A varicocele is found in about 15 percent of all healthy men, and in up to around 35 percent of men presenting with primary fertility problems (PMID 26763551). That is an enormous gap between two groups.
That gap is exactly what makes it the most-discussed correctable cause of reduced fertility in men.
And it is exactly where the exaggeration starts. Because most men with a varicocele go on to have children, and what treatment actually delivers is far less certain than almost every website claims.
What is a varicocele?
A bundle of widened veins above your testicle, much like varicose veins in your leg. The valves in those veins no longer close properly, so blood flows back and pools. That makes the area warmer, and heat is precisely what your sperm production tolerates badly.
That temperature route is the most commonly cited explanation, though it is not the only one.
Researchers also point to oxygen shortage in the tissue and backflow of substances from the renal vein. Honestly, the mechanism is not fully settled.
What is clear: many men with a varicocele never notice a thing and have children without difficulty (PMID 28865534).
What are the symptoms of a varicocele?
Usually none. When there are symptoms, it is a heavy or nagging feeling in your scrotum that builds through the day, gets worse standing or exercising, and eases once you lie down. Some men feel a bundle above the testicle, often described as a bag of worms.
That pattern, worse standing and better lying down, is fairly characteristic.
A large varicocele may be visible when you stand and disappear when you lie down. A small one you will not notice at all, and it is often found by chance.
Sharp, sudden pain does not belong here. That is a different story, covered in testicle pain.
Why is a varicocele almost always on the left?
Because of the plumbing. The vein from your left testicle joins your left renal vein at a right angle, while on the right it runs at a slant into the large vena cava. That angle creates more back pressure on the left, so problems build up there faster.
It is one of those cases where engineering explains more than biology.
A varicocele on the right side only is unusual. Doctors will generally look a bit further in that case, because sometimes something else in the abdomen is involved.
That is no reason to panic, but it is a reason to have it assessed by a doctor rather than by a search engine.
What does a varicocele do to your fertility?
It may put your sperm quality under pressure, but it does not have to. Men with a varicocele more often show a lower sperm concentration, less motility and more abnormally shaped cells. At the same time, most men with a varicocele have no fertility problem at all.
Those two sentences sit side by side, and both are true.
So it is a risk factor, not a diagnosis. That distinction goes missing online constantly.
Because production in the testicle itself may come under pressure, your hormones can move with it. A rising FSH and a falling inhibin B fit a sperm production that is not running well. How those two connect is explained in testicles: how they work.
What treatment is there for a varicocele?
A urologist can close off the affected veins, either surgically or via a catheter. In microsurgery, the veins are tied off under a microscope. In embolisation, a radiologist threads a small coil or fluid through a blood vessel to the spot and seals the vein from the inside. Whether treating makes sense depends on your symptoms, your semen analysis and whether you want children.
That last sentence is not hedging. It is exactly what the debate is about.
A varicocele with no symptoms and a perfectly good semen analysis is generally not treated. There is nothing to gain.
What treatment means for your situation is decided by the urologist together with you. We cannot do that, and neither can a blood test.
Does treating a varicocele help you conceive?
Maybe, and the evidence is weaker than most websites suggest. The 2021 Cochrane review looked at 48 studies with 5,384 men and concludes that treatment may improve the chance of pregnancy, but that it remains uncertain whether it also leads to more live births (PMID 33890288).
That distinction between a pregnancy and a baby being born is not pedantry. It is the only thing you ultimately care about.
Below is what that review actually found per outcome, including how certain the authors themselves are.
| Outcome | What Cochrane finds | How certain is the evidence |
|---|---|---|
| Chance of pregnancy | Possibly higher after treatment, roughly 22 to 48 percent against 21 percent without | Low certainty |
| Live births | Uncertain whether treatment helps | Very low certainty |
| Microsurgery versus other techniques | Probably slightly better pregnancy odds and less recurrence | Moderate certainty |
Read that second row again. On the outcome that matters most, the authors honestly say they do not know.
That is not a reason to write treatment off. It is a reason to let nobody promise you anything.
Which blood values relate to a varicocele?
Blood tests do not diagnose a varicocele. A doctor does that with their hands and an ultrasound. Where blood values do add something is the question of what it means for your production. FSH, inhibin B, LH and testosterone together tell you whether the factory is still running.
So the diagnosis comes from the urologist, and the context from your blood.
Some men choose to get that hormonal side in view alongside their semen analysis, for instance with the IVF partner screening or the Hormones Man panel. Always discuss an unusual result with your GP.
Which other causes play a part when it is not happening is set out in male infertility. How to read a semen analysis is in semen analysis values, and the complete story starts with male fertility.
If you feel a heavy, nagging sensation that worsens when you stand, just book an appointment. The examination takes five minutes and is a lot less uncomfortable than months of googling.
References
- Persad E, et al. Surgical or radiological treatment for varicoceles in subfertile men. Cochrane Database of Systematic Reviews. 2021. PMID 33890288.
- Alsaikhan B, et al. Epidemiology of varicocele. Asian Journal of Andrology. 2016. PMID 26763551.
- Clavijo RI, et al. Varicoceles: prevalence and pathogenesis in adult men. Fertility and Sterility. 2017. PMID 28865534.
- Thuisarts. Pain in your scrotum. thuisarts.nl
Every blood test result at Caliber includes a professional assessment by a BIG-registered doctor. For treatment decisions, always discuss your results with your GP.
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