Can Unilateral Varicocele Cause Bilateral Testicular Atrophy?
Yes, a unilateral (typically left-sided) varicocele can cause testicular atrophy on both sides, though the mechanism differs between the affected and contralateral testis.
Mechanism of Bilateral Testicular Dysfunction
The pathophysiology involves multiple systemic effects that impact both testicles, even when the varicocele appears clinically unilateral:
Higher scrotal temperature, testicular hypoxia, and reflux of toxic metabolites cause testicular dysfunction through increased DNA damage and oxidative stress affecting the entire scrotal environment 1
Right varicocele is frequently present but undetectable by physical examination - venographic studies of 840 infertile men with varicocele found right varicocele in the vast majority of patients, despite being clinically diagnosed as left-sided only 2
Pathologic hydrostatic pressure from destroyed one-way valves produces pressure in the testicular venous system approximately five times higher than normal, exceeding arteriolar pressure and reversing the pressure gradient between arterioles and venules, leading to persistent hypoxia bilaterally 2
Clinical Evidence of Bilateral Atrophy
Both testicles of subfertile men with varicoceles were significantly smaller than testicles of subfertile men without varicoceles, demonstrating bilateral impact even from clinically unilateral disease 3
In a study of 82 healthy volunteers and 88 subfertile men, those with varicoceles showed bilateral testicular size reduction compared to controls without varicoceles 3
Treatment Response Confirms Bilateral Impact
After unilateral varicocelectomy, the treated testis grew an average of 50.1% while the contralateral testis grew only 23%, suggesting the contralateral side was also affected but to a lesser degree 4
89% of patients with testicular atrophy demonstrated reversal of testicular growth retardation after unilateral varicocelectomy, with catch-up growth occurring in both testicles 4
After bilateral varicocelectomy, both testes showed similar growth rates (45% left testis, 39% right testis), confirming that both sides benefit from treatment 4
Critical Clinical Implications
The European Association of Urology strongly recommends surgery for varicocele when associated with persistent testicular size difference >2 mL or 20%, confirmed on two visits 6 months apart 1
Treatment should target clinical (palpable) varicoceles with abnormal semen parameters or documented testicular atrophy 1
Only bilateral occlusion of the internal spermatic veins, including associated bypasses, eliminates the pathologic hydrostatic pressure and allows resumption of arterial blood flow in the testicular microcirculation 2
Important Caveats
Treatment of subclinical (non-palpable) varicoceles detected only by ultrasound is not effective and should not be pursued 1, 5
Improvements in testicular volume typically occur within 3-6 months (two spermatogenic cycles) after surgery, so patience is required when assessing treatment response 1
The varicocele-induced damage is potentially reversible, as varicocelectomy can reverse sperm DNA damage and improve oxidative stress levels 1