Most men with fertility problems have no obvious symptoms at all. Unlike many health conditions that announce themselves with pain or visible changes, male infertility is usually discovered only after a couple has been trying to conceive without success, typically for a year or longer. That said, there are physical signs, lifestyle risk factors, and medical tests that can reveal whether a fertility problem exists.
Physical Signs That May Point to a Problem
Male infertility rarely comes with a clear warning sign, but a few physical changes are worth paying attention to. The most common structural issue is a varicocele, which is an enlargement of veins inside the scrotum. Varicoceles contribute to roughly 40% of all male infertility cases. Larger ones can feel like a soft lump or a “bag of worms” above the testicle, and they sometimes cause a dull ache that improves when you lie down. Smaller varicoceles may produce no sensation at all and can only be detected through an ultrasound.
Testicle size matters too. Noticeably small or shrinking testicles (called testicular atrophy) can signal low testosterone or problems with sperm production. Low testosterone itself brings a cluster of changes: reduced sex drive, loss of muscle mass, fatigue, and sometimes depression. Difficulty getting or maintaining erections can also be part of the picture, though erectile dysfunction alone doesn’t necessarily mean infertility.
Other physical red flags include testicles that never fully descended during childhood, pain or swelling in the scrotum, and breast tissue growth, which can indicate a hormonal imbalance.
Lifestyle Factors That Hurt Sperm Quality
Your daily habits have a measurable impact on sperm. A recent cross-sectional study comparing men with normal versus abnormal body weight found striking differences: men with a higher BMI had an average sperm concentration of about 70 million per milliliter, compared to 95 million in men at a healthy weight. Their motility (the percentage of sperm that actually swim) dropped from 78% to 61%, and their sperm DNA showed significantly more damage.
Smoking is another major factor. Tobacco use was linked to a 2.36-fold increase in the risk of impaired semen quality. Chewing tobacco was even worse, raising the risk by 4.22 times. Heat exposure also plays a role. Men who work in high-heat environments (welders, bakers, long-haul drivers) had elevated sperm DNA damage at notably higher rates, with about 62% of heat-exposed men showing damage compared to 47% of those without regular exposure. Frequent hot tub use and laptops placed directly on the lap fall into the same category.
What Happens During a Fertility Evaluation
The American Urological Association and the American Society for Reproductive Medicine recommend that both partners be evaluated at the same time when a couple is struggling to conceive. For men, the process starts with a reproductive history and a semen analysis, which is the single most informative test for male fertility.
A semen analysis is done in a lab, not at home. You provide a sample (usually through masturbation at a clinic or at home with a quick transport to the lab), and technicians evaluate it both under a microscope and by computer. They measure several things:
- Sperm concentration: how many sperm are present per milliliter
- Total sperm count: at least 39 million per ejaculate is considered the lower threshold of normal
- Motility: at least 42% of sperm should be moving
- Morphology: at least 4% of sperm should have a normal size and shape
- Volume and pH: the amount and acidity of the semen itself
If one or more of these numbers comes back abnormal, the test is usually repeated, since sperm production fluctuates. Consistently abnormal results lead to further workup with a male reproductive specialist.
Blood Tests and Hormones
When semen analysis results are abnormal, blood work helps identify the underlying cause. The key hormones tested are follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. FSH is particularly telling because it drives sperm production. Normal adult FSH falls between 1.5 and 12.4 mIU/mL. A high FSH level suggests the testicles aren’t responding properly to the brain’s signal to make sperm. A low FSH, on the other hand, can mean the brain isn’t sending the signal in the first place, which is a different (and often more treatable) problem.
Hormonal disorders account for roughly 2% to 5% of male infertility cases. They’re a small slice of the overall picture, but they’re important to identify because they’re among the most correctable causes.
Imaging and Advanced Tests
Ultrasound is the go-to imaging tool. A scrotal ultrasound can confirm varicoceles, measure testicular volume, detect tumors, identify undescended testicles, and spot abnormalities in the epididymis (the coiled tube where sperm mature). When a man has no sperm in his semen at all, a condition called azoospermia, a transrectal ultrasound can check for blockages in the ejaculatory ducts, absent vas deferens, or cysts that might be physically preventing sperm from reaching the ejaculate.
In some cases, genetic testing is also recommended. Conditions like Klinefelter syndrome (an extra X chromosome) and Y chromosome microdeletions are well-established genetic causes of very low or absent sperm production. Men with cystic fibrosis gene mutations may be born without the vas deferens entirely, making natural conception impossible without medical intervention.
Why At-Home Sperm Tests Fall Short
Home sperm test kits are widely available and can give you a rough estimate of sperm concentration. But they capture only a fraction of what a lab analysis reports. They generally can’t measure motility, morphology, DNA integrity, or semen volume with any precision. A home test might tell you your count looks “normal” while missing the fact that very few of those sperm are moving or shaped correctly. Even with a normal-looking result, you could still be dealing with a fertility issue the kit simply can’t detect. These tests are reasonable as a first gut check, but they don’t replace a formal semen analysis.
How Male Infertility Breaks Down by Cause
The largest category of male infertility, accounting for 65% to 80% of cases, involves primary testicular problems where sperm parameters are abnormal but no single clear cause is identified. Transport disorders, like a prior vasectomy or blocked ducts, make up about 5%. Hormonal issues account for 2% to 5%. And in 10% to 20% of cases, men have completely normal semen results but still can’t conceive, which is classified as unexplained.
From a treatment standpoint, only about 18% of male infertility cases have a directly correctable cause, such as a blockage that can be surgically opened, a hormonal deficiency that responds to medication, or a varicocele that improves after repair. About 70% of cases involve sperm quality problems that can’t be fully reversed but can often be worked around with assisted reproduction techniques. The remaining 12% involve complete and permanent sterility.
The takeaway is that there’s no single symptom or home observation that reliably tells you whether a man is infertile. The only definitive way to know is through a semen analysis, and if that’s abnormal, through the follow-up tests that pinpoint the reason. If you’ve been trying to conceive for 12 months without success, both partners should be evaluated simultaneously rather than assuming the issue lies with one person.