Varicocele, the Most Common Fixable Cause of Male Infertility

What a Varicocele Actually Is

A varicocele is an enlargement of the veins that drain blood from the testicle, similar in nature to a varicose vein in the leg — the valves inside the vein that normally keep blood flowing in one direction don't work properly, so blood pools and the vein widens. It typically develops during puberty and is more often found on the left side than the right, largely because of how the left testicular vein connects into the larger venous system compared to the right.

varicocele — an enlargement of the veins draining the testicle, similar to a varicose vein, that can sometimes be seen or felt as a soft, twisting mass above the testicle, often described as feeling like a "bag of worms"

Many varicoceles cause no symptoms at all and are found incidentally during a physical exam for something unrelated, including a fertility evaluation.

How a Varicocele Can Affect Fertility

The leading explanation for why a varicocele affects fertility centers on temperature and blood flow: the pooled blood in an enlarged vein is thought to raise the temperature around the testicle slightly above what's ideal for sperm production, and to alter local blood flow and oxygen delivery in ways that can impair how sperm develop. In men whose fertility is affected, this typically shows up as lower-than-expected results on a semen analysis — reduced concentration, reduced motility, or an increased proportion of abnormally shaped sperm, measured against standard reference values 1Ref 1World Health Organization (2021).WHO laboratory manual for the examination and processing of human semen, 6th edition.The reference standard for how a semen analysis is performed and interpreted, including concentration, motility, and morphology, against which varicocele-related changes are measured..

having a varicocele does not mean fertility is definitely affected — many men with one have semen analyses and fertility entirely within the normal range

How a Varicocele Is Diagnosed

A varicocele is usually first identified on a physical exam, with the patient standing and sometimes bearing down slightly, which makes the enlarged veins easier to feel or see. When the physical exam is unclear, or when more detail is needed to plan treatment, a scrotal ultrasound can confirm the finding and measure the size of the affected veins more precisely.

Because a varicocele evaluation is one part of a broader male-factor workup, it's typically found alongside a semen analysis and history rather than checked for on its own — joint urology and reproductive-medicine guidance calls for evaluating the male partner with history, exam, and semen analysis together, concurrent with the female partner's evaluation 2Ref 2American Urological Association / American Society for Reproductive Medicine (2020).Diagnosis and treatment of infertility in men: AUA/ASRM guideline part I.Guidance calling for concurrent evaluation of the male partner with history, physical exam, and semen analysis alongside the female partner's evaluation..

Not Every Varicocele Needs to Be Fixed

The presence of a varicocele on its own is not an automatic reason for surgery. Current guidance frames varicocele repair as one of several medical and surgical therapies available for male-factor infertility, generally considered when a varicocele is found alongside abnormal semen parameters and no other cause has been identified that would better explain the difficulty conceiving 3Ref 3American Urological Association / American Society for Reproductive Medicine (2020).Diagnosis and treatment of infertility in men: AUA/ASRM guideline part II.Varicocele repair is one of the medical and surgical therapy options for male-factor infertility, considered when abnormal semen parameters accompany the finding..

A varicocele found on exam with a completely normal semen analysis, in someone without a fertility concern, often doesn't need any treatment at all — it's monitored rather than repaired. The decision to treat is driven by the combination of findings, not the varicocele in isolation.

What Varicocele Repair Actually Involves

Varicocele repair, sometimes called varicocelectomy, redirects blood flow away from the affected veins, either through a surgical procedure that ties off the problematic veins or through a radiology-guided procedure that blocks them from the inside using a catheter. Both approaches aim at the same outcome: stopping blood from pooling in the enlarged veins so testicular temperature and blood flow can return closer to normal 3Ref 3American Urological Association / American Society for Reproductive Medicine (2020).Diagnosis and treatment of infertility in men: AUA/ASRM guideline part II.Varicocele repair is one of the medical and surgical therapy options for male-factor infertility, considered when abnormal semen parameters accompany the finding..

Repair is one of the few male-factor interventions with real evidence behind it as an option that can meaningfully improve semen parameters, which is part of why it's often the first thing addressed when a varicocele is found together with abnormal semen findings, rather than moving straight to a treatment like IUI or IVF that works around the sperm quality rather than trying to improve it.

Recovery from the surgical approach typically involves a short period of limited physical activity, and any improvement in semen parameters doesn't show up immediately — sperm production takes time, so a repeat semen analysis is usually not scheduled until a few months after the procedure, which can make the waiting period feel long for a couple already anxious about time. The radiology-guided approach generally has a shorter physical recovery, though the timeline for seeing any change in semen parameters is similar either way, since it's driven by how long sperm take to develop rather than by which procedure was used.

What Else Is Worth Checking at the Same Visit

Heat exposure is worth discussing at the same visit, since it plausibly compounds whatever temperature effect a varicocele is already having — prolonged exposure to hot tubs, saunas, or other sustained heat sources is one of several everyday habits that lower sperm count that's reasonable to address regardless of whether varicocele repair is also planned. Tobacco and marijuana use are separately associated with reduced fertility-treatment success and worse outcomes, independent of any varicocele finding, which makes them a genuinely evidence-backed place to focus effort in the meantime 4Ref 4Practice Committee of ASRM (2024).Tobacco or marijuana use and infertility: a committee opinion.Tobacco and marijuana use are associated with reduced fertility-treatment success, independent of any varicocele finding..

None of these lifestyle factors are a substitute for repair when repair is actually indicated — they're additive steps, not alternatives to it.

Timing and Getting the Full Picture

Because a varicocele is only one possible finding in a broader evaluation, it's worth pursuing a male fertility workup in full rather than stopping at the varicocele diagnosis alone — a full evaluation also considers hormone levels and overall reproductive history. The standard guidance is to begin a fertility evaluation after twelve months of trying for a couple where the woman is under 35, or six months if she's 35 or older, since female age remains the single strongest predictor of how quickly to move from evaluation to treatment 5Ref 5Practice Committee of ASRM and the Society for Reproductive Endocrinology and Infertility (2022).Optimizing natural fertility: a committee opinion.Female age is the single most important predictor of fecundity, and evaluation is recommended at 12 months of trying if under 35, or 6 months if 35 or older..

For couples navigating a varicocele diagnosis alongside other fertility questions, patient-advocacy organizations maintain resources on treatment options, coverage, and connecting with others in a similar situation 6Ref 6RESOLVE: The National Infertility Association (2024).RESOLVE: The National Infertility Association — Insurance Coverage and Support Resources.The existence of patient-advocacy resources on treatment options, coverage, and connecting with others navigating a male-factor fertility diagnosis..