Is having testicles of different sizes, 20ml and 16ml, a concern?

Testicular Size Difference Between 20ml and 16ml

Having testicles of different sizes (20ml and 16ml) is not a medical concern, as this difference falls within normal variation and does not meet clinical criteria for significant testicular asymmetry.

Normal Testicular Size and Variation

• Normal adult testicular volume typically ranges from 15-25ml, with the average being around 17-19ml 1
• A size difference of 4ml (20ml vs 16ml) represents approximately 20% difference, which is at the borderline of what might be considered clinically significant 2
• Both testicles in this case fall within the normal size range for adult males 3, 1

Clinical Significance of Testicular Size Differences

• According to European Association of Urology guidelines, a persistent testicular size difference of >2ml or 20% is considered potentially significant, but primarily in adolescents with varicocele 2
• Testicular volumes less than 12ml are considered small or atrophic and may warrant further investigation, but both testicles in this case exceed this threshold 3
• Significant testicular asymmetry may indicate underlying conditions such as varicocele, history of cryptorchidism, or testicular atrophy, but the current difference is borderline 2

When to Be Concerned About Testicular Size

• Testicular volumes below 12ml are associated with higher risk of intratubular germ cell neoplasia and impaired spermatogenesis 3
• Total testicular volume (sum of both testes) below 30ml by orchidometer or 20ml by ultrasound correlates with subnormal sperm counts 4
• In this case, the total testicular volume is 36ml, which exceeds these thresholds 4

Monitoring Recommendations

• Regular testicular self-examination is recommended regardless of testicular size to detect any changes that might indicate testicular cancer 2
• If there are additional risk factors such as infertility concerns, history of undescended testicles, or testicular pain, further evaluation may be warranted 3
• If the size difference increases over time or if either testicle becomes smaller than 12ml, medical evaluation would be recommended 3

Common Causes of Testicular Size Differences

• Minor asymmetry between testicles is common and often physiological 5
• Significant asymmetry may be related to:
  • Previous trauma or inflammation 6
  • History of cryptorchidism (undescended testicle) 6
  • Varicocele (enlarged veins in scrotum) 2
  • Testicular atrophy from various causes 6

When Further Evaluation Is Needed

• If either testicle is <12ml (atrophic) 3
• If there is a history of undescended testicles, testicular pain, or trauma 2
• If there are fertility concerns or abnormal hormone levels 2
• If the size difference is accompanied by a palpable mass or other abnormalities 2

In conclusion, a testicular size of 20ml and 16ml represents a mild asymmetry that falls within normal variation and does not require medical intervention in the absence of other symptoms or risk factors.