Varicocele and Male Infertility: Can It Cause Low Sperm Count?

Varicocele is one of the most frequently diagnosed — and most treatable — causes of male infertility. Despite being common, many men have never heard of it until a fertility evaluation uncovers it. Understanding what varicocele is and how it affects fertility can help you decide whether treatment is worth considering.

What Is a Varicocele?

A varicocele is an enlargement of the veins within the scrotum, similar to varicose veins that can occur in the legs. These veins are part of the network that drains blood away from the testicle; when the valves inside them don’t work properly, blood pools and the veins swell.

• Found in a significant proportion of the general male population
• More common on the left side, due to the anatomy of the veins involved
• Found in a notably higher proportion of men being evaluated for infertility

How Varicocele Affects Fertility

The exact mechanism isn’t fully understood, but the leading theory involves heat and blood flow:

• Pooled blood raises the temperature inside the scrotum
• Sperm production is highly temperature-sensitive and requires a slightly cooler environment than body temperature
• The elevated temperature and altered blood flow can reduce sperm count, motility, and normal shape (morphology) over time
• Some studies also link varicocele to increased oxidative stress on sperm, which can affect sperm DNA quality

Not every man with a varicocele has fertility problems — many father children without any issue. But when a couple is struggling to conceive and a varicocele is found, it’s a common and often correctable contributing factor.

Symptoms of Varicocele

Many varicoceles cause no symptoms at all and are only found during a fertility work-up or routine exam. When symptoms do occur, they may include:

• A dull ache or heaviness in the scrotum, often worse after standing, exercise, or by the end of the day
• A visible or palpable “bag of worms” feeling above the testicle
• Noticeable shrinkage of the affected testicle over time, in more significant cases

How Varicocele Is Diagnosed

• Physical examination — often felt by the doctor, especially when standing and during a Valsalva manoeuvre (bearing down)
• Scrotal ultrasound with Doppler — confirms the diagnosis and grades its severity
• Semen analysis — assesses whether sperm count, motility, or morphology have been affected

Treatment: Does Varicocele Repair Improve Fertility?

Not every varicocele needs treatment. Repair is generally considered when:

• The varicocele is clinically significant (palpable, not just seen on ultrasound)
• Semen parameters are abnormal
• The couple is experiencing otherwise unexplained infertility, and no other major cause is found

Treatment options include:

• Microsurgical varicocelectomy — a precise surgical technique to tie off the affected veins while preserving healthy structures, generally considered the most effective and lowest-complication approach
• Laparoscopic repair — a minimally invasive alternative
• Embolization — a non-surgical, radiologically guided procedure to block the affected veins

Improvement in semen parameters is typically assessed 3–6 months after repair, since sperm takes around 70–90 days to develop. Many men see a meaningful improvement in sperm count and motility, which can improve natural conception chances or the success of assisted reproduction if it’s still needed.

Varicocele repair does not guarantee pregnancy, but it is one of the few surgically correctable causes of male infertility — which makes proper evaluation worthwhile.

FAQs

Conclusion

Varicocele is common, often silent, and one of the few directly correctable causes of male infertility. If you’ve been diagnosed with a varicocele — or are struggling to conceive and haven’t yet been evaluated — a scrotal ultrasound and semen analysis can clarify whether it’s contributing, and whether repair is likely to help.