Can a Unilateral Varicocele Cause Atrophy in Both Testicles?
No, a unilateral varicocele typically causes atrophy only in the ipsilateral (same side) testis, not both testicles. However, there is evidence that the contralateral testis may also be affected in some cases, though this is less common and less severe.
Ipsilateral Testicular Atrophy
- Unilateral varicoceles, particularly left-sided ones, are strongly associated with ipsilateral testicular atrophy or hypotrophy. 1
- Men with left varicoceles demonstrate significantly greater testicular volume differences (mean 3.1 ± 0.4 ml) compared to men without varicoceles (mean 1.6 ± 0.3 ml), confirming that varicoceles cause significant ipsilateral testicular atrophy. 1
- For adolescents, the European Association of Urology strongly recommends surgery for varicocele associated with a persistent small testis (size difference of >2 ml or 20%), which should be confirmed on two subsequent visits performed 6 months apart. 2
- After microsurgical varicocelectomy in adolescents with unilateral varicocele, the treated testis grew an average of 50.1%, while the contralateral testis grew only 23%, demonstrating that the atrophy is predominantly ipsilateral. 3
Contralateral Testicular Effects
- While the primary atrophic effect is ipsilateral, there is evidence of contralateral testicular dysfunction. Patients with testicular germ cell tumors have Leydig cell dysfunction even in the contralateral testis, suggesting systemic effects can occur. 2
- The pathophysiology of varicocele involves higher scrotal temperature, hypoxia, and reflux of toxic metabolites that can cause testicular dysfunction through increased DNA damage—mechanisms that could theoretically affect both testicles. 2, 4
- However, the clinical evidence shows that testicular volume discrepancy in varicocele patients reflects primarily ipsilateral atrophy rather than bilateral atrophy. 1
Clinical Implications
- When evaluating a patient with unilateral varicocele, measure testicular volumes bilaterally using an orchidometer or ultrasound. 5
- A size difference of >2 ml or 20% between testicles in adolescents warrants consideration for surgical intervention. 2
- If bilateral testicular atrophy is present in a patient with unilateral varicocele, investigate other causes of testicular dysfunction such as hypogonadism, genetic abnormalities (karyotype and Y-chromosome microdeletion analysis for sperm counts <5 million/ml), or other systemic conditions. 4
- The presence of bilateral atrophy should not be automatically attributed to a unilateral varicocele alone. 1
Important Caveats
- Approximately 80% of men with varicoceles remain fertile, and testicular volume difference alone does not predict infertility status. 1
- Treatment should focus on men with clinical (palpable) varicoceles and either abnormal semen parameters or documented testicular atrophy, not on subclinical varicoceles. 2, 6
- Do not treat varicocele in infertile men who have normal semen analysis or in men with a subclinical varicocele. 2