI is often successful. For non-obstructive azoospermia, sperm retrieval is attempted but success rates are lower and depend on the cause — genetic evaluation is important.

Which specialist evaluates male infertility?

A urologist with subspecialty training in male reproductive medicine (sometimes called a reproductive urologist or andrologist) evaluates and treats male-factor infertility. This evaluation often happens in parallel with the female partner's evaluation by a reproductive endocrinologist.

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Important notes

  • —Pain, swelling, or a lump in the testicle should prompt evaluation by a urologist promptly — these symptoms can indicate conditions unrelated to infertility that require separate attention
  • —Men considering surgical varicocele repair should discuss realistic expectations with their urologist — not all men see significant improvement in sperm parameters after repair

Sudden severe testicular pain can be a sign of testicular torsion, which is a surgical emergency. Call 911 or go to the nearest emergency room immediately.

This article provides general education about male infertility. A urologist specializing in male reproductive medicine is the appropriate specialist for evaluation and treatment. Gale can help you prepare questions and understand next steps.

References

  1. 1.Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ, Mulhall JP, Niederberger C, Sandlow JI, Sokol RZ, Spandorfer SD, Tanrikut C, Treadwell JR, Oristaglio JT, Zini A (2021). Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline Part I. Journal of Urology. doi:10.1097/JU.0000000000001521 ✓Primary guideline source for semen analysis interpretation, causes of male infertility (varicocele, hormonal, genetic, obstruction, exogenous testosterone), and evidence-based treatment indications including varicocele repair and hormonal therapy
  2. 2.Schlegel PN, Sigman M, Collura B, et al. (2021). Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline Part II. Journal of Urology. doi:10.1097/JU.0000000000001520 ✓Guideline source for sperm retrieval techniques, ICSI for azoospermia, sperm DNA fragmentation testing indications, and assisted reproductive technology choices for male-factor infertility

2 sources, numbered by first appearance. General health information, not medical advice — synthetic demonstration content.