Male Infertility: Semen Analysis, Sperm DNA Fragmentation, and What Can Be Done

When a couple has difficulty conceiving, most people think first about the woman's health. But the male partner is involved in many cases. Estimates suggest a male factor is present in about half of couples with infertility, either as the only cause or alongside a female factor [1][2]. Male fertility is often misunderstood. Some men assume that one normal semen report means everything is fine. Others get one abnormal result and conclude they can never father a child. Neither conclusion is safe. This article explains, in plain language, what a semen test shows, when an advanced test called sperm DNA fragmentation is useful, what causes male infertility, and what treatments exist. It also points out where the evidence is weak or where expert groups disagree.

What is infertility?

The World Health Organization (WHO) defines infertility as not achieving a pregnancy after 12 months or more of regular unprotected sex. It describes infertility as a disease of the male or female reproductive system. WHO estimates that about 1 in 6 adults worldwide experience infertility at some point in life [3]. The figure is similar in rich and poor countries. WHO also highlights stigma and cost as major barriers to care [3].

The basic test: semen analysis

A semen analysis (sometimes called a sperm test) is the first test of male fertility. A laboratory examines a semen sample for how much semen there is and how many sperm it contains, how they move, and what they look like. To get a reliable result, the WHO laboratory manual recommends collecting the sample after 2 to 7 days without ejaculation [4]. Follow your laboratory's instructions on collection and delivery of the sample.

The main measurements

1. Sperm concentration (sperm count). This is how many sperm there are per millilitre (mL) of semen.

• Oligozoospermia means a lower-than-expected count.
• Azoospermia means no sperm are found in the ejaculate.

1. Sperm motility (movement). Sperm need to swim forward to reach the egg. Progressive motility means moving in straight lines or large circles. Asthenozoospermia means reduced motility.
2. Sperm morphology (shape). Under a high-power microscope, a normal sperm has an oval head, an intact midpiece and a single tail. Teratozoospermia means a high proportion of abnormally shaped sperm. Morphology is judged by strict criteria, so only about 4% of sperm in a fertile man's sample may look "normal" [4][5].

Other measurements

• Volume. The semen volume is also measured. A low volume can point to a blockage, to semen flowing backwards into the bladder (retrograde ejaculation), or to a hormonal problem.
• pH. Semen is slightly alkaline, with a pH of about 7.2 or above [4].
• White blood cells. More than 1 million per mL is called leukocytospermia and can suggest inflammation or infection that needs medical review [4].

What the numbers mean

The 6th edition of the WHO manual (2021) gives these lower reference points (the 5th percentile in men whose partners conceived naturally within 12 months) [5]: Measurement Lower reference value Semen volume 1.4 mL Sperm concentration 16 million per mL Total sperm number 39 million per ejaculate Total motility 42% Progressive motility 30% Normal forms 4% The 5th edition (2010) gave a concentration of 15 million per mL, and some reports and websites still quote the older figure [5]. Four points matter in practice:

1. These are guides, not pass-or-fail lines. The 6th edition moved away from rigid "normal" cut-offs towards "decision limits" and treats results as a continuum [6]. A man above the limits is not guaranteed to conceive, and a man slightly below them is not necessarily infertile.
2. One result is not a diagnosis. Illness, fever, stress, medication changes, and the abstinence period can all change a result. The AUA/ASRM guideline recommends at least two semen analyses, a few weeks apart, before drawing conclusions [2][7].
3. A normal report does not guarantee fertility. Semen analysis is an imperfect predictor of whether a pregnancy will happen [8].
4. Results should be read by an experienced doctor, in the context of the man's history, examination and his partner's evaluation.

Advanced testing: sperm DNA fragmentation

A standard semen analysis counts sperm, checks their movement and looks at their shape. It cannot show what is inside the sperm head, where the paternal DNA is stored. Sperm DNA fragmentation (SDF) means breaks in that DNA. Egg cells can repair minor damage after fertilisation, but when damage is extensive it may exceed the egg's repair capacity. High levels have been linked to lower fertilisation rates, poorer embryo development, failed implantation and miscarriage, although the evidence behind the recommendations is of moderate to low quality [9].

How it is measured

Results are reported as a DNA fragmentation index (DFI), the percentage of sperm with damaged DNA. Laboratories use several methods:

• TUNEL uses fluorescent tags to detect broken DNA ends.
• SCSA (sperm chromatin structure assay) uses a dye and flow cytometry to detect DNA that is more easily damaged.
• SCD (sperm chromatin dispersion test) looks for a "halo" of DNA loops around the sperm head. Intact DNA forms a large halo, and damaged DNA forms a small one or none.

Cut-offs differ between assays and laboratories, so a DFI figure should be interpreted using the reference limits of the laboratory that produced it, rather than a universal threshold [9]. A result is best discussed with your fertility specialist.

What causes sperm DNA damage

Oxidative stress is an important cause. This is an imbalance in which harmful molecules called reactive oxygen species outweigh the body's natural antioxidant defences. Other mechanisms also play a role. Factors linked to higher DNA fragmentation include:

• Medical: varicocele, genital tract infections, increasing paternal age, uncontrolled diabetes, autoimmune conditions and recent fever.
• Lifestyle and environment: tobacco smoking and vaping, obesity, heat from work or habits (for example, bakeries and heavy machinery), and exposure to heavy metals, pesticides or radiation.

Who should have the test?

Expert bodies do not recommend SDF testing as a routine first test in every infertile couple. The AUA, EAU and ASRM acknowledge the importance of DNA damage but advise against routine use [10]. One reason is that, for most men, no proven treatment improves DNA integrity, so the result may not change management [10]. Some specialist groups support testing in selected situations, including recurrent miscarriage, unexplained infertility, repeated failure of IUI or IVF, and when assessing a varicocele [9][11]. The 2024 AUA/ASRM amendment also recognises SDF testing in certain settings and adds testicular sperm as an option for men with high DNA fragmentation [7]. Positions differ between organisations, so the decision should be individual.

Causes of male infertility

Doctors usually group causes by where in the body the problem arises.

Pre-testicular (hormonal) causes

The brain controls sperm production through hormones. The hypothalamus releases GnRH, which prompts the pituitary gland to release FSH and LH, and these signal the testes to make sperm and testosterone. If FSH and LH are low (hypogonadotropic hypogonadism), the testes do not get the signal. Causes include genetic conditions such as Kallmann syndrome, pituitary tumours, and external hormones such as anabolic steroids or testosterone replacement.

Testicular causes

Here the signals are normal, but the testes cannot produce enough healthy sperm.

• Varicocele. This is an enlargement of veins in the scrotum. It is found in about 15% of men in general and about 35% of men with primary infertility (up to 80% in secondary infertility, though age may contribute) [12]. Many men with a varicocele father children without difficulty [13].
• Genetic causes such as Klinefelter syndrome (47,XXY) or Y-chromosome microdeletions.
• Undescended testes in childhood (cryptorchidism).
• Injury or infection, including mumps involving the testes after puberty.

Post-testicular causes

Sperm are made normally but cannot leave the body.

• Obstruction of the epididymis or vas deferens, from past infection, surgery or birth differences. One example is congenital bilateral absence of the vas deferens (CBAVD), strongly linked to CFTR gene variants. The female partner should be offered CFTR testing [2].
• Ejaculation problems, including retrograde ejaculation and nerve damage from diabetes or other conditions.

No clear cause

In many men with abnormal semen, no cause is found even after thorough evaluation. This is called idiopathic infertility.

Treatment options

Treatment depends on the cause.

Lifestyle changes

For milder problems, reducing heat exposure (long hot baths, saunas, working with a laptop directly on the lap), stopping tobacco, and managing weight are sensible first steps. WHO's expert advisers looked specifically at obesity, heat and tobacco as lifestyle factors that may affect fertility [14]. The strength of evidence differs for each, so lifestyle changes should be seen as supportive rather than a guaranteed fix.

Antioxidant supplements: uncertain evidence

Antioxidant supplements such as coenzyme Q10, vitamins C and E, zinc and L-carnitine are widely used. The evidence is weak. The 2022 Cochrane review found that antioxidants may increase live birth, but certainty was very low, and when studies at high risk of bias were excluded, no increase in live birth was found [15]. There was no evidence of a higher miscarriage risk, but supplements may cause mild stomach upset [15]. A recent comparison of guidelines notes that WHO takes a neutral position on antioxidant therapy [16]. Supplements should be taken under medical advice, not self-prescribed in high doses.

Medicines

• Hormone treatment. In selected men with hypogonadotropic hypogonadism, injectable gonadotropins (hCG, hMG) or clomiphene citrate (used off-label in men) can stimulate sperm production under specialist supervision.
• Antibiotics may be used if infection is confirmed in semen.
• Testosterone must not be used to treat male infertility. External testosterone suppresses the body's own hormones and can stop sperm production. The AUA guidance advises that men who want current or future fertility should not be prescribed testosterone [7].

Surgery: varicocele repair is debated

This is an area where guidelines disagree:

• For repair: the 2024 AUA/ASRM guideline says to consider surgery when a varicocele is palpable, semen parameters are abnormal and the couple is trying to conceive [17]. The Global Andrology Forum treats a clinical varicocele with abnormal sperm parameters as the clearest indication for repair [18].
• Against routine repair: UK guidance (NICE) advises against offering varicocele surgery solely as fertility treatment, because it has not been shown to improve pregnancy rates [13].

Improvement in semen numbers after surgery is not the same as a higher chance of a baby, which is why individual assessment by a urologist or andrologist is important. Microsurgery can also be used to reopen some blockages, for example by reconnecting the vas deferens (vasovasostomy).

Assisted reproduction

• IUI (intrauterine insemination). Sperm are processed in the laboratory and placed in the uterus around ovulation. It generally needs a reasonable number of motile sperm after processing, and your fertility team will advise whether it is suitable.
• IVF with ICSI (intracytoplasmic sperm injection). An embryologist injects a single sperm into an egg. ICSI is the standard approach for severe male factor infertility, such as very low counts, very poor motility, or in some cases high DNA fragmentation. It is not needed for every couple.
• Surgical sperm retrieval (TESA, micro-TESE). When no sperm reach the ejaculate (azoospermia), sperm may be retrieved directly from testicular tissue for ICSI. For men with high sperm DNA fragmentation, the AUA/ASRM amendment lists testicular sperm as an option [7].
• Genetic testing. Y-chromosome microdeletion testing is now advised mainly when sperm concentration is below 1 million per mL [19].

What this means for couples in India

• Both partners should be tested from the start. A semen analysis is simple, painless and inexpensive compared with the tests and treatments a woman may otherwise undergo first.
• Stigma is a real barrier. WHO notes that stigma and cost limit access to care worldwide [3]. A semen test is a health check, not a judgement on a man's masculinity.
• Choose a regulated centre. Assisted reproduction clinics in India are regulated under the Assisted Reproductive Technology (Regulation) Act, 2021 [20].
• Be cautious about quick fixes. Ask what a test or treatment is for, what evidence supports it, and what it will cost.

When to see a doctor

• After 12 months of trying, or after about 6 months if the woman is over 35, which many specialists advise [7][21]. Do not wait if there is a known risk factor.
• Sooner, if you have had testicular surgery or injury, undescended testes, genital infection, cancer treatment, or problems with erections or ejaculation.
• If a semen report is abnormal, which should be repeated and followed by a visit to a urologist or andrologist.

A fertility assessment can also reveal broader health problems, so it is worth taking seriously [1].

The bottom line

Fertility should be assessed in both partners from the start. A basic semen analysis gives a useful first picture. Advanced tests such as sperm DNA fragmentation can help in selected cases but are not routine, and some treatments, including antioxidant supplements and varicocele surgery, have uncertain or contested evidence. With treatments ranging from lifestyle changes and medication to microsurgery and ICSI, many couples can be helped. Early, honest evaluation of both partners is the best first step.

References

1. Ferlin A, Calogero A, et al. Management of male factor infertility: position statement from the Italian Society of Andrology and Sexual Medicine (SIAMS). J Endocrinol Invest. https://research.unipd.it/handle/11577/3444077
2. American Urological Association / American Society for Reproductive Medicine. Diagnosis and treatment of infertility in men: AUA/ASRM guideline (2020; amended 2024). Summary: Yale Medicine Urology. Male infertility guideline amendments released. https://medicine.yale.edu/lab/urology-mens-health-blog/2025/may/
3. World Health Organization. 1 in 6 people globally affected by infertility. 4 April 2023. https://www.who.int/news/item/04-04-2023-1-in-6-people-globally-affected-by-infertility
4. Changes in reference values from the 2nd to the 6th edition of the WHO laboratory manual for the examination and processing of human semen. Fertil Steril. 2022;117(2):237–245. https://pmc.ncbi.nlm.nih.gov/articles/PMC8842884/table/tbl2
5. The sixth edition of the WHO manual for human semen analysis: a critical review and SWOT analysis. Life (Basel). 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8706130/
6. Key updates from the AUA/ASRM male infertility guideline amendment (2024). Urology Times. https://www.urologytimes.com/view/key-updates-from-the-aua-asrm-male-infertility-guideline-amendment
7. Review of semen analysis in the evaluation of male infertility. University of Modena and Reggio Emilia. https://iris.unimo.it/handle/11380/1395390
8. Esteves SC, et al. Sperm DNA fragmentation testing: summary evidence and clinical practice recommendations. Andrologia. 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7988559/
9. Pros and cons of sperm DNA fragmentation testing: weighing the evidence. https://pmc.ncbi.nlm.nih.gov/articles/PMC5643715
10. Agarwal A, et al. Clinical utility of sperm DNA fragmentation testing: concise practice recommendations. Transl Androl Urol. 2017. https://tau.amegroups.org/article/view/16084/17039
11. Epidemiology of varicocele. https://pmc.ncbi.nlm.nih.gov/articles/PMC4770482
12. NICE and Royal College of Surgeons guidance on varicocele, as summarised by iatroX. https://iatrox.com/shared/68a18f3601224181e7ac4da2/what-are-the-current-guidelines-for-the-management-of-varicocele-in-patient-ac4da2
13. The diagnosis of male infertility: an analysis of the evidence to support the development of global WHO guidance. University of Dundee. https://discovery.dundee.ac.uk/en/publications/the-diagnosis-of-male-infertility-an-analysis-of-the-evidence-to-/
14. de Ligny W, Smits RM, Mackenzie-Proctor R, et al. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2022;5:CD007411. https://pubmed.ncbi.nlm.nih.gov/35506389/
15. Male infertility in the 2025 WHO infertility guideline: a comparative analysis with AUA/ASRM, EAU, ESHRE and NICE recommendations. Andrology. 2026. https://www.urotoday.com/recent-abstracts/men-s-health/male-infertility/171409-male-infertility-in-the-2025-who-infertility-guideline-a-comparative-analysis-with-aua-asrm-eau-eshre-and-nice-recommendations.html
16. Black Health. Male infertility in Black men (summarising the 2024 AUA/ASRM guideline). https://www.blackhealth.org/articles/male-infertility-black-men/
17. Çayan S, et al. Global Andrology Forum clinical guidelines on the management of infertile men with varicocele. World J Mens Health. 2025. https://avesis.iuc.edu.tr/yayin/024eadfb-7a22-4fe6-a0c4-8c2883e4193f/global-andrology-forum-gaf-clinical-guidelines-on-the-management-of-infertile-men-with-varicocele
18. InVia Fertility Specialists. Diagnostic male infertility test. https://www.inviafertility.com/blog/blog/invia-fertility-specialists/pattypaganucci/diagnostic-male-infertility-test/