Can a varicocele cause infertility in men?

Can Varicocele Cause Infertility?

Yes, varicocele is a well-established cause of male infertility and represents the most common correctable cause of male factor infertility, present in 35-40% of men presenting with infertility compared to only 15% of the general male population. 1

Epidemiological Evidence of Causation

The association between varicocele and infertility follows a clear dose-response relationship that strongly suggests causation:

• 15% prevalence in normal fertile men 1
• 25% prevalence in men with abnormal semen analysis 1
• 35-40% prevalence in men presenting with primary infertility 1
• Up to 80% prevalence in men with secondary infertility 2

This progressive increase in prevalence across populations with worsening fertility demonstrates that varicocele is not merely an incidental finding but a pathological contributor to infertility. 3

Mechanisms of Fertility Impairment

Varicoceles damage testicular function through multiple pathophysiological mechanisms:

• Elevated scrotal temperature from venous stasis impairs spermatogenesis 1
• Testicular hypoxia from impaired venous drainage causes cellular dysfunction 1
• Reflux of toxic metabolites from renal and adrenal veins damages testicular tissue 1
• Increased oxidative stress leads to sperm DNA damage, which is now recognized as a sensitive biomarker of varicocele-induced injury 3

A critical caveat: varicocele appears to be a progressive lesion, meaning that even men with currently normal semen parameters or documented prior fertility remain at risk for subsequent testicular dysfunction and infertility if left untreated. 4

Evidence That Treatment Reverses Infertility

The strongest proof that varicoceles cause infertility comes from treatment outcomes:

• Varicocele repair improves semen parameters in men with clinical varicoceles and abnormal semen analysis 1
• Spontaneous pregnancy rates increase following varicocelectomy, typically occurring 6-12 months post-surgery 1
• Improvements require 3-6 months (two spermatogenic cycles) to manifest, consistent with the timeline of spermatogenesis 1, 2
• Assisted reproductive technology outcomes improve following varicocele repair in oligozoospermic men (OR 1.69) 1
• Even men with non-obstructive azoospermia may have sperm return to the ejaculate after varicocelectomy, particularly those with hypospermatogenesis 5

Clinical Decision-Making Algorithm

Who should be treated:

• Men with palpable (clinical) varicoceles AND abnormal semen parameters 1, 5
• Men with non-obstructive azoospermia and clinical varicocele, especially with hypospermatogenesis on biopsy, after thorough counseling 5
• Adolescents with persistent testicular size difference >2 mL or 20% confirmed on two visits 6 months apart 5

Who should NOT be treated:

• Men with normal semen analysis, regardless of varicocele size 1
• Men with subclinical (non-palpable) varicoceles detected only by ultrasound 1, 6
• Men with complete AZFa or AZFb deletions on Y-chromosome microdeletion testing 5

Critical pitfall to avoid: Do not routinely use ultrasonography to identify non-palpable varicoceles, as treatment of subclinical varicoceles does not improve semen parameters or fertility rates. 1, 5

Special Considerations

For couples with female partner limitations:

• If the female partner has limited ovarian reserve, consider proceeding directly to sperm retrieval rather than waiting 6-12 months for potential sperm return after varicocelectomy 5, 6

For severe oligozoospermia (<5 million/mL):

• Obtain karyotype and Y-chromosome microdeletion analysis before varicocelectomy, as chromosomal abnormalities occur in 4% of these men (tenfold higher than general population) 5

Grade 3 (large) varicoceles:

• Show greater improvement in sperm count after surgical repair compared to moderate or mild varicoceles 1
• Are associated with worse baseline semen parameters and greater testicular dysfunction 5