A varicocele diagnosis usually arrives with a reassurance and very little else. Most men are told it is common, that it rarely needs treatment, and to come back if it hurts. Almost nobody is told to check what it is doing to their sperm.
That gap matters. Varicocele is one of the most frequently identified findings in men investigated for infertility, and the only way to know whether yours is affecting yours is to measure it.
What a varicocele does to sperm production
The veins around each testicle, the pampiniform plexus, work as a heat exchanger. They keep the testicles a few degrees below core body temperature, which is the range sperm production needs. When those veins enlarge and blood pools, that cooling system works less well. Our guide to testicle temperature and heat damage covers why that matters.
Raised scrotal temperature and oxidative stress are the two mechanisms most often described. Both act on sperm production over months rather than days, which is why the effect is gradual and easy to miss.
Varicoceles are common. NHS patient information from Liverpool University Hospitals describes them as a collection of enlarged veins that usually causes no symptoms at all, with treatment not needed in most cases.
Most men with a varicocele are fertile
This is the part that gets lost. A varicocele does not mean you have a fertility problem. The same NHS leaflet makes the point directly: most men with varicoceles are not infertile. What changes is the likelihood, not the outcome.
The largest population dataset on this is a study of 7,035 young men across six European countries, published in European Urology in 2016. Unlike most varicocele research, it looked at men from the general population rather than men already attending fertility clinics. It found varicocele associated with poorer semen quality and altered reproductive hormone levels, and the association held even in men with the mildest form, grade 1.
That is a population-level association. It does not tell you your individual result, and the visible size of a varicocele is a poor guide to what any one man's numbers will look like.
So a diagnosis is a reason to test, not a reason to assume.
What a sperm test measures
A semen analysis reports several parameters. The WHO laboratory manual for the examination and processing of human semen, sixth edition (2021) sets the current reference values:
| Parameter | WHO 6th edition lower reference limit |
|---|---|
| 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 morphology | 4% |
These limits come from men whose partners conceived within twelve months. They are reference points, not a pass mark. A result below one does not mean you cannot conceive, and clearing all six does not guarantee you will. Our article on what a semen analysis measures goes through each parameter.
If you have a varicocele, concentration and motility are the parameters most likely to be affected. Total motile count, which combines volume, concentration and motility into one figure, is the most useful number to track over time because it captures changes the individual parameters can mask.
Testing options in the UK
Through the NHS. A GP can refer you for a semen analysis. Most services expect a couple to have been trying to conceive for twelve months first, and waiting times vary considerably between trusts. The analysis is thorough and free.
Private clinic. Faster access with no twelve-month requirement. You produce the sample on site or deliver it within a short window, and costs typically run into the low hundreds per analysis.
At home. You test in your own bathroom and get results without a referral or a waiting list. For a man who has just been told he has a varicocele and wants to know whether it matters, this removes the two things that stop most men testing at all: the wait and the room.
The ExSeed home sperm test measures concentration, motility and volume, and calculates total motile count. Because you keep the device, you can retest whenever you need rather than booking each time.
Why one test is not enough
Semen parameters vary substantially between samples from the same man. Illness, fever, abstinence period, sleep and stress all move the numbers. A single low result is not a diagnosis, which is why clinical practice uses more than one sample before drawing conclusions.
Two tests a few weeks apart give a far more reliable picture than one. If you are monitoring a varicocele over time, or checking whether a lifestyle change has done anything, repeat testing is the whole point rather than an upsell.
The 74-day rule
Sperm take roughly 74 days to develop, with further time for maturation and transit. Anything you change today shows up in a test around three months from now.
This applies to treatment as much as to lifestyle. A semen analysis six weeks after a procedure tells you very little. Long-term follow-up data published in Andrology tracked semen parameters at 6, 12, 18 and 24 months after varicocelectomy, which reflects how slowly this picture develops.
What UK guidance says about treatment
This is where UK practice diverges from much of what you will read online, so it is worth being precise.
NHS referral guidance advises against routinely referring the male partner of an infertile couple for varicocele surgery as a fertility treatment, on the grounds that it does not improve pregnancy rates.
The underlying evidence is the 2021 Cochrane review of surgical and radiological varicocele treatment in subfertile men, which pooled 48 randomised controlled trials covering 5,384 men. Its conclusion on live birth is that the effect remains uncertain. On pregnancy it is more positive: couples with no or delayed treatment had around a 21% chance of pregnancy, against 22% to 48% after treatment. Uncertain live birth evidence and a possible pregnancy benefit is a genuinely mixed picture, and UK commissioning has landed on the cautious reading.
International andrology bodies take a more favourable view in selected cases. A 2023 systematic review and meta-analysis in the World Journal of Men's Health compared men who had varicocele repair against untreated controls and found improvements in sperm concentration, total count, motility and morphology. Improved semen parameters and improved live birth rates are not the same endpoint, which is the heart of the disagreement.
Where treatment is offered in the UK, it is usually for persistent pain, or in selected fertility cases after specialist assessment. Guy's and St Thomas' describes embolisation, a non-surgical day case procedure that blocks the affected veins using coils or foam.
None of this is a decision to make from an article. What you can do is arrive at that appointment with actual numbers, which makes the conversation considerably more useful than arriving with a diagnosis and no data.
What to do next
If you have a varicocele and you are trying to conceive, or expect to within the next year or two, get a baseline semen analysis. A normal result removes a worry. A low result means you found it early and now have a figure to measure any change against.
Either way you stop guessing, which is where most men with this diagnosis are left.
Frequently asked questions
Does a varicocele always affect fertility?
No. Most men with a varicocele have normal semen parameters and conceive without difficulty. Population research links varicocele to reduced sperm quality on average, but it does not determine any individual result, which is why testing is the only way to know your own position.
Can I test for a varicocele at home?
No. A varicocele is diagnosed by physical examination or scrotal ultrasound, both of which need a clinician. What you can measure at home are the sperm parameters a varicocele may affect: concentration, motility and total motile count.
How long after varicocele surgery should I do a sperm test?
Sperm development takes around three months, so a test earlier than that will not reflect any change. Follow-up studies typically assess semen parameters from six months onwards, tracking to 24 months.
Will the NHS treat a varicocele to improve my fertility?
Not routinely. UK referral guidance advises against varicocele surgery as a fertility treatment for the male partner of an infertile couple, because the evidence does not demonstrate improved pregnancy rates. Treatment is more commonly considered for persistent pain, or in selected cases after specialist assessment.
Does a varicocele affect testosterone?
It can. Varicocele has been associated with altered reproductive hormone levels in large population studies. A semen analysis does not measure testosterone, so that needs a separate blood test. See our guide to low testosterone in men.
What sperm test result is considered normal?
The WHO sixth edition reference limits are 16 million per ml concentration, 42% total motility, 30% progressive motility, 4% normal morphology and 1.4 ml volume. These are population reference points rather than a pass or fail threshold.
