Is a testicle length of 3.8 cm considered normal in an adult male?

Testicular Size Assessment: 3.8 cm Length

A testicular length of 3.8 cm falls within the normal range for adult males and corresponds to a testicular volume of approximately 15-18 ml, which is above the 12 ml threshold that defines testicular atrophy. 1

Understanding Normal Testicular Dimensions

• The American Urological Association suggests that a testicular volume of 12 ml is generally considered the lower limit of normal, with a 4 cm testicular length corresponding to a volume of approximately 15-18 ml 1
• A testicular length of 3.8 cm, when combined with typical width and height measurements, yields a volume that exceeds the 12 ml atrophy threshold 1
• The European Association of Urology recommends that testicular volumes below 12 ml are associated with impaired spermatogenesis, higher risk of intratubular germ cell neoplasia, and potential infertility 1

Clinical Significance of Testicular Volume

• Testicular volume strongly correlates with total sperm count and sperm concentration, with volumes of 15-18 ml associated with normal spermatogenesis and adequate fertility potential 1
• Mean testicular size has the strongest correlation with serum follicle-stimulating hormone levels, total sperm count and sperm concentration 2
• Testicular volumes less than 12 ml are definitively considered atrophic and associated with significant pathology 1

Important Clinical Caveats

• If there is a size discrepancy between testes greater than 2 ml or 20%, further evaluation including ultrasound may be warranted to exclude pathology 1
• The American Academy of Family Physicians recommends that in the context of infertility, even "normal-sized" testes should prompt semen analysis, as testicular volume alone cannot definitively predict fertility status 1
• Physical examination using a Prader orchidometer provides a good surrogate for volume measured via ultrasound in most cases 1

When Additional Evaluation Is Needed

• Testicular atrophy (volume <12 ml) in combination with a history of cryptorchidism warrants testicular biopsy to screen for intratubular germ cell neoplasia 1
• Men with testicular volume <12 ml have a >34% risk of intratubular germ cell neoplasia in the contralateral testis if testicular cancer is present, especially in those under 30 years of age 1
• Scrotal ultrasound is indicated in selected cases where physical examination is difficult, such as with large hydrocele, inguinal testis, or epididymal enlargement 1

Measurement Considerations

• External measurements with calipers typically overestimate testicular dimensions by 5.7 mm in length, 2.9 mm in thickness, and 1.4 mm in width compared to ultrasound 3
• The Lambert formula (Length × Width × Height × 0.71) provides the most accurate estimates of testicular volume compared to actual measurements 1
• High-frequency probes (>10 MHz) should be used to maximize resolution and accurate caliper placement for ultrasound testicular volume measurement 1